TY - JOUR

T1 - Confinement of the Triplet States in π-Conjugated BODIPY Dimers Linked with Ethynylene or Butadiynylene Bridges: A Different View on the Effect of Symmetry

AU - Zhang, Xue

AU - Ivanov, Mikhail

AU - Wang, Zhijia

AU - Bousquet, Manon H.E.

AU - Liu, Xi

AU - Wan, Yan

AU - Zhao, Jianzhang

AU - Barbon, Antonio

AU - Escudero, Daniel

AU - Jacquemin, Denis

AU - Fedin, Matvey

N1 - Funding Information: J.Z. would like to thank the NSFC (U2001222), the Fundamental Research Funds for the Central Universities (DUT22LAB610) and the State Key Laboratory of Fine Chemicals for financial support. The authors gratefully acknowledge the CCIPL center installed in Nantes (France) for the generous allotment of computer time. M.F. and M.I. thank the Ministry of Science and Higher Education of the Russian Federation (Grant No. 075‐15‐2020‐779). D.J. is deeply indebted to the GliCid/CCIPL center installed in Nantes for the very generous allocation of computational resources. We are grateful to Prof. Xiaolian Li at Dalian University of Technology for supply of the liquid crystal. Open Access funding provided by Università degli Studi di Padova within the CRUI‐CARE Agreement. Publisher Copyright: © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.

PY - 2022/12/5

Y1 - 2022/12/5

N2 - Understanding the impact of the excited state wavefunction confinement is crucial for the engineering of the photophysical properties and applications of organic chromophores. In the present contribution, the localization of the triplet state wavefunctions of some symmetric ethyne/butadiyne bridged BODIPY dimers and asymmetric BODIPY derivatives presenting extended π-conjugation frameworks is studied with time-resolved electron paramagnetic resonance spectroscopy and time-dependent density functional theory computations. Based on the Zero Field Splitting D parameters, we conclude that the triplet state wavefunctions are highly localized on one BODIPY unit in the symmetric dimers, which is consistent with the ab initio modelling that finds delocalized triplet state destabilized by 12–14 kcal mol−1 as compared to its localized counterpart. The result provides a new insight into the study of triplet excited state confinement and the design of molecular wires or photosensitizers for photovoltaics and photocatalysis.

AB - Understanding the impact of the excited state wavefunction confinement is crucial for the engineering of the photophysical properties and applications of organic chromophores. In the present contribution, the localization of the triplet state wavefunctions of some symmetric ethyne/butadiyne bridged BODIPY dimers and asymmetric BODIPY derivatives presenting extended π-conjugation frameworks is studied with time-resolved electron paramagnetic resonance spectroscopy and time-dependent density functional theory computations. Based on the Zero Field Splitting D parameters, we conclude that the triplet state wavefunctions are highly localized on one BODIPY unit in the symmetric dimers, which is consistent with the ab initio modelling that finds delocalized triplet state destabilized by 12–14 kcal mol−1 as compared to its localized counterpart. The result provides a new insight into the study of triplet excited state confinement and the design of molecular wires or photosensitizers for photovoltaics and photocatalysis.

KW - Electron Paramagnetic Resonance

KW - Electron Spin

KW - Intersystem Crossing

KW - Triplet State

KW - Zero Field Splitting

UR - http://www.scopus.com/inward/record.url?scp=85141125927&partnerID=8YFLogxK

U2 - 10.1002/anie.202210419

DO - 10.1002/anie.202210419

M3 - Article

C2 - 36216789

AN - SCOPUS:85141125927

VL - 61

SP - e202210419

JO - Angewandte Chemie - International Edition

JF - Angewandte Chemie - International Edition

SN - 1433-7851

IS - 49

M1 - e202210419

ER -