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Towards panchromatic Fe(II) NHC sensitizers via HOMO inversion

Lookup NU author(s): Professor Thomas Penfold



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


A combined experimental and theoretical study of iron(II) complexes with pyridyl N-heterocyclic carbene ligands is presented, with a new focus on the effect of extending the ligands with thiophenes in variable number. In agreement with recent theoretical predictions by the Jakubikova group, these ligands induce a substantial mixture of the occupied t2g and pi HOMO orbitals, as manifested by a near 80 nm red-shift of the 1MLCT transition and a 2-3 fold increase of the molar extinction coefficient. The thiophene moieties allow for a delocalisation of the MLCT state on the ligands, which results in excited state lifetimes in the 13-18 ps range, almost twice as much as for the reference compound lacking the thienyl substituents. Relaxation into 3MC states remains the main 3MLCT quenching mechanism, and the effect of the number of thiophenes in lengthening the 3MLCT lifetime is qualitatively consistent with a reduced 3MLCT-3MC energy gap.

Publication metadata

Author(s): Marri AR, Marekha BA, Penfold TJ, Haacke S, Gros PC

Publication type: Article

Publication status: Published

Journal: Inorganic Chemistry Frontiers

Year: 2023

Volume: 10

Pages: 118-126

Print publication date: 07/01/2023

Online publication date: 14/11/2022

Acceptance date: 10/11/2022

Date deposited: 15/11/2022

ISSN (electronic): 2052-1553

Publisher: Royal Society of Chemistry


DOI: 10.1039/D2QI01903E


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