Conjugated photoinduced electron transfer

Fullerenes have shown particular promise as acceptors in molecular electronics, and numerous interesting TTF/Cgo ensembles have been reported.42 For example, Orduna and co-workers75,76 prepared the TTF/C60 dyad 13 and observed photoinduced electron-transfer from the TTF to the fullerene. Martin et al 1 observed two separate one-electron transfer events in their conjugated dyads 14 (where n = 2). The TTF-porphyrin-fullerene triad 15, prepared by Carbonera et al.7 showed long-lived photoinduced charge separation. 

Fan L-J, Jones WE Jr (2006) Studies of photoinduced electron transfer and energy migration in a conjugated polymer system for fluorescence tum-on chemosensor applications. J Phys Chem B 110 7777-7782... 

Designing a conjugated polymer sensor based on FQ, however, is not only a matter of making a fluorescent polymer for which the photoinduced electron transfer reaction is energetically favorable. There are other important factors that must be considered and requirements that must be met to rehably detect any analyte of interest, including TNT, from the vapor phase. In the broadest sense, these considerations distill to the two primary considerations for any sensing system, sensitivity and selectivity. 

A few other interesting molecular architectures exhibiting uncharacteristic electrochemical behavior have been constructed on the basis of the methanofullerene building block. These include two methanofullerene-substituted bipyridine ligands complexed to rhenium and ruthenium ((35) and (36) in Fig. 17), which were prepared as possible candidates for photoinduced electron transfer processes [138]. In addition, three fullerene crown ether conjugates ((38), (39), and (40) in Fig. 18) have... 

Fig. 17. Molecular recognition-dependent photochemical molecular devices. Photochemical processes such as energy transfer (ET) or photoinduced electron transfer (PeT) may be induced via association of two (or more) complementary units, each bearing a component of the device the complementary units may be as small as heterocyclic bases or as large as antigen-antibody conjugates.

Specific Aspects of Photoinduced Electron Transfer in Organic 7i-Conjugated Systems... 

Novel hybrid materials have been realized in which fullerenes participate in composite films with 7r-conjugated-polymer electron donors such as oligothio-phenes. Established studies have already shown that the photoinduced electron transfer is rather enhanced between 7r-conjugated polymers and fullerenes, while back electron transfer is considerably slower [145,149,171,172].Electrosynthe-sized polythiophene with pendant fullerene substituents was recently obtained from the corresponding biothiophene-fulleropyrrolidine dyad [173]. The novel material described has the potential of a double-cable polymer, heavily loaded with fullerene electron-conducting moieties. 

Fig. 1.1. Schematic drawing of photoinduced electron transfer between a conjugated polymer and a fullerene...

J. Gao, F. Hide, H. Wang, Efficient photodetectors and photovoltaic cells from composites of fullerenes and conjugated polymers photoinduced electron transfer, Synth. Met. 84 (1997) 979-980. 

A. Harriman, Y. Kubo, J.L. Sessler, Molecular Recognition via Base-Pairing - Photoinduced Electron-Transfer in Hydrogen-Bonded Zinc Porphyrin Benzoquinone Conjugates , J. Am. Chem. Soc., 114, 388 (1992)... 

The free energy for photoinduced electron transfer in hairpin-forming bis-(oligonucleotide) conjugates can be modified by changing either the nucleobase or the linker (Eqs. 5 or 6) [110-112]. Rate constants for charge separation and re-... 

Figure VC-1 Schematic illustration of the photoinduced electron transfer from conjugated semiconducting polymers onto Buckminsterfullerene, C q.

Figure VC-2 Schematic energy band diagram for a photoinduced electron transfer and photoinduced hole transfer between semiconducting conjugated polymers and Buckminsterfullerene, Cfo-...

Topics that have formed the subjects of reviews this year include contemporary issues in electron transport research, dynamics of bimolecular photoelectron transfer reactions, photophysical properties of functionalised fullerene derivatives, carbon-carbon bond formation via radical ions, photoinduced electron transfer processes in ketone, aldehyde, and ester synthesis, photochemical reactions between arenenitriles and benzylic donors, photo-oxidation of conjugated dienes, photoredox reactions of aromatic nitro compounds, electron transfer-mediated photochemistry of some unsaturated nitrogen-containing compounds, reactions of 02( Ag), carbon dioxide activation by aza-macrocyclic complexes, and photochromism of chalcone derivatives. ... 

---