f.6 chemistry project dipole-dipole interaction and its application
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F.6 Chemistry ProjectDipole-dipole interaction and
its application
Fung Chun Yu (8)Kwok Chun Nga (9)Chan Wai Sum (5)
Introduction
• What is dipole-dipole interaction?– The difference in electronegativities between
elements in a covalent bond produces a certain degree of polarization
– The electron cloud is distorted, and a dipole is produced
Introduction
• What is dipole-dipole interaction?– example can be seen in hydrogen chloride (HCl)
– Cl, being more electronegative, pulls the electron cloud towards it Distortion of electron cloud
– The positive end attracts the negative end the molecules are packed regularly in a head-to-
tail fashion
Introduction
An illustration of the head-to-tail arrangement of molecules due to dipole-dipole interaction
Introduction
An extraordinarily simple animation showing the interaction between HCl molecules
Application of dipole-dipole interaction
–LCD
–Biological field
Liquid Crystal Display
• consists of two sheets of polarizing material with a liquid crystal solution in between• can be orientated into a a desired direction under current. • light will be polarized by this pattern
Why can the liquid crystal be arranged by electricity?
Liquid Crystal Display
• liquid crystal molecule used is introduced below• Methoxybenzilidene Butylanaline (MBBA)
• p-decyloxybenzylidene p'- amino 2-methylbutylcinnamate (DOBAMBC)
Liquid Crystal Display
• The molecules are dipoles • they twist the plane of polarization originally• They are aligned regularly
in a head-to-tail fashion asmentioned above when electric field is applied
formed a polaroid• light is then blocked
Biological Field• Molecular arrangement of
protein There are four levels of protein structurePrimary levelarrangement of amino acid Secondary structure helical coiling of the peptide
Biological Field
Tertiary structure spatial relationship of different secondary structures Quaternary structure
How can we stabilize the protein structure???
Biological Field
• Polypeptide is a long chain molecule
• Dipole is present in polypeptide• Interactions including Dipole –
dipole interaction stabilize the structure
Biological Field
• Example: HaemoglobinConsists of four protein
subunits + haem moleculeFormation of
haemoglobin involved dipole-dipole interaction
Dipole-dipole interaction allow the haemoglobin to take its final shape
Acknowledgement
• Wikipedia (http://en.wikipedia.org/• http://www.gullwinguk.com• http://bucarotechelp.com/computers/
anatomy/91060003.asp
The End
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