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)]

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

doi:10.1016/j.poly.2016.11.005

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)]

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

Department of Chemical and Environmental Engineering

Research output: Journal Publication › Article › peer-review

5 Citations (Scopus)

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 time-resolved infrared (TRIR) and Fourier transform infrared (FTIR) spectroscopy. Excitation of the¹MLCT (metal-to-ligand charge transfer) band of [ReCl(CO)₃(dppz-(CH₃)₂)] populates a³MLCT excited state which rapidly interconverts on a timescale <1 ns to a long lived IL (intra-ligand) ππ^∗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 h 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]⁻.

Original language	English
Pages (from-to)	259-264
Number of pages	6
Journal	Polyhedron
Volume	123
DOIs	https://doi.org/10.1016/j.poly.2016.11.005
Publication status	Published - 2017

Keywords

Intra-ligand excited state
Photophysics
Reductive quenching
Rhenium
Time-resolved IR

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry
Materials Chemistry

Access to Document

10.1016/j.poly.2016.11.005

Cite this

Summers, P. A., Calladine, J. A., Ibrahim, N., Kusumo, K. P., Clark, C. A., Sun, X. Z., Hamilton, M. L., Towrie, M., McMaster, J., Schröder, M., & 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

@article{cab9a84277fa4167a485b329235a0e3a,

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)]",

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 time-resolved infrared (TRIR) and Fourier transform infrared (FTIR) spectroscopy. Excitation of the1MLCT (metal-to-ligand charge transfer) band of [ReCl(CO)3(dppz-(CH3)2)] populates a3MLCT excited state which rapidly interconverts on a timescale <1 ns to a long lived IL (intra-ligand) ππ∗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 h 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]−.",

keywords = "Intra-ligand excited state, Photophysics, Reductive quenching, Rhenium, Time-resolved IR",

author = "Summers, {Peter A.} and Calladine, {James A.} and Nasiru Ibrahim and Kusumo, {Kennedy P.} and Clark, {Charlotte A.} and Sun, {Xue Z.} and Hamilton, {Michelle L.} and Michael Towrie and Jonathan McMaster and Martin Schr{\"o}der and George, {Michael W.}",

note = "Publisher Copyright: {\textcopyright} 2016",

year = "2017",

doi = "10.1016/j.poly.2016.11.005",

language = "English",

volume = "123",

pages = "259--264",

journal = "Polyhedron",

issn = "0277-5387",

publisher = "Elsevier Ltd.",

}

Summers, PA, Calladine, JA, Ibrahim, N, Kusumo, KP, Clark, CA, Sun, XZ, Hamilton, ML, Towrie, M, McMaster, J, Schröder, M & George, MW 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, vol. 123, pp. 259-264. https://doi.org/10.1016/j.poly.2016.11.005

TY - JOUR

T1 - Probing the use of long lived intra-ligand π–π*excited states for photocatalytic systems

T2 - A study of the photophysics and photochemistry of [ReCl(CO)3(dppz-(CH3)2)]

AU - Summers, Peter A.

AU - Calladine, James A.

AU - Ibrahim, Nasiru

AU - Kusumo, Kennedy P.

AU - Clark, Charlotte A.

AU - Sun, Xue Z.

AU - Hamilton, Michelle L.

AU - Towrie, Michael

AU - McMaster, Jonathan

AU - Schröder, Martin

AU - George, Michael W.

PY - 2017

Y1 - 2017

N2 - 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 time-resolved infrared (TRIR) and Fourier transform infrared (FTIR) spectroscopy. Excitation of the1MLCT (metal-to-ligand charge transfer) band of [ReCl(CO)3(dppz-(CH3)2)] populates a3MLCT excited state which rapidly interconverts on a timescale <1 ns to a long lived IL (intra-ligand) ππ∗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 h 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]−.

AB - 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 time-resolved infrared (TRIR) and Fourier transform infrared (FTIR) spectroscopy. Excitation of the1MLCT (metal-to-ligand charge transfer) band of [ReCl(CO)3(dppz-(CH3)2)] populates a3MLCT excited state which rapidly interconverts on a timescale <1 ns to a long lived IL (intra-ligand) ππ∗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 h 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]−.

KW - Intra-ligand excited state

KW - Photophysics

KW - Reductive quenching

KW - Rhenium

KW - Time-resolved IR

UR - http://www.scopus.com/inward/record.url?scp=85007302222&partnerID=8YFLogxK

U2 - 10.1016/j.poly.2016.11.005

DO - 10.1016/j.poly.2016.11.005

M3 - Article

AN - SCOPUS:85007302222

SN - 0277-5387

VL - 123

SP - 259

EP - 264

JO - Polyhedron

JF - Polyhedron

ER -