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Title: Ultrafast dynamics in the metal-to-ligand charge transfer excited-state evolution of [Ru(4,4{prime}-diphenyl-2,2{prime}-bipyridine){sub 3}]{sup 2+}

Abstract

The transition metal complexes [Ru(dmb){sub 3}]{sup 2+}, where dmb is 4,4{prime}-dimethyl-2,2{prime}-bipyridine and dpb is 4,4{prime}-diphenyl-2,2{prime}-bipyridine, have been studied by femtosecond visible electronic absorption spectroscopy. Spectroelectrochemical measurements in conjunction with nanosecond time-resolved absorption spectroscopy allow for the assignment of various features in the excited-state differential absorption spectra as both ligand-based {pi}* {l{underscore}arrow} {pi}* and ligand-to-metal charge transfer (LMCT) in nature. A unique absorptive feature centered at {approximately} 530 nm in [Ru(dpb){sub 3}]{sup 2+} was identified as an optical marker for the thermalized (and hence fully intraligand delocalized) excited state. Single wavelength and full spectrum transient absorption data were obtained on both molecules in CH{sub 3}CN solution at room temperature following metal-to-ligand charge transfer (MLCT) excitation at 400 nm. Data on [Ru(dmb){sub 3}]{sup 2+} at 532 nm, a region of net excited-state absorption, revealed biphasic decay kinetics ({approximately}120 fs and 5 ps) attributed to a combination of {sup 1}MLCT {r{underscore}arrow} {sup 3}MLCT intersystem crossing and vibrational cooling dynamics. Dynamics for [Ru(dpb){sub 3}]{sup 2+} under identical conditions revealed biphasic rise times in the region of the ligand-based {pi}* {l{underscore}arrow} {pi}* absorption at {lambda}{sub probe} = 532 nm. Although the origin of the gas component ({approximately}200 fs) is not yet clear, the ca. 2more » ps rise is assigned to rotation of the peripheral aryl ring and thus corresponds to the time scale for intraligand electron delocalization.« less

Authors:
;
Publication Date:
Research Org.:
Univ. of California, Berkeley, CA(US)
Sponsoring Org.:
USDOE
OSTI Identifier:
20001109
DOE Contract Number:  
FG03-96ER14665
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory
Additional Journal Information:
Journal Volume: 103; Journal Issue: 42; Other Information: PBD: 21 Oct 1999; Journal ID: ISSN 1089-5639
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; RUTHENIUM COMPLEXES; BIPYRIDINES; PHENYL RADICALS; LIGANDS; CHARGE TRANSPORT; DYNAMICS

Citation Formats

Damrauer, N H, and McCusker, J K. Ultrafast dynamics in the metal-to-ligand charge transfer excited-state evolution of [Ru(4,4{prime}-diphenyl-2,2{prime}-bipyridine){sub 3}]{sup 2+}. United States: N. p., 1999. Web. doi:10.1021/jp9927754.
Damrauer, N H, & McCusker, J K. Ultrafast dynamics in the metal-to-ligand charge transfer excited-state evolution of [Ru(4,4{prime}-diphenyl-2,2{prime}-bipyridine){sub 3}]{sup 2+}. United States. doi:10.1021/jp9927754.
Damrauer, N H, and McCusker, J K. Thu . "Ultrafast dynamics in the metal-to-ligand charge transfer excited-state evolution of [Ru(4,4{prime}-diphenyl-2,2{prime}-bipyridine){sub 3}]{sup 2+}". United States. doi:10.1021/jp9927754.
@article{osti_20001109,
title = {Ultrafast dynamics in the metal-to-ligand charge transfer excited-state evolution of [Ru(4,4{prime}-diphenyl-2,2{prime}-bipyridine){sub 3}]{sup 2+}},
author = {Damrauer, N H and McCusker, J K},
abstractNote = {The transition metal complexes [Ru(dmb){sub 3}]{sup 2+}, where dmb is 4,4{prime}-dimethyl-2,2{prime}-bipyridine and dpb is 4,4{prime}-diphenyl-2,2{prime}-bipyridine, have been studied by femtosecond visible electronic absorption spectroscopy. Spectroelectrochemical measurements in conjunction with nanosecond time-resolved absorption spectroscopy allow for the assignment of various features in the excited-state differential absorption spectra as both ligand-based {pi}* {l{underscore}arrow} {pi}* and ligand-to-metal charge transfer (LMCT) in nature. A unique absorptive feature centered at {approximately} 530 nm in [Ru(dpb){sub 3}]{sup 2+} was identified as an optical marker for the thermalized (and hence fully intraligand delocalized) excited state. Single wavelength and full spectrum transient absorption data were obtained on both molecules in CH{sub 3}CN solution at room temperature following metal-to-ligand charge transfer (MLCT) excitation at 400 nm. Data on [Ru(dmb){sub 3}]{sup 2+} at 532 nm, a region of net excited-state absorption, revealed biphasic decay kinetics ({approximately}120 fs and 5 ps) attributed to a combination of {sup 1}MLCT {r{underscore}arrow} {sup 3}MLCT intersystem crossing and vibrational cooling dynamics. Dynamics for [Ru(dpb){sub 3}]{sup 2+} under identical conditions revealed biphasic rise times in the region of the ligand-based {pi}* {l{underscore}arrow} {pi}* absorption at {lambda}{sub probe} = 532 nm. Although the origin of the gas component ({approximately}200 fs) is not yet clear, the ca. 2 ps rise is assigned to rotation of the peripheral aryl ring and thus corresponds to the time scale for intraligand electron delocalization.},
doi = {10.1021/jp9927754},
journal = {Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory},
issn = {1089-5639},
number = 42,
volume = 103,
place = {United States},
year = {1999},
month = {10}
}