Journal of the American Chemical Society, Vol.118, No.45, 11194-11207, 1996
Soluble Synthetic Multiporphyrin Arrays .3. Static Spectroscopic and Electrochemical Probes of Electronic Communication
A comprehensive electrochemical (cyclic and square-wave voltammetry, coulometry) and static spectroscopic (absorption, resonance Raman (RR), electron paramagnetic resonance (EPR)) study is reported for a series of dimeric and trimeric porphyrin-based arrays. All the arrays consist of tetraarylporphyrins linked via ethyne groups at the p-positions of the aryl rings. The complexes investigated include zinc-free base and bis-zinc dimers which contain varying degrees of torsional constraint between the porphyrin rings and the aryl group of the linker, and linear and right-angle trimers in which two zinc porphyrins are bridged by either a zinc or free base porphyrin. The spectroscopic studies were performed on singly and multiply oxidized complexes as well as the neutral species. The electrochemical and spectral properties of the arrays indicate that the electronic communication between the macrocycles is relatively weak in the ground and excited electronic states. This communication is through-bond, rather than through-space, and is mediated by the diarylethyne linker.
Keywords:SUBSTITUTED BIPYRIDINE COMPLEXES;LIGHT-HARVESTING ARRAYS;RESONANCE RAMAN-SPECTRA;REDUCTION PRODUCTS;MODEL SYSTEMS;OPTICAL-PROPERTIES;PORPHYRIN DIMERS;INFRARED-SPECTRA;TRIAD MOLECULES;BUILDING-BLOCKS