Steric effects in photoinduced electron-transfer reactions

Ian Gould, Samir Farid

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Quantum yields for formation of separated radical ions are determined for the electron-transfer reactions of singlet excited cyanoanthracene acceptors with sterically hindered alkylbenzene donors, in acetonitrile. These yields are up to 4 times larger than those for unhindered alkylbenzene donors. The yields are controlled by the competition between separation and return electron transfer in the initially formed radical-ion pairs. From studies of the dependence of the steric effect on the driving force for return electron transfer, it is concluded that the main effect of the steric hindrance is to decrease the magnitude of the electronic coupling matrix element for electron transfer, thus decreasing the return electron transfer rate and increasing the separation yield. The sterically hindered donors can be divided into two groups depending upon whether the substituents on the benzene ring have hydrogens that are capable of hyperconjugative stabilization of the positive charge in the radical cation. The electron transfer reorganization parameters are measurably different for the donors that have these substituents compared to those that lack such hydrogen atoms.

Original languageEnglish (US)
Pages (from-to)13067-13072
Number of pages6
JournalJournal of Physical Chemistry
Volume97
Issue number50
StatePublished - 1993
Externally publishedYes

Fingerprint

electron transfer
Electrons
Hydrogen
Ions
Quantum yield
Benzene
Acetonitrile
acetonitrile
Cations
hydrogen atoms
ions
Stabilization
stabilization
Positive ions
benzene
cations
Atoms
rings
hydrogen
matrices

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Steric effects in photoinduced electron-transfer reactions. / Gould, Ian; Farid, Samir.

In: Journal of Physical Chemistry, Vol. 97, No. 50, 1993, p. 13067-13072.

Research output: Contribution to journalArticle

Gould, Ian ; Farid, Samir. / Steric effects in photoinduced electron-transfer reactions. In: Journal of Physical Chemistry. 1993 ; Vol. 97, No. 50. pp. 13067-13072.
@article{bd678199a6dc49548357ab783b6fa806,
title = "Steric effects in photoinduced electron-transfer reactions",
abstract = "Quantum yields for formation of separated radical ions are determined for the electron-transfer reactions of singlet excited cyanoanthracene acceptors with sterically hindered alkylbenzene donors, in acetonitrile. These yields are up to 4 times larger than those for unhindered alkylbenzene donors. The yields are controlled by the competition between separation and return electron transfer in the initially formed radical-ion pairs. From studies of the dependence of the steric effect on the driving force for return electron transfer, it is concluded that the main effect of the steric hindrance is to decrease the magnitude of the electronic coupling matrix element for electron transfer, thus decreasing the return electron transfer rate and increasing the separation yield. The sterically hindered donors can be divided into two groups depending upon whether the substituents on the benzene ring have hydrogens that are capable of hyperconjugative stabilization of the positive charge in the radical cation. The electron transfer reorganization parameters are measurably different for the donors that have these substituents compared to those that lack such hydrogen atoms.",
author = "Ian Gould and Samir Farid",
year = "1993",
language = "English (US)",
volume = "97",
pages = "13067--13072",
journal = "Journal of Physical Chemistry",
issn = "0022-3654",
publisher = "American Chemical Society",
number = "50",

}

TY - JOUR

T1 - Steric effects in photoinduced electron-transfer reactions

AU - Gould, Ian

AU - Farid, Samir

PY - 1993

Y1 - 1993

N2 - Quantum yields for formation of separated radical ions are determined for the electron-transfer reactions of singlet excited cyanoanthracene acceptors with sterically hindered alkylbenzene donors, in acetonitrile. These yields are up to 4 times larger than those for unhindered alkylbenzene donors. The yields are controlled by the competition between separation and return electron transfer in the initially formed radical-ion pairs. From studies of the dependence of the steric effect on the driving force for return electron transfer, it is concluded that the main effect of the steric hindrance is to decrease the magnitude of the electronic coupling matrix element for electron transfer, thus decreasing the return electron transfer rate and increasing the separation yield. The sterically hindered donors can be divided into two groups depending upon whether the substituents on the benzene ring have hydrogens that are capable of hyperconjugative stabilization of the positive charge in the radical cation. The electron transfer reorganization parameters are measurably different for the donors that have these substituents compared to those that lack such hydrogen atoms.

AB - Quantum yields for formation of separated radical ions are determined for the electron-transfer reactions of singlet excited cyanoanthracene acceptors with sterically hindered alkylbenzene donors, in acetonitrile. These yields are up to 4 times larger than those for unhindered alkylbenzene donors. The yields are controlled by the competition between separation and return electron transfer in the initially formed radical-ion pairs. From studies of the dependence of the steric effect on the driving force for return electron transfer, it is concluded that the main effect of the steric hindrance is to decrease the magnitude of the electronic coupling matrix element for electron transfer, thus decreasing the return electron transfer rate and increasing the separation yield. The sterically hindered donors can be divided into two groups depending upon whether the substituents on the benzene ring have hydrogens that are capable of hyperconjugative stabilization of the positive charge in the radical cation. The electron transfer reorganization parameters are measurably different for the donors that have these substituents compared to those that lack such hydrogen atoms.

UR - http://www.scopus.com/inward/record.url?scp=33751385206&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33751385206&partnerID=8YFLogxK

M3 - Article

VL - 97

SP - 13067

EP - 13072

JO - Journal of Physical Chemistry

JF - Journal of Physical Chemistry

SN - 0022-3654

IS - 50

ER -