Rotaxanes and other transition metal-assembled porphyrin arrays for long-range photoinduced charge separation

Bis-porphyrin conjugates have been synthesized for performing long-range photoinduced charge separation. The electron donor is a zinc(II) porphyrin in the excited state and the electron acceptor is a gold(III) porphyrin. These elements or their free-base analogs have been assembled following two different strategies. In a first approach, the porphyrinic subunits, separated by one or more 2,9-diphenyl-1,10-phenanthroline spacers, have been incorporated into rotaxane structures containing up to four threaded macrocycles by copper(I) templated synthesis. In a second approach, a triad having strictly controlled geometry has been prepared following a new gathering strategy. This triad, consisting of two porphyrinic moieties assembled via a central bis(phenyl-terpyridine) ruthenium(II) complex, uses coordination rather than covalent chemistry to interconnect the components. (C) 1998 Elsevier Science S.A. All rights reserved.