Direct Evaluation of Electronic Coupling Mediated by Hydrogen Bonds: Implications for Biological Electron Transfer

• DOI: 10.1126/science.7660123
• Publication Date: 2006-10-27T18:19:42Z
• Authors: Peter J. F. de Rege; Scott A. Williams; Michael J. Therien
• Keywords: Chromophore

Three supramolecular bischromophoric systems featuring zinc(II) and iron(III) porphyrins have been synthesized to evaluate the relative magnitudes of electronic coupling provided by hydrogen, σ, π bonds. Laser flash excitation generates highly reducing singlet excited state (porphinato)zinc chromophore that can subsequently be electron transfer quenched (porphinato)iron(III) chloride moiety. Measurement photoinduced rate constants enables a direct comparison how well these three types chemical interactions facilitate tunneling. In contrast generally accepted theory, modulated hydrogen-bond interface is greater than an analogous composed entirely carbon-carbon σ These results bear considerably on analysis through-protein data as power theory predict path traversed tunneling in biological matrix; moreover, they underscore cardinal role played hydrogen bonds processes.