Unusually high energy barriers for internal conversion in a {Ru(bpy)} chromophore

Cotic A, Veys K, Escudero D, Cadranel A (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Physical Chemistry Chemical Physics Royal Society of Chemistry

DOI: 10.1039/d2cp03160d

Abstract

Internal conversion (IC) coupled to vibrational relaxation (VR) in molecular chromophores is a source of major energy losses in natural and artificial solar-to-chemical energy conversion schemes. The development of anti-Kasha chromophores, where dissipative IC channels are blocked, is a promising strategy to boost energy conversion efficiencies. In this contribution, we demonstrate the presence of an unusually high kinetic barrier for IC in [Ru(tpm)(bpy)(NCS)](+) (RuNCS), where tpm is tris(1-pyrazolyl)methane and bpy is 2,2 '-bipyridine, by means of an arsenal of temperature-dependent spectroscopic methods including nanosecond and femtosecond transient absorption spectroscopies. These studies are complemented with theoretical investigations, that provide a detailed atomistic description of the dissipation process, including the electronic structures of the excited states involved. The observed IC is mainly a hole reconfiguration within the octahedral t(2g) set of the Ru ion, with contributions from a Ru to NCS charge transfer. Thus, in a Marcus picture, inner and outer reorganizations contribute to the observed barrier. The results presented here show that wavefunction symmetry within a molecular chromophore can be exploited to inhibit dissipative IC. Finally, guidelines for the design of anti-Kasha chromophores that prevent dissipation in energy conversion schemes, based on minimum energy conical intersection calculations, are provided.

Authors with CRIS profile

Alejandro Cadranel Lehrstuhl für Physikalische Chemie I

Involved external institutions

Katholieke Universiteit Leuven (KUL) / Catholic University of Leuven BE Belgium (BE) Universidad de Buenos Aires (UBA) / University of Buenos Aires AR Argentina (AR)

How to cite

APA:

Cotic, A., Veys, K., Escudero, D., & Cadranel, A. (2022). Unusually high energy barriers for internal conversion in a {Ru(bpy)} chromophore. Physical Chemistry Chemical Physics. https://dx.doi.org/10.1039/d2cp03160d

MLA:

Cotic, Agustina, et al. "Unusually high energy barriers for internal conversion in a {Ru(bpy)} chromophore." Physical Chemistry Chemical Physics (2022).

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