The Hydrogen Bridge

Interactions without borders

Gautam R DesirajuSchool of Chemistry

University of HyderabadHyderabad 500 046 India

Pisa 6 September 2005

Under certain conditions an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond between them

Hydrogen bond XndashHhellipAPauling definition (1939)

A hydrogen bond is said to exist when (1) there is evidence of a bond and (2) there is evidencethat this bond sterically involves a hydrogen atomalready bonded to another atom

Hydrogen bond XndashHhellipAPimentelndashMcClellan definition (1960)

Hydrogen bond XndashHhellipASteinerndashSaenger definition (1993)

Any cohesive interaction where H carries a positive charge and A a negative charge (partial or full) and the charge on H is more positive than on X

Hydrogen bond

OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO

OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO

OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ

How to assess hydrogen bonds

bull Energybull Spectroscopybull Geometrybull Structurebull Function

A complex interaction

lt 001001 to 005005 to 02∆(XndashH) Aring

VariableDistinctivePronouncedEffect on crystal packing

30-80~100100Shorter than van der Waals

20 to 3015 to 2212 to15HhellipA Aring

lt55-25gt25IR νs

lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)

CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash

WeakStrongVery strong

The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low

electronegativity (1999)

DesirajundashSteiner definition

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Under certain conditions an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond between them

Hydrogen bond XndashHhellipAPauling definition (1939)

A hydrogen bond is said to exist when (1) there is evidence of a bond and (2) there is evidencethat this bond sterically involves a hydrogen atomalready bonded to another atom

Hydrogen bond XndashHhellipAPimentelndashMcClellan definition (1960)

Hydrogen bond XndashHhellipASteinerndashSaenger definition (1993)

Any cohesive interaction where H carries a positive charge and A a negative charge (partial or full) and the charge on H is more positive than on X

Hydrogen bond

OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO

OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO

OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ

How to assess hydrogen bonds

bull Energybull Spectroscopybull Geometrybull Structurebull Function

A complex interaction

lt 001001 to 005005 to 02∆(XndashH) Aring

VariableDistinctivePronouncedEffect on crystal packing

30-80~100100Shorter than van der Waals

20 to 3015 to 2212 to15HhellipA Aring

lt55-25gt25IR νs

lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)

CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash

WeakStrongVery strong

The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low

electronegativity (1999)

DesirajundashSteiner definition

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

A hydrogen bond is said to exist when (1) there is evidence of a bond and (2) there is evidencethat this bond sterically involves a hydrogen atomalready bonded to another atom

Hydrogen bond XndashHhellipAPimentelndashMcClellan definition (1960)

Hydrogen bond XndashHhellipASteinerndashSaenger definition (1993)

Any cohesive interaction where H carries a positive charge and A a negative charge (partial or full) and the charge on H is more positive than on X

Hydrogen bond

OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO

OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO

OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ

How to assess hydrogen bonds

bull Energybull Spectroscopybull Geometrybull Structurebull Function

A complex interaction

lt 001001 to 005005 to 02∆(XndashH) Aring

VariableDistinctivePronouncedEffect on crystal packing

30-80~100100Shorter than van der Waals

20 to 3015 to 2212 to15HhellipA Aring

lt55-25gt25IR νs

lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)

CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash

WeakStrongVery strong

The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low

electronegativity (1999)

DesirajundashSteiner definition

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Hydrogen bond XndashHhellipASteinerndashSaenger definition (1993)

Any cohesive interaction where H carries a positive charge and A a negative charge (partial or full) and the charge on H is more positive than on X

Hydrogen bond

OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO

OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO

OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ

How to assess hydrogen bonds

bull Energybull Spectroscopybull Geometrybull Structurebull Function

A complex interaction

lt 001001 to 005005 to 02∆(XndashH) Aring

VariableDistinctivePronouncedEffect on crystal packing

30-80~100100Shorter than van der Waals

20 to 3015 to 2212 to15HhellipA Aring

lt55-25gt25IR νs

lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)

CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash

WeakStrongVery strong

The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low

electronegativity (1999)

DesirajundashSteiner definition

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Hydrogen bond

OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO

OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO

OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ

How to assess hydrogen bonds

bull Energybull Spectroscopybull Geometrybull Structurebull Function

A complex interaction

lt 001001 to 005005 to 02∆(XndashH) Aring

VariableDistinctivePronouncedEffect on crystal packing

30-80~100100Shorter than van der Waals

20 to 3015 to 2212 to15HhellipA Aring

lt55-25gt25IR νs

lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)

CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash

WeakStrongVery strong

The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low

electronegativity (1999)

DesirajundashSteiner definition

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

How to assess hydrogen bonds

bull Energybull Spectroscopybull Geometrybull Structurebull Function

A complex interaction

lt 001001 to 005005 to 02∆(XndashH) Aring

VariableDistinctivePronouncedEffect on crystal packing

30-80~100100Shorter than van der Waals

20 to 3015 to 2212 to15HhellipA Aring

lt55-25gt25IR νs

lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)

CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash

WeakStrongVery strong

The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low

electronegativity (1999)

DesirajundashSteiner definition

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

lt 001001 to 005005 to 02∆(XndashH) Aring

VariableDistinctivePronouncedEffect on crystal packing

30-80~100100Shorter than van der Waals

20 to 3015 to 2212 to15HhellipA Aring

lt55-25gt25IR νs

lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)

CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash

WeakStrongVery strong

The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low

electronegativity (1999)

DesirajundashSteiner definition

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low

electronegativity (1999)

DesirajundashSteiner definition

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Cl3ndashnRnCndashHhellipO

G R Desiraju J Chem Soc Chem Comm 179 1989

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Angles XndashHhellipO

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

IR bathochromic shifts CndashHhellipO

G R Desiraju and B N Murty Chem Phys Lett 139 360 1987

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Thermal parameters

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Isostructurality

N

N

H

O

O

O

EtEt N

NO

HH

HH

H231

205

N

N

H

O

O

O

EtEt

NO

HH

HH HH

256

201

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Two molecules in the asymmetric unit (Zrsquo=2)

OO

HH

HH H

Me2NO

O

H

CH3

H

Me2N

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Fluorine

CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor

Electronegativity and Hardness

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

F FF

F

F F

F

F

FF

FF

F

F

F

F

FF

FF

F

CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes

Thalladi Weiszlig et al JACS 120 8702 1998

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds

All C H F compounds Fluorobenzenes

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst

Zr+ H

H

FFF

Stereoselective polymerisationChan et al

Angew Chem Int Ed42 1628 2003

Boron adductsLancaster et al Chem Comm

2148 2003

Decrease of β-H transferT Fujita et al

JACS 124 3327 2002JACS 125 4293 2003

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition

Binding in thrombin

Diederich et al

Angew Chem Int Ed

42 2507 2003

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Electrostatics

Charge transfer (covalency)

Dispersionrepulsion (van der Waals)

Polarisation

A composite interaction

Hydrogen bridge (Wasserstoffbruumlcke)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

[HF2]-

Electrostatic limit(15 kcalmol)

van der Waals limit(025 kcalmol)

weak hydrogen bonds

Covalent limit (40 kcalmol)

very strong hydrogen bonds

strong hydrogen bonds

very weakinteractions

X H X

PhsdotsdotsdotPh

NH2

NH2

O O PO(OH)2H

NHsdotsdotsdotπNHsdotsdotsdotCo

R R

OOH

OCl5

N CH3H

NHsdotsdotsdotNH

OsHsdotsdotsdotOequivC

OHsdotsdotsdotOHCequivCHsdotsdotsdotOH

CHsdotsdotsdotClminusNHsdotsdotsdotS

Cl3CHsdotsdotsdotO=CMe2

CHsdotsdotsdotClCC=CHsdotsdotsdotO

OHsdotsdotsdotπ

CHsdotsdotsdotFCCHsdotsdotsdotS

CequivCHsdotsdotsdotπ

NH4+sdotsdotsdotFminus

NH4+RCOOminus

NH4+sdotsdotsdotClminus

NMe4+sdotsdotsdotXminus

CH4sdotsdotsdotπ

CH4sdotsdotsdotAr

OHsdotsdotsdotO=C

NH4+sdotsdotsdotπ

(NO2)3CHsdotsdotsdotO

NHsdotsdotsdotO=C

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Hydrogen bond (bridge)

DmdashHhelliphellipAA complex interaction that involves several atoms

A composite interaction that spans wide ranges of geometry and energy

Great chemical variations among the donor DmdashH and acceptor A groups

However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Hydrogen bridgeThe master-key of molecular recognition

StrengthDirectionalityWeaknessFlexibility

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ

Klaholz and Moras Structure 10 1197-1204 2002

Specificity

Reversibility

Affinity

Hydrophobicity

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Paulingrsquos definition

Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem

Modern definition

Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them

Bonds and bridges

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)

Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)