Intramolecular shielding of charge-transfer excited states of surfactant active rhenium(I) photosensitizers

Abstract

Excited-state electron-transfer processes involving organized assemblies are currently under active study. Such systems show promise for increasing the efficiency of energy-storage reactions. In particular, surfactant-active analogues of Ru(bpy)/sub 3//sup 2 +/ (bpy = 2,2'-bipyridine) with long hydrophobic alkyl chains have been used to modify sensitizer chemistry and photophysics. Reported here is an investigation of a new series of surfactant-active Re(I) photosensitizers: fac-((bpy)Re/sup 1/(CO)/sub 3/L)/sup +/ (L = NC(CH/sub 2/)/sub n/CH/sub 3/, n = 0,2,5,6,7,9,10,13,17). These systems exhibit intense d-..pi..* metal to ligand charge-transfer (MLCT) emissions in fluid solutions similar to the parent acetonitrile complex (n = 0). A dramatic example of an intramolecular perturbation of CT excited-state properties by the electronically passive alkyl chain is examined.