Excited-State Engineering of Oligothiophenes via Phosphorus Chemistry towards Strong Fluorescent Materials

2021 ◽  
Author(s):  
Zi Yang ◽  
Zhikai Zhang ◽  
CeCe Xue ◽  
Kai Yang ◽  
Rong Gao ◽  
...  
Keyword(s):  
Excited State ◽  
Intersystem Crossing ◽  
Triplet Excited State ◽  
Radiative Processes ◽  
Fluorescent Materials ◽  
Phosphorus Chemistry

Due to the efficient intersystem crossing (ISC), combined with efficient non-radiative processes of the triplet excited state, oligothiophenes generally exhibit very weak photoluminescence. Phosphorus (P)-bridged terthiophenes (P-terThs) and phosphorus (P)-bridged...

The mechanism of the photochemical cycloaddition reaction of N-benzoylindole with cyclopentene

1990 ◽  
Vol 68 (10) ◽  
pp. 1685-1692 ◽  
Author(s):  
Bimsara W. Disanayaka ◽  
Alan C. Weedon
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Ground State ◽  
Mechanistic Model ◽  
Cycloaddition Reaction ◽  
Intersystem Crossing ◽  
Triplet Excited State ◽  
Excited State Lifetime ◽  
Yield Data ◽  
Counting Procedure

The mechanism of the photochemical cycloaddition reaction between N-benzoylindole, 1, and cyclopentene to give cyclobutane adducts 2 and 3 has been examined. The triplet excited state lifetime and quantum yield of intersystem crossing were determined for 1 as (2.8 ± 0.3) × 10−8 s and 0.39 ± 0.01, respectively, using the triplet counting procedure. In addition, the dependence of the quantum yield of cycloadduct formation upon the concentration of cyclopentene and upon the concentration of excited state quenchers has been determined. The results are used to propose a mechanistic model in which the triplet excited state of 1 reacts with cyclopentene to give a triplet 1,4-biradical intermediate. Following spin inversion the biradical intermediate reverts to the ground state starting materials or proceeds to the products 2 and 3; this partitioning, along with the quantum yield of intersystem crossing, gives rise to a limiting quantum yield of cycloaddition at infinite alkene concentration of 0.061. It is calculated that 84% of the biradical intermediates revert to the starting materials and 16% proceed to cycloadducts. The quantum yield data are also used to calculate two independent values of the rate constant for reaction of the triplet excited 1 with alkene; the values are (1.8 ± 0.1) × 107M−1 s−1 and (4.0 ± 0.8) × 106 M−1 s−1'. Some evidence for self quenching of the triplet excited state of 1 by ground state 1 was also observed. The quantum yield of intersystem crossing and the triplet excited state lifetime of 1 were found to vary with the solvent used; this is discussed in terms of the possible existence of a charge transfer triplet excited state. Keywords: indole, photocycloaddition, mechanism.

Efficient intersystem crossing using singly halogenated carbomethoxyphenyl porphyrins measured using delayed fluorescence, chemical quenching, and singlet oxygen emission

2015 ◽  
Vol 17 (43) ◽  
pp. 29090-29096 ◽  
Author(s):  
Dawn M. Marin ◽  
Sonia Payerpaj ◽  
Graham S. Collier ◽  
Angy L. Ortiz ◽  
Gaurav Singh ◽  
...  
Keyword(s):  
Excited State ◽  
Singlet Oxygen ◽  
State Formation ◽  
Delayed Fluorescence ◽  
Intersystem Crossing ◽  
Fluorescence Lifetimes ◽  
Triplet Excited State

Singly halogenated carbomethoxyphenylporphyrins show decreased singlet fluorescence lifetimes and increased rates of triplet excited state formation.

scholarly journals Triplet excited state properties in variable gap π-conjugated donor–acceptor–donor chromophores

2016 ◽  
Vol 7 (6) ◽  
pp. 3621-3631 ◽  
Author(s):  
Seda Cekli ◽  
Russell W. Winkel ◽  
Erkki Alarousu ◽  
Omar F. Mohammed ◽  
Kirk S. Schanze
Keyword(s):  
Excited State ◽  
Intersystem Crossing ◽  
Triplet Excited State ◽  
Acceptor Interaction ◽  
Donor Acceptor

Intersystem crossing in π-conjugated donor–acceptor–donor chromophores is controlled by the strength of the donor–acceptor interaction.

Photolysis of polychlorinated benzenes in cyclohexane solution

1983 ◽  
Vol 61 (6) ◽  
pp. 1103-1104 ◽  
Author(s):  
Nigel J. Bunce ◽  
Patrick J. Hayes ◽  
Mary E. Lemke
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Concentration Dependence ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Triplet Excited State ◽  
Chlorinated Benzenes ◽  
Polychlorinated Benzenes

Quantum yields of dechlorination and of intersystem crossing have been measured in cyclohexane for a series of chlorinated benzenes. The results are compatible with the reactions occurring predominantly from the triplet excited state. The quantum yield of reaction shows a concentration dependence on [Formula: see text], but the dependence is less for the more heavily chlorinated members of the scries.

Spin–orbit charge transfer intersystem crossing in perylenemonoimide–phenothiazine compact electron donor–acceptor dyads

2018 ◽  
Vol 54 (87) ◽  
pp. 12329-12332 ◽  
Author(s):  
Yingjie Zhao ◽  
Ruomeng Duan ◽  
Jianzhang Zhao ◽  
Chen Li
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Electron Donor ◽  
Intersystem Crossing ◽  
Spin Orbit ◽  
Triplet Excited State ◽  
Donor Acceptor ◽  
State Production

Efficient triplet excited state production (57%) was observed for perylenemonoimide–phenothiazine compact electron donor–acceptor dyads based on spin–orbit charge transfer ISC.

scholarly journals Tuning the singlet-triplet energy gap: a unique approach to efficient photosensitizers with aggregation-induced emission (AIE) characteristics

2015 ◽  
Vol 6 (10) ◽  
pp. 5824-5830 ◽  
Author(s):  
Shidang Xu ◽  
Youyong Yuan ◽  
Xiaolei Cai ◽  
Chong-Jing Zhang ◽  
Fang Hu ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Energy Gap ◽  
Intersystem Crossing ◽  
Triplet Excited State ◽  
Triplet Energy ◽  
Aggregation Induced Emission ◽  
Unique Approach ◽  
Triplet Excited States

The efficiency of the intersystem crossing process can be improved by reducing the energy gap between the singlet and triplet excited states (ΔEST), which offers the opportunity to improve the yield of the triplet excited state.

Intersystem crossing and triplet excited state properties of thionated naphthalenediimide derivatives

2017 ◽  
Vol 192 ◽  
pp. 211-217 ◽  
Author(s):  
Mushraf Hussain ◽  
Jianzhang Zhao ◽  
Wenbo Yang ◽  
Fangfang Zhong ◽  
Ahmet Karatay ◽  
...  
Keyword(s):  
Excited State ◽  
Intersystem Crossing ◽  
Triplet Excited State
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