Polaronic Mechanism of Vibronic Localization in Mixed-Valence Cation Radicals with a Non-Conjugated Chromophore on the Bridge

Shmuel Zilberg, Boris Tsukerblat, Andrew Palii

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

In quest of a controllable intramolecular electron transfer (ET) across a bridge, we study the cation-radical form of the parent 1,4-diallyl-butane (I) and its derivatives (II)−(VI). In these mixed-valence (MV) compounds, the bridge of variable length connecting allyl redox sites can be either saturated (−CH2 CH2−) (I, III, and V) or unsaturated, modified by the π-spacer (−HC═CH−) (II, IV, and VI). Ab initio calculations for the charge delocalized transition structure and for fully optimized localized form of 1,ω-diallyl cation radicals I-VI allowed us to estimate the potential barriers for ET between the terminal allyl groups, vibronic coupling, and ET parameters. The ET barrier in all compounds with the π-fragment on the bridge is shown to be higher with respect to that in the systems with a saturated bridge. We propose a model based on the concept of a specific polaronic effect of the spacer. Charge localization at an allyl group creates an electric field polarizing the π-fragment and the bridge as a whole. The induced dipole moment interacts with the localized charge giving rise to the additional vibronic stabilization in a self-consistent manner without an appreciable change of localized charge. Utilization of this spacer-driven polaronic effect is expected to provide a route to a controllable ET in bridged MV compounds.

Original languageEnglish
Pages (from-to)3281-3292
Number of pages12
JournalJournal of Physical Chemistry A
Volume127
Issue number15
DOIs
StatePublished - 20 Apr 2023

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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