Photo electron transfer intermolecular

Intermolecular photo-oxidation-reduction reactions involve a light initiated electron transfer between a complex and any other suitable molecule available in the medium. An oxidized or a reduced form of the complex may be obtained. 

In a supramolecular approach to fullerene-porphyrin hybrids, the assembly of a rigidly connected dyad, in which a zinc tetraphenylporphyrin, Zn(TPP), is noncovalently linked to a C60 derivative via axial pyridine coordination to the metal, was reported [219-222]. Photo excitation of the dyad Zn-complex led to electron transfer with very long lifetimes of the charge-separated pairs, as revealed by optical spectroscopy and confirmed by time-resolved electron paramagnetic resonance spectroscopy. Accordingly, two different solvent-dependent pathways can be considered for the electron-transfer processes. Either the excitation of the porphyrin chromophore is followed by fast intramolecular electron transfer inside the complex, or alternatively the free porphyrin is excited undergoing intermolecular electron transfer when the acceptor molecules ap-... 

In this section an illustrative discussion on kinetics of photopolymerization initiated via an intermolecular photoinduced electron transfer for a dye-tertiary aromatic amine initiating photo-redox couple [193] and for 4-carboxybenzophenone-sulfur-containing carboxylic acids initiating systems will be presented. 

Intermolecular Photo-Induced Electron Transfer. Picosecond absorption spectroscopy has also been applied recently to studies of intermolecular electron transfer on the picosecond time scale.(34) As in the previously described study of rhodopsin, the photo-induced intermolecular electron transfer between chloranil (CHL) and the arenes, naphthalene (NAP), 9,10-dihydrophenanthrene (DHP), and indene (IN) was studied by means of picosecond absorption spectroscopy which utilizes an OMCD. Difference absorption spectra of samples of CHL and one of these particular arenes in acetonitrile were measured at selected delay times after excitation at 355-nm with 25-ps FWHM laser pulses. These picosecond spectroscopic studies revealed information about the mechanism of intermolecular electron transfer and subsequent radical ion formation that was not possible in previous spectroscopic studies performed on the nanosecond (35-37) and microsecond (38,39) time scales. 

Volume 1 contains 15 chapters on the recent developments in charge-transfer salts, fullerenes, photoconductors and molecular conductors. The topics covered include electron acceptor molecules, photo-induced intermolecular electron transfer systems, perylene based conductors, tetrachalcogenafulvalenes, metal 1,2-dichaIcogenoIenes and their conductive salts, conductive hetero-TCNQs (tetracyano-p-quinodi-methane derivatives), molecular metals and superconductors based on transition metal complexes. 

One report demonstrated the use of a non-covalently bound riboflavin for photo-induced intermolecular electron transfer from the isoal-loxazine moiety of the flavin to the heme group of CYP2B4 [275]. Although an effect of different substrates on the electron transfer rate in this artificial system was observed, no product formahon was reported. 

Vision involves cis-trans photoisomerization of a chromophore and many studies have been done using different models/ For example, a CASSCF/AMBER procedure has been used to study the nonadiabatic dynamics of retinal in rhodopsin proteins/ In another study, a simple model of a photosynthetic center was examined by Worth and Cederbaum. They proposed that the presence of conical intersections facilitated the long-range intermolecular photo-initiated electron transfer between the protein s porphyrin and a nearby quinone. Semiempirical methods and QM/MM methods have been developed by Martinez and coworkers " to study the cis-trans isomerization dynamics of the Green Fluorescent Protein chromophore in solution, which occurs through conical intersections.The chromophore in this protein consists of two rings connected with a double bond and has been studied in vacuo as well. ... 

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