Geometry, electronic structure, and coordination ability of (diiminoethane)bis(phosphine)copper(1+) at the lowest energy triplet metal-to-ligand charge-transfer excited state. A theoretical study

1992 ◽  
Vol 31 (22) ◽  
pp. 4575-4581 ◽  
Author(s):  
Shigeyoshi Sakaki ◽  
Hiroki Mizutani ◽  
Yuichi Kase
Keyword(s):  
Electronic Structure ◽  
Excited State ◽  
Charge Transfer ◽  
Theoretical Study ◽  
Ligand Charge Transfer ◽  
Coordination Ability

scholarly journals Multireference Description of Nickel–Aryl Homolytic Bond Dissociation Processes in Photoredox Catalysis

2020 ◽  
Author(s):  
David Cagan ◽  
Gautam Stroscio ◽  
Alexander Cusumano ◽  
Ryan Hadt
Keyword(s):  
Electronic Structure ◽  
Excited State ◽  
Charge Transfer ◽  
Density Functional ◽  
Single Photon ◽  
Ligand Field ◽  
Initial Population ◽  
Bond Dissociation ◽  
Ligand Charge Transfer ◽  
Triplet Excited States

<p>Multireference electronic structure calculations consistent with known experimental data have elucidated a novel mechanism for photo-triggered Ni(II)–C homolytic bond dissociation in Ni 2,2’-bipyridine (bpy) photoredox catalysts. Previously, a thermally assisted dissociation from the lowest energy triplet ligand field excited state was proposed and supported by density functional theory (DFT) calculations that reveal a barrier of ~30 kcal mol<sup>-1</sup>. In contrast, multireference ab initio calculations suggest this process is disfavored, with barrier heights of ~70 kcal mol<sup>-1</sup>, and highlight important ligand noninnocent contributions to excited state relaxation and bond dissociation processes that are not captured with DFT. In the multireference description, photo-triggered Ni(II)–C homolytic bond dissociation occurs via initial population of a singlet Ni(II)-to-bpy metal-to-ligand charge transfer (<sup>1</sup>MLCT) excited state followed by intersystem crossing and aryl-to-Ni(III) charge transfer, overall a formal two-electron transfer process driven by a single photon. This results in repulsive triplet excited states from which spontaneous homolytic bond dissociation can occur, effectively competing with relaxation to the lowest energy, nondissociative triplet Ni(II) ligand field excited state. These findings guide important electronic structure considerations for the experimental and computational elucidation of the mechanisms of ground and excited state cross-coupling catalysis mediated by Ni heteroaromatic complexes.</p>

scholarly journals Multireference Description of Nickel–Aryl Homolytic Bond Dissociation Processes in Photoredox Catalysis

2020 ◽  
Author(s):  
David Cagan ◽  
Gautam Stroscio ◽  
Alexander Cusumano ◽  
Ryan Hadt
Keyword(s):  
Electronic Structure ◽  
Excited State ◽  
Charge Transfer ◽  
Density Functional ◽  
Single Photon ◽  
Ligand Field ◽  
Initial Population ◽  
Bond Dissociation ◽  
Ligand Charge Transfer ◽  
Triplet Excited States

<p>Multireference electronic structure calculations consistent with known experimental data have elucidated a novel mechanism for photo-triggered Ni(II)–C homolytic bond dissociation in Ni 2,2’-bipyridine (bpy) photoredox catalysts. Previously, a thermally assisted dissociation from the lowest energy triplet ligand field excited state was proposed and supported by density functional theory (DFT) calculations that reveal a barrier of ~30 kcal mol<sup>-1</sup>. In contrast, multireference ab initio calculations suggest this process is disfavored, with barrier heights of ~70 kcal mol<sup>-1</sup>, and highlight important ligand noninnocent contributions to excited state relaxation and bond dissociation processes that are not captured with DFT. In the multireference description, photo-triggered Ni(II)–C homolytic bond dissociation occurs via initial population of a singlet Ni(II)-to-bpy metal-to-ligand charge transfer (<sup>1</sup>MLCT) excited state followed by intersystem crossing and aryl-to-Ni(III) charge transfer, overall a formal two-electron transfer process driven by a single photon. This results in repulsive triplet excited states from which spontaneous homolytic bond dissociation can occur, effectively competing with relaxation to the lowest energy, nondissociative triplet Ni(II) ligand field excited state. These findings guide important electronic structure considerations for the experimental and computational elucidation of the mechanisms of ground and excited state cross-coupling catalysis mediated by Ni heteroaromatic complexes.</p>

scholarly journals Exploring the Franck-Condon region of a photoexcited charge transfer complex in solution to interpret femtosecond stimulated Raman spectroscopy: excited state electronic structure methods to unveil non-radiative pathways

