Cucurbituril Complexation Enhances Intersystem Crossing and Triplet Lifetime of 2,4,6-Triphenylpyrylium Ion

2010 ◽  
Vol 114 (5) ◽  
pp. 2034-2038 ◽  
Author(s):  
Pedro Montes-Navajas ◽  
Hermenegildo Garcia
Keyword(s):  
Intersystem Crossing ◽  
Triplet Lifetime

Photochemistry of cyclododecanone

1976 ◽  
Vol 29 (11) ◽  
pp. 2477 ◽  
Author(s):  
PJ Burchill ◽  
AG Kelso ◽  
AJ Power
Keyword(s):  
Cleavage Product ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Quantitative Measurements ◽  
Acyclic Ketones ◽  
Triplet Lifetime

Quantitative measurements of the photolytic reactions of cyclododecanone gave quantum yields of reaction and of intersystem crossing as 0.56 and 0.88 respectively, and a triplet lifetime of 1.7 x 10-7 s. Cyclobutanol formation accounts for most of the reaction with only a low yield of the Norrish II cleavage product; this contrasts markedly with the opposite behaviour of acyclic ketones of similar size. The results may be explained by the apparent restriction of rotation in cyclododecanone molecules.

Photocyanation of 3,4-dimethoxy-1-nitrobenzene. A quantitative study

1986 ◽  
Vol 51 (2) ◽  
pp. 358-367 ◽  
Author(s):  
Petr Kuzmič ◽  
Milan Souček
Keyword(s):  
Quantum Yield ◽  
Quantitative Study ◽  
Rate Constant ◽  
Potassium Cyanide ◽  
Intersystem Crossing ◽  
Excited Triplet ◽  
Cyanide Anion ◽  
Tert Butanol ◽  
Diffusion Controlled ◽  
Triplet Lifetime

UV photolysis (365 nm) of 3,4-dimethoxy-1-nitrobenzene in the presence of potassium cyanide leading to 3-cyano-4-methoxy-1-nitrobenzene was subjected to a quantitative photokinetic study. The reaction exhibits a second order kinetics with respect to the nucleophile and is effectively quenched by molecular oxygen as well as 2,4-hexadienoic acid. The excited triplet lifetime of 0.9 microseconds was determined on the basis of the dependence of quantum yield on the nucleophile and quencher concentrations in 50% aqueous tert-butanol. The quantum yield of intersystem crossing is at least 0.38 in the same solvent; bimolecular rate constant for the interaction of triplet 3,4-dimethoxy-1-nitrobenzene with cyanide anion has the value of 5.6 . 108 l . mol-1s-1, which is approximately one half of the rate constant for diffusion controlled quenching. Quantum yield of the reaction is strongly dependent on the water content in mixtures with tert-butanol and increases from 0.04 in water to 0.68 in 88% tert-butanol.

Ground and Excited State Dynamics of Core-modified Normal and Expanded Porphyrins

1998 ◽  
Vol 02 (04) ◽  
pp. 305-314 ◽  
Author(s):  
A. SRINIVASAN ◽  
M. RAVI KUMAR ◽  
R. P. PANDIAN ◽  
S. MAHAJAN ◽  
K. SIMI PUSHPAN ◽  
...  
Keyword(s):  
Excited State ◽  
Binding Constants ◽  
Spectral Studies ◽  
Intersystem Crossing ◽  
Triplet Excited State ◽  
Absorption Bands ◽  
Fluoride Ions ◽  
Expanded Porphyrins ◽  
Derivatives Of ◽  
Triplet Lifetime

Singlet and triplet excited state data on two new core-modified expanded porphyrins and their protonated derivatives are reported. Absorption spectral studies indicate a gradual red shift of the absorption bands upon sulfur substitution into the core. The singlet lifetimes for expanded S 3-sapphyrin and S 4-rubyrin decrease steadily relative to STPPH and S 2 TPP owing to a higher rate of intersystem crossing. Furthermore, the protonated derivatives of S 3-sapphyrin and S 4-rubyrin encapsulate fluoride ions into their cavities with binding constants of 807 and 48 M−1 respectively. However, the triplet lifetime for S 3-sapphyrin is longer (58.80 μs) than for normal thiaporphyrins (STPPH, 37.45 μs; S 2 TPP , 20.96 μs), suggesting that it could be very well suited for photosensitizing triplet oxygen.

