Theoretical Studies on the Electronic Structures and Spectral Properties of Two Iridium(III) Complexes with Tetraphenylimidodiphosphinate Ligand

2013 ◽  
Vol 660 ◽  
pp. 35-39
Author(s):  
De Ming Han ◽  
Gang Zhang ◽  
Li Hui Zhao
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Spectral Properties ◽  
Emission Spectra ◽  
Electron Affinities ◽  
Geometrical Structures ◽  
Ligand Charge Transfer ◽  
Triplet Excited States ◽  
Homo Lumo ◽  
Theoretical Results

The geometrical structures, electronic structures, and spectral properties of two Ir(III) complexes with tetraphenylimidodiphosphinate ligand were investigated theoretically. The ground and the lowest lying triplet excited states were fully optimized at the B3LYP/LANL2DZ. TDDFT/PCM calculations have been employed to predict the absorption and emission spectra starting from the ground and excited state geometries, respectively. The lowest lying absorptions were calculated to be at 436 and 405 nm for the two Ir(III) complexes, respectively, and they have the transition configuration of HOMO → LUMO. The lowest lying transitions can be assigned as metal/ligand-to-ligand charge transfer (MLCT/LLCT) character for the two Ir(III) complexes. Ionization potentials (IP) and electron affinities (EA) were calculated to evaluate the injection abilities of holes and electrons. The theoretical results can be expected to provide valuable information to design new OLED materials.

Spectroscopic trends in a series of Re(I) α-diimine complexes as a function of the antenna/photoisomerizable ligands: a TD-DFT and MS-CASPT2 study

2014 ◽  
Vol 92 (10) ◽  
pp. 979-986 ◽  
Author(s):  
Megumi Kayanuma ◽  
Chantal Daniel ◽  
Etienne Gindensperger
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Density Functional ◽  
Time Dependent ◽  
Functional Theory ◽  
B3lyp Level ◽  
Ligand Charge Transfer ◽  
Td Dft ◽  
Energy Domain ◽  
Diimine Complexes

The absorption spectra of 11 rhenium(I) complexes with photoisomerizable stilbene-like ligands have been investigated by means of density functional theory (DFT). The electronic structures of the ground and excited states were determined for [Re(CO)3(N,N)(L)]+ (N,N = bpy (2,2′-bipyridine), phen (1,10-phenanthroline), Me4phen (3,4,7,8-tetramethyl-1,10-phenanthroline), ph2phen (4,7-diphenyl-1,10-phenanthroline), or Clphen (5-chloro-1,10-phenanthroline); L = bpe (1,2-bis(4-pyrydil)ethylene), stpy (4-styrylpyridine), or CNstpy (4-(4-cyano)styrylpyridine)) at the time–dependent (TD) DFT/CAM-B3LYP level of theory in vacuum and acetonitrile to highlight the effects of both antenna N,N and isomerizable L ligands. The TD-DFT spectra of two representative complexes, namely [Re(CO)3(bpy)(stpy)]+ and [Re(CO)3(phen)(bpe)]+, have been compared with MS-CASPT2 spectra. The TD-DFT spectra obtained in vacuum and acetonitrile agree rather well both with the ab initio and experimental spectra. The absorption spectroscopy of this series of molecules is characterized by the presence of three low-lying metal to ligand charge transfer (MLCT) states absorbing in the visible energy domain. The nature of the isomerizable ligands (bpe, stpy, or CNstpy) and the type of antenna ligands (bpy, phen, and substituted phen) control the degree of mixing between the MLCT and intraligand excited states, their relative energies, as well as their intensities.

