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Probing the use of long lived intra-ligand π-π * excited states for photocatalytic systems: a study of the photophysics and photochemistry of [ReCl(CO)3(dppz-(CH3)2)]

Summers, Peter A.; Calladine, James A.; Ibrahim, Nasiru; Kusumo, Kennedy P.; Clark, Charlotte A.; Sun, Xue-Z.; Hamilton, Michelle L.; Towrie, Michael; McMaster, Jonathan; Schröder, Martin; George, Michael W.

Authors

Peter A. Summers

James A. Calladine

Nasiru Ibrahim

Kennedy P. Kusumo

Charlotte A. Clark

Xue-Z. Sun

Michelle L. Hamilton

Michael Towrie

Jonathan McMaster

Martin Schröder

Michael W. George



Abstract

We report the excited state photophysics and photochemistry of [ReCl(CO)3(dppz-(CH3)2)] (dppz-(CH3)2 = 11,12-dimethyl-dipyrido[3,2-a:2’,3’-c]phenazine) in CH3CN using timeresolved infrared (TRIR) and Fourier transform infrared (FTIR) spectroscopy. Excitation of the 1MLCT (metal-to-ligand charge transfer) band of [ReCl(CO)3(dppz-(CH3)2)] populates a 3MLCT excited state which rapidly interconverts on a timescale < 1 ns to a long lived IL (intra-ligand) π-π* excited state with a lifetime of 190 (± 5) ns. In the presence of an electron donor (NEt3), the IL excited state of [ReCl(CO)3(dppz-(CH3)2)] can be reductively quenched to [ReCl(CO)3(dppz-(CH3)2)]− with the radical in the latter localised on the distal phenazine (phz) portion of the dppz ligand. The phz based electron in [ReCl(CO)3(dppz-(CH3)2)]− has minimal interaction with the rhenium metal centre which increases the stability of the photosensitiser in its reduced form. In non-dried, non-degassed CH3CN (1 M NEt3), [ReCl(CO)3(dppz-(CH3)2)]− shows no significant change in the carbonyl region of the IR spectrum for at least 2 hours during continuous photolysis. In addition, we investigate the use of [ReCl(CO)3(dppz-(CH3)2)]− to reduce the previously studied catalyst [NiFe2], with facile electron transfer from [ReCl(CO)3(dppz-(CH3)2)]− to form [NiFe2]–.

Journal Article Type Article
Publication Date Feb 17, 2017
Journal Polyhedron
Print ISSN 0277-5387
Electronic ISSN 0277-5387
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 123
Pages 259-264
APA6 Citation Summers, P. A., Calladine, J. A., Ibrahim, N., Kusumo, K. P., Clark, C. A., Sun, X., …George, M. W. (2017). Probing the use of long lived intra-ligand π-π * excited states for photocatalytic systems: a study of the photophysics and photochemistry of [ReCl(CO)3(dppz-(CH3)2)]. Polyhedron, 123, 259-264. https://doi.org/10.1016/j.poly.2016.11.005
DOI https://doi.org/10.1016/j.poly.2016.11.005
Keywords Rhenium ; Time-resolved IR ; Photophysics ; Intra-ligand excited state ; Reductive quenching
Publisher URL http://www.sciencedirect.com/science/article/pii/S0277538716305836?via%3Dihub
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0
Additional Information This article is maintained by: Elsevier; Article Title: Probing the use of long lived intra-ligand π–π* excited states for photocatalytic systems: A study of the photophysics and photochemistry of [ReCl(CO)3(dppz-(CH3)2)]; Journal Title: Polyhedron; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.poly.2016.11.005; Content Type: article; Copyright: © 2016 Published by Elsevier Ltd.

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0





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