2021 ◽  
Author(s):  
Federico Coppola ◽  
Paola Cimino ◽  
Umberto Raucci ◽  
Maria Gabriella Chiariello ◽  
Alessio Petrone ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Electronic Structure ◽  
Excited State ◽  
Charge Transfer ◽  
Charge Transfer Complex ◽  
Main Role ◽  
Photoinduced Charge Transfer ◽  
Electronic Structure Methods ◽  
Franck Condon ◽  
Photoinduced Charge

We present electronic structure methods to unveil non-radiative pathways of photoinduced charge transfer (CT) reactions that play a main role in photophysics and light harvesting technologies. A prototypical π-stacked molecular...

Theoretical study on excited state structures and charge transfer characteristics of 2,2′-bipyridine

2003 ◽  
Vol 137 (1-3) ◽  
pp. 1095-1096 ◽  
Author(s):  
Z.M. Su ◽  
Y.H. Kan ◽  
Z.H. Huang ◽  
Y. Liao ◽  
Y.Q. Qiu ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Theoretical Study ◽  
Transfer Characteristics

scholarly journals Ingenious modification of molecular structure effectively regulates excited-state intramolecular proton and charge transfer: a theoretical study based on 3-hydroxyflavone

RSC Advances ◽  
2018 ◽  
Vol 8 (52) ◽  
pp. 29589-29597 ◽  
Author(s):  
Jianhui Han ◽  
Xiaochun Liu ◽  
Chaofan Sun ◽  
You Li ◽  
Hang Yin ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Excited State ◽  
Charge Transfer ◽  
Proton Transfer ◽  
Theoretical Study ◽  
Intramolecular Charge Transfer ◽  
Intramolecular Proton Transfer ◽  
Great Promise ◽  
Fluorescence Sensing

Harnessing ingenious modification of molecular structure to regulate excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) characteristics holds great promise in fluorescence sensing and imaging.

A density functional theory and spectroscopic study of intramolecular quenching of metal-to-ligand charge-transfer excited states in some mono-bipyridine ruthenium(II) complexes

2014 ◽  
Vol 92 (10) ◽  
pp. 996-1009 ◽  
Author(s):  
Shivnath Mazumder ◽  
Ryan A. Thomas ◽  
Richard L. Lord ◽  
H. Bernhard Schlegel ◽  
John F. Endicott
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Lower Energy ◽  
Density Functional ◽  
Dimethyl Sulfide ◽  
Intramolecular Electron Transfer ◽  
Functional Theory ◽  
Ligand Charge Transfer

The complexes [Ru(NCCH3)4bpy]2+ and [Ru([14]aneS4)bpy]2+ ([14]aneS4 = 1,4,8,11-tetrathiacyclotetradecane, bpy = 2,2′-bipyridine) have similar absorption and emission spectra but the 77 K metal-to-ligand charge-transfer (MLCT) excited state emission lifetime of the latter is less than 0.3% that of the former. Density functional theory modeling of the lowest energy triplet excited states indicates that triplet metal centered (3MC) excited states are about 3500 cm−1 lower in energy than their 3MLCT excited states in both complexes. The differences in excited state lifetimes arise from a much larger coordination sphere distortion for [Ru(NCCH3)4bpy]2+ and the associated larger reorganizational barrier for intramolecular electron transfer. The smaller ruthenium ligand distortions of the [Ru([14]aneS4)bpy]2+ complex are apparently a consequence of stereochemical constraints imposed by the macrocyclic [14]aneS4 ligand, and the 3MC excited state calculated for the unconstrained [Ru(S(CH3)2)4bpy]2+ complex (S(CH3)2 = dimethyl sulfide) is distorted in a manner similar to that of [Ru(NCCH3)4bpy]2+. Despite the lower energy calculated for its 3MC than 3MLCT excited state, [Ru(NCCH3)4bpy]2+ emits strongly in 77 K glasses with an emission quantum yield of 0.47. The emission is biphasic with about a 1 μs lifetime for its dominant (86%) emission component. The 405 nm excitation used in these studies results in a significant amount of photodecomposition in the 77 K glasses. This is a temperature-dependent biphotonic process that most likely involves the bipyridine-radical anionic moiety of the 3MLCT excited state. A smaller than expected value found for the radiative rate constant is consistent with a lower energy 3MC than 3MLCT state.

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