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21 March 2013

Photoinduced electron transfer in an amine-corrole-perylene bisimide assembly: charge separation over terminal components favoured by solvent polarity - Chem. Eur. J. 2012, 18, 14845-14859


Authors: Roman Voloshchuk, Daniel T. Gryko, Maciej Chotkowski, Adina I. Ciuciu, Lucia Flamigni

Abstract:

An assembly consisting of four units: a meso-substituted corrole (C3), perylene bisimide (PI) and two electron-rich triphenylamine (DPA) units has been synthesised. PI is connected through a 1,4-phenylene bridge to C3, whereas the two DPA units are linked to C3 through a diphenyl ether linkage, which was used to connect the various moieties for the first time. Various synthetic strategies were elaborated and the chosen one afforded the final system in six steps in an overall yield of 6%. The resulting assembly, made of three different units, was named a “triad”. Excitation of the corrole (C3) or of the perylene bisimide (PI) units led to the charge separated state DPA-C3+-PI- with a rate k > 1011 s-1 in benzonitrile and dichloromethane and a k on the order of 1010 s-1 in toluene. The latter charge separated state decayed to the ground state with a rate k = 1.8 × 109 s-1 in toluene. In polar solvents benzonitrile and dichloromethane, recombination to the ground state competes with a charge shift to form the distal charge separated state, DPA+-C3-PI-, whose formation occurs with a yield of 50%. Recombination to the ground state of DPA+-C3-PI- has a rate k = 5 × 107 s-1 in DCM and k = 2 × 107 s-1 in benzonitrile.