The fate of charge separation reactions within a novel synthesized bichromophore in β-cyclodextrin microenvironment

Both steady state and time resolved spectroscopic investigations on a novel synthesized bichromophore 4MBA (4 methoxybenzo[b]thiophene donor (4MBT) is linked with the electron acceptor p-chloroacetophenone (PCA) by an unsaturated olefinic spacer) in aqueous medium demonstrate the formation of two types of isomer. One is due to cis- (folded conformation) and the other corresponds to trans- (extended nature) resulted from intramolecular charge separation reactions both in the ground and excited electronic states. Laser flash photolysis measurements show that the preponderance of trans-type isomer of 4MBA in presence of β-cyclodextrin, due to formation of inclusion complexes, causes the enhancement of the survival duration of charge separated species to large extent (66 μs) minimizing the energy wasting charge recombination process.