Fluorescence quenching of 9-cyanoanthracene by metallo-octaethylporphyrins in cyanobenzene

摘要

Investigations are carried out on the nature of photoinduced electron transfer reactions within some metallo-octaethylporphyrin (zinc octaethylporphyrin and magnesium octaethylporphyrin) donors and acceptor 9-cyanoanthracene in cyanobenzene at 300 K by steady state and time-resolved spectroscopic methods. Acceptor is selectively excited at 366 nm and 374 nm for steady state and time-resolved measurements, respectively, where donor metalloporphyrins possess negligible absorbance. Evidence is found for simultaneous occurrence of Forster's type singlet-singlet energy transfer process along with electron transfer. High exergonic values of Gibbs free energy change for both forward and back electron transfer reactions indicate the possibility of occurrences of these two consecutive processes in the Marcus inverted region.