TY - JOUR
T1 - Polaronic Mechanism of Vibronic Localization in Mixed-Valence Cation Radicals with a Non-Conjugated Chromophore on the Bridge
AU - Zilberg, Shmuel
AU - Tsukerblat, Boris
AU - Palii, Andrew
N1 - Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023/4/20
Y1 - 2023/4/20
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85152660808&partnerID=8YFLogxK
U2 - 10.1021/acs.jpca.2c07241
DO - 10.1021/acs.jpca.2c07241
M3 - Article
C2 - 37040558
AN - SCOPUS:85152660808
SN - 1089-5639
VL - 127
SP - 3281
EP - 3292
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 15
ER -