Access to the triplet excited states of organic chromophores

2020 ◽  
Vol 49 (17) ◽  
pp. 6122-6140 ◽  
Author(s):  
Devika Sasikumar ◽  
Athira T. John ◽  
Jeswin Sunny ◽  
Mahesh Hariharan
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Organic Chromophores ◽  
Triplet Excited States

Triplet excited states, ubiquitous in organic chromophores, can be accessed through various pathways. The feasibility of each pathway is determined by the molecular and electronic structures of the organic chromophores.

scholarly journals Resolving Electron Injection from Singlet Fission-Borne Triplets into Mesoporous Transparent Conducting Oxides

2021 ◽  
Author(s):  
Melissa Gish ◽  
John E. Anthony ◽  
Nathan R. Neale ◽  
Karl J. Thorley ◽  
Justin C. Johnson ◽  
...  
Keyword(s):  
Excited States ◽  
Organic Dyes ◽  
Transparent Conducting Oxides ◽  
Singlet Fission ◽  
Conducting Oxides ◽  
Transparent Conducting ◽  
Ligand Charge Transfer ◽  
Oxide Substrates ◽  
Mesoporous Oxide ◽  
Triplet Excited States

Photoinduced electron transfer into mesoporous oxide substrates is well-known to occur efficiently for both singlet and triplet excited states in conventional metal-to-ligand charge transfer (MLCT) dyes. However, in all-organic dyes...

scholarly journals The Effect of N-Heterocyclic Carbene Units on the Absorption Spectra of Fe(II) Complexes: A Challenge for Theory

2020 ◽  
Author(s):  
Olga S. Bokareva ◽  
Omar Baig ◽  
Mohamed Al-Marri ◽  
Oliver Kühn ◽  
Leticia Gonzalez
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Excited States ◽  
Partial Charge Transfer ◽  
Polypyridyl Ligands ◽  
Electronic Excited States ◽  
Heteroleptic Complexes ◽  
Ligand Charge Transfer ◽  
Exact Exchange ◽  
Triplet Excited States

<div>The absorption spectra of five Fe(II) homoleptic and heteroleptic complexes containing strong sigma-donating N-heterocyclic carbene (NHC) and polypyridyl ligands have been theoretically characterized using a tuned range-separation functional.</div><div>From a benchmark comparison of the obtained results against other functionals and a multiconfigurational reference, it is concluded that none of the methods is completely satisfactory to describe the absorption spectra.</div><div>Using a compromised choice of 20\% exact exchange, the electronic excited states underlying the absorption spectra are analyzed.</div><div>The low-lying energy band of all the compounds shows predominant metal-to-ligand charge transfer (MLCT) character while the triplet excited states have metal-centered (MC) nature, which becomes more pronounced with increasing the number of NHC-donor groups. Excited MC states with partial charge transfer to the NHC-donor groups are higher in energy than comparable states without these contributions. The presence of the low-lying MC states prevents the formation of long-lived MLCT states.</div>

scholarly journals The Effect of N-Heterocyclic Carbene Units on the Absorption Spectra of Fe(II) Complexes: A Challenge for Theory

2020 ◽  
Author(s):  
Olga S. Bokareva ◽  
Omar Baig ◽  
Mohamed Al-Marri ◽  
Oliver Kühn ◽  
Leticia Gonzalez
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Excited States ◽  
Partial Charge Transfer ◽  
Polypyridyl Ligands ◽  
Electronic Excited States ◽  
Heteroleptic Complexes ◽  
Ligand Charge Transfer ◽  
Exact Exchange ◽  
Triplet Excited States

<div>The absorption spectra of five Fe(II) homoleptic and heteroleptic complexes containing strong sigma-donating N-heterocyclic carbene (NHC) and polypyridyl ligands have been theoretically characterized using a tuned range-separation functional.</div><div>From a benchmark comparison of the obtained results against other functionals and a multiconfigurational reference, it is concluded that none of the methods is completely satisfactory to describe the absorption spectra.</div><div>Using a compromised choice of 20\% exact exchange, the electronic excited states underlying the absorption spectra are analyzed.</div><div>The low-lying energy band of all the compounds shows predominant metal-to-ligand charge transfer (MLCT) character while the triplet excited states have metal-centered (MC) nature, which becomes more pronounced with increasing the number of NHC-donor groups. Excited MC states with partial charge transfer to the NHC-donor groups are higher in energy than comparable states without these contributions. The presence of the low-lying MC states prevents the formation of long-lived MLCT states.</div>

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