Electron transfer triggered by optical excitation of phenothiazine-tris(meta-phenylene-ethynylene)-(tricarbonyl)(bpy)(py)rhenium(I)

Bahar Bingöl; Alec C Durrell; Gretchen E Keller; Joshua H Palmer; Robert H Grubbs; Harry B Gray

doi:10.1021/jp3010053

Electron transfer triggered by optical excitation of phenothiazine-tris(meta-phenylene-ethynylene)-(tricarbonyl)(bpy)(py)rhenium(I)

J Phys Chem B. 2013 Apr 25;117(16):4177-82. doi: 10.1021/jp3010053. Epub 2012 May 3.

Authors

Bahar Bingöl¹, Alec C Durrell, Gretchen E Keller, Joshua H Palmer, Robert H Grubbs, Harry B Gray

Affiliation

¹ The Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

PMID: 22533820
DOI: 10.1021/jp3010053

Abstract

We have investigated excited-state electron transfer in a donor-bridge-acceptor complex containing phenothiazine (PTZ) linked via tris(meta-phenylene-ethynylene) to a tricarbonyl(bipyridine)(pyridine)Re(I) unit. Time-resolved luminescence experiments reveal two excited-state (*Re) decay regimes, a multiexponential component with a mean lifetime of 2.7 ns and a longer monoexponential component of 530 ns in dichloromethane solution. The faster decay is attributed to PTZ → *Re electron transfer in a C-shaped PTZ-bridge-Re conformer (PTZ-Re ≈ 7.5 Å). We assign the longer lifetime, which is virtually identical to that of free *Re, to an extended conformer (PTZ-Re > 20 Å). The observed biexponential *Re decay requires that interconversion of PTZ-bridge-Re conformers be slower than 10(6) s(-1).