Spin-Forbidden Excitation Enables Infrared Photoredox Catalysis

2020 ◽  
Author(s):  
Tomislav Rovis ◽  
Benjamin D. Ravetz ◽  
Nicholas E. S. Tay ◽  
Candice Joe ◽  
Melda Sezen-Edmonds ◽  
...  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Intersystem Crossing ◽  
Photoredox Catalysis ◽  
Infrared Irradiation ◽  
Triplet Excitation ◽  
New Family ◽  
Ir Light

We describe a new family of catalysts that undergo direct ground state singlet to excited state triplet excitation with IR light, leading to photoredox catalysis without the energy waste associated with intersystem crossing. The finding allows a mole scale reaction in batch using infrared irradiation.

scholarly journals Intersystem crossing processes in the 2CzPN emitter: a DFT/MRCI study including vibrational spin–orbit interactions

2021 ◽  
Vol 23 (5) ◽  
pp. 3668-3678
Author(s):  
Angela Rodriguez-Serrano ◽  
Fabian Dinkelbach ◽  
Christel M. Marian
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Intersystem Crossing ◽  
Spin Orbit ◽  
Spin Orbit Interactions

Multireference quantum chemical calculations were performed in order to investigate the (reverse) intersystem crossing ((R)ISC) mechanisms of 4,5-di(9H-carbazol-9-yl)-phthalonitrile (2CzPN).

Electron transfer sensitized photolysis of 'onium salts

1988 ◽  
Vol 66 (2) ◽  
pp. 319-324 ◽  
Author(s):  
R. J. DeVoe ◽  
M. R. V. Sahyun ◽  
Einhard Schmidt ◽  
N. Serpone ◽  
D. K. Sharma
Keyword(s):  
Electron Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Quantitative Model ◽  
Intersystem Crossing ◽  
Single Electron Transfer ◽  
Onium Salts ◽  
Encounter Complex ◽  
Back Electron Transfer

We have studied the anthracene-sensitized photolyses of both diphenyliodonium and triphenylsulphonium salts in solution using both steady-state and laser flash photolysis techniques. Photoproducts, namely, phenylated anthracenes along with iodobenzene or diphenylsulphide, respectively, are obtained from both salts with quantum efficiencies of ca. 0.1 at 375 nm. We infer the intermediacy of diphenyliodo and triphenylsulphur radicals formed by single electron transfer from the singlet-excited anthracene. We have developed a quantitative model of this chemistry, and identify the principal sources of inefficiency as back electron transfer, which occurs at nearly the theoretically limiting rate, intersystem crossing from the initially formed sensitizer–'onium salt encounter complex, and in-cage radical recombination.

Why Triage the Materials with Low Luminescence Quantum Efficiency: The Use of 35Cbz4BzCN as a Universal Host for Organic Light Emitting Diode through Effective Triplet Energy Transfer

2021 ◽  
Author(s):  
Yi-Mei Huang ◽  
Tse-Ying Chen ◽  
Deng-Gao Chen ◽  
Hsuan-Chi Liang ◽  
Cheng-Ham Wu ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Delayed Fluorescence ◽  
Triplet Energy ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Thermally Activated ◽  
Triplet Energy Transfer ◽  
Triplet Lifetime ◽  
Triplet Excitons

35Cbz4BzCN, a novel universal host with long triplet lifetime, has been developed. The triplet excitons in 35Cbz4BzCN can be effectively harvested by phosphorescence and thermally activated delayed fluorescence emitters. In...

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