Acta Phys. -Chim. Sin. ›› 2001, Vol. 17 ›› Issue (10): 924-930.doi: 10.3866/PKU.WHXB20011012

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Solvent Reorganization Energy of Organic Conjugated Systems in Electron Transfer Reactions

Min Wei;Sun Lin   

  1. Department of Applied Chemistry,College of Chemistry and Molecular Engineering,Peking University,Beijing 100871
  • Received:2001-03-21 Revised:2001-07-02 Published:2001-10-15
  • Contact: Min Wei

Abstract: In the calculation of solvent reorganization energy by Marcus′s twosphere model,we presented a flat sphere model based on benzenesolvent system′s exact geometry structure to describe the electron cloud of conjugated systems.We figured out the radii of electron donors and acceptors by using statistics method,after AM1 geometry optimization,and then calculated λs.Besides,according to Miller′s experiment and consulting McHale and other researchers′ Raman Spectrometry results,we supposed that the solute molecular low frequency torsion gave no contribution to λv when the frequency was too small and the λs obtained from flat sphere model had contained low frequency contribution.This revised λs was in agreement with the value figured out by subtracting revised λv from experimental λ value.By comparing them,we found that the distance between donor and acceptor,the alteration of acceptor and solvent affected the deviation of calculated λs from experiment values.Finally,we confirmed that the DA coupling,super exchange mediated by solvent molecule,surface interaction of solventsolute molecules and other similar quantum effects would reduce the classical value of λs,thus contribute to ET reaction.Our results proved the deviation of practical reaction systems to the continuum dielectric theory and reflected the necessity of describing the behaviors of solvent and solute molecules using molecular model.

Key words: Solvent reorganization energy, Radius of electron donor and acceptor,  Conjugated molecule, Marcus theory, Electron transfer