microscale synthesis of porphyrin...
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Microscale SynthesisMicroscale Synthesisof
Porphyrin Complexes
The Porphyrin Chromophore
Porphyrins are particularly attractive for many applications due to their
rigid planar geometry rigid-planar geometry
redox stability
intense electronic absorption
strong emission
small HOMO-LUMO energy gap
tunable optical and redox properties
Zinc‐5,10,15,20‐tetraphenylporphyrin
UV‐Vis absorption, Fluorescencese Emission and Cyclic Voltammetry of ZnTPP
Photosynthesis( 6CO2 + 6H2O + hv → (CH2O)6 + 6O2 )( 6CO2 + 6H2O + hv → (CH2O)6 + 6O2 )
Light-Harvesting(energy transfer) Reaction Center
(charge-separation via e- transfer)
From Photosynthesis to Dye Sensitized Solar Cells (DSC’s)
OTE TiO2 Dye-sensitizer Electrolyte Counter-electrode
CB -0.5S*charge
separatione-
E0.0
0vsN
HE
hv e-
Red Oxe-
Voc
charge
recombination
EF
0.5
1.0
E(V
)v
S0/S+
e- Mediator
dif f usion
e-
• Chare separation and charge recombination competitive processes
O’Regan B.; Graetzel M. Nature 1991, 353, 737.Graetzel M. Nature 2001, 414, 338.
Porphyrins and Semiconductor Sensitization
ETCPP* ~ -0.6 eV vs. ECB TiO2
Maximum 3 % IPCE = 55 % ff = 70 %Maximum ~ 3 % , IPCE = 55 % , ff = 70 %
Isc = 6 mAcm-2 , Voc = 485 mV
Cherian S.; Wamser C. C. J. Phys. Chem. B 2000, 104, 3624.
Effect of the Spacer Length and Anchoring Group Position
p-ZnTCPP-[S] m-ZnTCPP-[S] m-ZnTCP2P-[S]m-ZnTC(PEP)P-[S]In
tens
ity
ZrO2/Glass
( ) [ ]
mal
ised
Em
issi
on
550 600 650 700 750 800
Nor
m
Wavelength (nm)
40
50
60
on TiO /FTO
p-ZnTCPP-[S] m-ZnTCPP-[S] m-ZnTCP2P-[S] m-ZnTC(PEP)P-[S]
E (%
)
0
10
20
30 on TiO2/FTO
IPC
E
Rochford J.; Chu D.; Hagfeldt A.; Galoppini E. J. Am. Chem. Soc. , 2007, 129, 4655.
400 500 600 700 8000
Wavelength (nm)
Porphyrin Catalysts for CO2 Reduction
• The metalloporphyrins and related metallo‐macrocycles studied for CO2 reduction reactivity includemetalloporphyrins (MP), metallocorrins (MN), metallophthalocyanines (MPc), and metallocorroles(MC), Figure 4, where M = Fe or Co.
• The active catalytic states as identified by cyclic voltametry have the metal in the formal oxidation• The active catalytic states as identified by cyclic voltametry have the metal in the formal oxidationstate of zero for porphyrins [M0P]2‐ and corrins [M0N]2‐, +1 for corroles [MIC]2‐, and +1 with areduced phthalocyanine ring [MIPc•‐]2‐.
Morris et. al Acc. Chem. Res., 2009, 42 (12), pp 1983–1994
Mechanism for CO2 Reduction
Porphyrin Catalysts for O2 Activation
Matsui et. al Inorg. Chem., 2010, 49 (8), pp 3602–3609
Halime et. al Inorg. Chem., 2010, 49 (8), pp 3629–3645
Synthetic Methods
NH
R
R NHNH
Ph
PhPh
R
R R
R
+Propionic acid, Ar
CHO
NH NHPh
Ph
Ph
R
RR
R
+relux, 30 min
PhR R
R = H, Me R = H - meso-TetraphenylporphyrinogenR = Me - -octamethyl-meso-tetraphenylporphyrinogen
N NH
NNHPhPh
R
R R
R
O2
N NH
Ph
R
RR
R
R = H - meso-TetraphenylporphyrinR H meso Tetraphenylporphyrin R = Me - -octamethyl-meso-tetraphenylporphyrin
A.D. Adler, F.R. Longo, J.D. Finarelli, J. Goldmacher, J. Assour, L. Korsakoff, J. Org. Chem. 1967, 32, 476.
Synthetic Methods
NH NH
NHNH
H
H
H
Ph
Ph
Ph
NH
+TFA or BF3.OEt, Ar
CH2Cl2 250C
4
+ 4 H20NH
H Ph
CHO
5,10,15,20-Tetraphenylporphyrinogen
4
O
O
Cl
Cl
CN
CNCH2Cl2 250C
3
NNH
PhOH
Cl CN
DDQ
3
N NHPh
Ph
PhOH
Cl CN
DDQH2
5,10,15,20-Tetraphenylporphyrin (TPP)
J. S. Lindsey, I. C. Schreiman, H.C. Hsu, P. Kearney, A. M. Marguerettaz, J. Org. Chem. 1987, 52, 827