Microenvironmental Control of Photoinduced Electron Transfer and the Reverse Reactions in Porphyrin–Viologen Linked System

Abstract

Effects of spacer chain length on photoinduced electron transfer in porphyrin–viologen linked system (ZnPCnV) were investigated by laser photolysis. A long-living charge separated state was obtained with ZnPC4V in both homogeneous and bilayer systems, while ZnPC6V and ZnPC8V afforded appreciable charge separated states only in homogeneous system.

Directional photochemical processes with an amphiphilic anthraceno–ruthenium complex in dihexadecyl phosphate vesicles

“…8 Indeed, the transient absorption spectrum § after excitation at 337 nm coincides with that of 3 An (data not shown). According to these observations, it is concluded that excitation, either to MLCT or to 1 An, leads to 3 An.…”

“…2 Another approach would be to connect the components covalently and incorporate them into vesicles with a defined direction by rational design of the hydrophobic-hydrophilic balance. There are only a few reports on covalently linked chromophores in vesicles 3 in spite of the fact that the covalent approach has been met with great success in elucidating factors determining the rate of electron transfer in homogeneous solutions. 4,5 Here we report on vectorial processes effected by a covalently linked anthraceno-ruthenium complex 1 in dihexadecyl phosphate (DHP) vesicles.…”

“…The fluorescence from 1 An is diminished by a factor of 100 in the vesicular solution. The loss of emission may be caused by an enhanced rate for 1 An to 3 An intersystem crossing facilitated by the spin-orbit coupling due to the heavyatom effect of ruthenium. 8 Indeed, the transient absorption spectrum § after excitation at 337 nm coincides with that of 3 An (data not shown).…”

“…The loss of emission may be caused by an enhanced rate for 1 An to 3 An intersystem crossing facilitated by the spin-orbit coupling due to the heavyatom effect of ruthenium. 8 Indeed, the transient absorption spectrum § after excitation at 337 nm coincides with that of 3 An (data not shown). According to these observations, it is concluded that excitation, either to MLCT or to 1 An, leads to 3 An.…”

Synthesis and photophysical properties of porphyrins containing viologen units for ultrafast molecular photonics

“…Tetraarylporphyrins containing one to four viologen units have been extensively investigated. [1][2][3][4][5][6][7][8][9] The viologen units were found to act as fluorescence quenchers for the excited states of porphyrin, increasing the number of appended viologens led to more effective quenching. The influence of the solvent polarity, mutual orientation and separation distance between the electron donor and the electron acceptor, and types of spacer group on the rate of charge separation and charge recombination has been investigated by means of time-resolved fluorescence spectroscopy and ultrafast flash photolysis techniques.…”