The Metal-Metal-to-Ligand Charge Transfer Excited State and Supramolecular Polymerization of Luminescent Pincer PdII -Isocyanide Complexes

2018 ◽  
Vol 57 (12) ◽  
pp. 3089-3093 ◽  
Author(s):  
Qingyun Wan ◽  
Wai-Pong To ◽  
Chen Yang ◽  
Chi-Ming Che
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Ligand Charge Transfer ◽  
Metal Metal ◽  
Supramolecular Polymerization

Temperature dependence of photophysical properties of a dinuclear C^N-cyclometalated Pt(ii) complex with an intimate Pt–Pt contact. Zero-field splitting and sub-state decay rates of the lowest triplet

2018 ◽  
Vol 20 (38) ◽  
pp. 25096-25104 ◽  
Author(s):  
Joseph C. Deaton ◽  
Arnab Chakraborty ◽  
Rafal Czerwieniec ◽  
Hartmut Yersin ◽  
Felix N. Castellano
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Photophysical Properties ◽  
Decay Rates ◽  
Zero Field ◽  
Triplet Excited State ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Ligand Charge Transfer ◽  
Metal Metal

A dinuclear Pt(ii) complexes exhibits an unusually large zero field splitting in its metal–metal-to-ligand charge transfer triplet excited state.

Synthesis and Luminescence Properties of [Pt{4-(o-MeC6H4)- pzbipy}Cl]SbF6 [pzbipy = 6-2''-pyrazinyl)-2,22'-bipyridine]

2007 ◽  
Vol 62 (3) ◽  
pp. 447-452 ◽  
Author(s):  
John S. Field ◽  
Jan-André Gertenbach ◽  
Raymond J. Haines ◽  
Orde Q. Munro ◽  
David R. McMillin
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Variable Temperature ◽  
Emission Spectra ◽  
Fluid Solution ◽  
Orbital Interactions ◽  
Low Intensity ◽  
Ligand Charge Transfer ◽  
Metal Metal ◽  
Metal Ligand

The synthesis and characterisation of the 4-(o-R-C6H4)pzbipy [R = H, CH3 or CF3; pzbipy = 6-(2″- pyrazinyl)-2,2′-bipyridyl] ligands are described. Reaction of the 4-(o-MeC6H4)pzbipy ligand with [Pt(PhCN)2Cl2] in the presence of AgSbF6 affords [Pt{4-(o-MeC6H4)pzbipy}Cl]SbF6 as a marooncoloured microcrystalline solid. The [Pt{4-(o-MeC6H4)pzbipy}Cl]+ cation exhibits low intensity photoluminescence in dichloromethane that maximises at 543 nm and which is assigned to a 3MLCT excited state (τ = 20 ns). The emission spectrum of the cation was also recorded in a frozen DME {1 : 5:5 (v/v) DMF / MeOH / EtOH} glass; a highly structured band is observed with vibrational spacings of ca. 1400 cm−1, indicating emission from an intraligand 3π-π∗ state (τ = 11 μs). Variable temperature solid emission spectra show maxima that occur at significantly lower energies than is observed in fluid solution and that shift to the red when the temperature is lowered; specifically, λ (em)max is 674 nm at 280 K (τ = 80 ns) and 723 nm at 80 K (τ = 1.3 μs). Emission behaviour of this type is typical of emission from a metal-metal-ligand charge transfer (MMLCT) excited state that has its origins in dz² (Pt)-dz² (Pt) orbital interactions in the crystal.

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.

Ultrafast excited state dynamics of [Cr(CO)4(bpy)]: revealing the relaxation between triplet charge-transfer states

RSC Advances ◽  
2016 ◽  
Vol 6 (25) ◽  
pp. 20507-20515 ◽  
Author(s):  
Fei Ma ◽  
Martin Jarenmark ◽  
Svante Hedström ◽  
Petter Persson ◽  
Ebbe Nordlander ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Absorption Spectroscopy ◽  
Dft Calculation ◽  
Pump Probe ◽  
Excited State Dynamics ◽  
Mlct Transition ◽  
Ligand Charge Transfer ◽  
Probe Absorption

Ultrafast excited state dynamics of [Cr(CO)4(bpy)] upon metal-to-ligand charge-transfer (1MLCT) transition have been studied by pump-probe absorption spectroscopy and DFT calculation.

scholarly journals Sensitization of ultra-long-range excited-state electron transfer by energy transfer in a polymerized film

2012 ◽  
Vol 109 (38) ◽  
pp. 15132-15135 ◽  
Author(s):  
Akitaka Ito ◽  
David J. Stewart ◽  
Zhen Fang ◽  
M. Kyle Brennaman ◽  
Thomas J. Meyer
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Excited State ◽  
Charge Transfer ◽  
Long Range ◽  
Methyl Viologen ◽  
Polymer Network ◽  
Triplet Energy ◽  
Ligand Charge Transfer ◽  
Triplet Energy Transfer

Distance-dependent energy transfer occurs from the Metal-to-Ligand Charge Transfer (MLCT) excited state to an anthracene-acrylate derivative (Acr-An) incorporated into the polymer network of a semirigid poly(ethyleneglycol)dimethacrylate monolith. Following excitation, to Acr-An triplet energy transfer occurs followed by long-range, Acr-3An—Acr-An → Acr-An—Acr-3An, energy migration. With methyl viologen dication (MV2+) added as a trap, Acr-3An + MV2+ → Acr-An+ + MV+ electron transfer results in sensitized electron transfer quenching over a distance of approximately 90 Å.

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