Charge transfer through cross-hyperconjugated versus cross-π-conjugated bridges: An intervalence charge transfer study

Erik Göransson, Rikard Emanuelsson, Kjell Jorner, Todd F. Markle, Leif Hammarström, Henrik Ottosson

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Abstract

Recently there has been much interest in electron transfer and transport through cross-conjugated molecules as interesting test cases for the interplay between molecular and electronic structure as well as potential motifs in the design of new compounds for molecular electronics. Herein we expand on this concept and present the synthesis and characterization of a series of four organic mixed-valence dyads to probe the effect of the bridge structure on the electronic coupling. The electronic coupling between two triarylamine units could be mediated either by cross-hyperconjugation through a saturated ER 2 bridge (E = C or Si, R = alkyl or silyl group), or via a cross-conjugated π-system. The aim of the study is to compare the electron transfer through the various saturated bridges to that of a cross-π- conjugated bridge. The electronic coupling in these mixed-valence compounds was determined by analysis of intervalence charge transfer bands, and was found to be in the range of 100-400 cm-1. A complementary DFT and TD-DFT study indicated that the electronic coupling in the dyads with saturated ER 2 segments is highly conformer dependant. Furthermore, the calculations showed that two types of interactions contribute to the electronic coupling; a through-bond cross-(hyper)conjugation mechanism and a through-space mechanism. Taken together, these findings suggest the possibility for new architectures for molecular electronics applications utilizing cross-hyperconjugation through properly selected saturated segments which have comparable electron transfer characteristics as regular cross-π-conjugated molecules.

Original languageEnglish
Pages (from-to)3522-3532
Number of pages11
JournalChemical Science
Volume4
Issue number9
DOIs
Publication statusPublished - Sep 2013

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Charge transfer
Molecular electronics
Discrete Fourier transforms
Electrons
Molecules
Molecular structure
Electronic structure

ASJC Scopus subject areas

  • Chemistry(all)

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Charge transfer through cross-hyperconjugated versus cross-π-conjugated bridges : An intervalence charge transfer study. / Göransson, Erik; Emanuelsson, Rikard; Jorner, Kjell; Markle, Todd F.; Hammarström, Leif; Ottosson, Henrik.

In: Chemical Science, Vol. 4, No. 9, 09.2013, p. 3522-3532.

Research output: Contribution to journalArticle

Göransson, Erik ; Emanuelsson, Rikard ; Jorner, Kjell ; Markle, Todd F. ; Hammarström, Leif ; Ottosson, Henrik. / Charge transfer through cross-hyperconjugated versus cross-π-conjugated bridges : An intervalence charge transfer study. In: Chemical Science. 2013 ; Vol. 4, No. 9. pp. 3522-3532.
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