Visualizing Thermally Activated Conical Intersections Governing Non-Radiative Triplet Decay in a Ni(II) Porphyrin-Nanographene Conjugate with Variable Temperature Transient Absorption Spectroscopy.

Autor:	Garcia-Orrit S; Madrid Institute for Advanced Studies, IMDEA Nanociencia, c/Faraday 9, Campus de Cantoblanco, Madrid 28049, Spain., Vega-Mayoral V; Madrid Institute for Advanced Studies, IMDEA Nanociencia, c/Faraday 9, Campus de Cantoblanco, Madrid 28049, Spain., Chen Q; Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany., Serra G; Dipartimento di Chimica, Materiali ed Ingegneria Chimica 'G.Natta', Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)., Guizzardi M; Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy., Romano V; Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy., Dal Conte S; Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy., Cerullo G; Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy., Di Mario L; Photophysics and OptoElectronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 3, 9747 AG, Groningen, The Netherlands., Kot M; Photophysics and OptoElectronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 3, 9747 AG, Groningen, The Netherlands., Loi MA; Photophysics and OptoElectronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 3, 9747 AG, Groningen, The Netherlands., Narita A; Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.; Organic and Carbon Nanomaterials Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan., Müllen K; Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.; Institute for Physical Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany., Tommasini M; Dipartimento di Chimica, Materiali ed Ingegneria Chimica 'G.Natta', Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)., Cabanillas-González J; Madrid Institute for Advanced Studies, IMDEA Nanociencia, c/Faraday 9, Campus de Cantoblanco, Madrid 28049, Spain.
Jazyk:	angličtina
Zdroj:	The journal of physical chemistry letters [J Phys Chem Lett] 2024 Oct 17; Vol. 15 (41), pp. 10366-10374. Date of Electronic Publication: 2024 Oct 07.
DOI:	10.1021/acs.jpclett.4c02712
Abstrakt:	Metalloporphyrins based on open-shell transition metals, such as Ni(II), exhibit typically fast excited-state relaxation. In this work, we shed light into the nonradiative relaxation mechanism in a nanographene-Ni(II) porphyrin conjugate. Variable temperature transient absorption and global fit analysis are combined to produce a picture of the relaxation pathways. At room temperature, photoexcitation of the lowest π-π* transition is followed by vibrational cooling in 1.6 ps, setting a short 20 ps temporal window wherein a small fraction of relaxed singlets radiatively decay to the ground state before intersystem crossing proceeds. Following intersystem crossing, triplets relax rapidly to the ground state (S 0 ) in a few tens of picoseconds. By performing measurements at low temperature, we provide evidence for a competition between two terminal relaxation pathways from the lowest (metal-centered) triplet to the ground state: a slow ground state relaxation process proceeding in time scales beyond 1.6 ns and a faster pathway dictated by a sloped conical intersection, which is thermally accessible at room temperature from the triplet state. The overall triplet decay at a given temperature is dictated by the interplay of these two contributions. This observation bears significance in understanding the underlying fast relaxation processes in Ni-based molecules and related transition metal complexes, opening avenues for potential applications for energy harvesting and optoelectronics.
Databáze:	MEDLINE
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