6005-15-8Relevant academic research and scientific papers
Photophysical triplet state processes of 4-H-1-benzopyrane-4-thione in a perfluoroalkane: Part 1. - Temperature dependence of unimolecular triplet decay
Eisenberger, Heike,Nickel, Bernhard
, p. 733 - 740 (1996)
The rate constant kTO for the unimolecular decay of the lowest triplet state, T1, of 4-H-1-benzopyrane-4-thione (BPT) in perfluoro1,3-dimethylcyclohexane was determined between 230 and 300 K. By assuming a very fast and virtually complete thermal equilibration T1 ? S1 of the relative population of T1 and the lowest excited singlet state S1, three parameters can be calculated from the temperature dependence of kTO: the individual rate constants βS = (4.0 ± 0.2) × 106 s-1 for the decay of S1 to S0 and βTz = (8.2 ± 2) × 104 s-1 for the decay of the strongly phosphorescent triplet substate T1z to S0, and the energy difference ΔE(S1,T1z) = hc × (757 ± 13) cm-1l between T1z and S1. The value of ΔE(S1,T1z) is in agreement with the positions of T1,0 and S1,0 in the absorption spectrum. The spectrum of the S0 → S1 transition is estimated. The assignment of the hot-band range of the delayed luminescence above the energy hcν0,0 of T1,0 is facilitated by an inverse Boltzmann weighting (multiplication with exp[hc(ν - ν0,0)/kBT]). At the position of S1,0, a contribution of E-type delayed S1 → S0 fluorescence can be discerned. The contribution of diffusion-controlled concentration-quenching (rate constant kQ) to the triplet decay was eliminated by extrapolation to infinite dilution; kQ is proportional to the ratio T/η of temperature T and viscosity η. The temperature dependence of the viscosity and density of perfluoro-1,3-dimethylcyclohexane were measured.
One-Pot Catalytic Cleavage of C=S Double Bonds by Pd Catalysts at Room Temperature
Zhu, Ting,Wu, Xiaoxi,Yang, Xinzheng,Sharma, Bigyan,Li, Na,Huang, Jiaming,Wang, Wentao,Xing, Wang,Zhao, Zhenwen,Huang, Hui
supporting information, p. 9266 - 9273 (2018/08/17)
The C=S double bonds in CS2 and thioketones were catalytically cleaved by Pd dimeric complexes [(N∧N)2Pd2(NO3)2](NO3)2 (N∧N, 2,2′-bipyridine, 4,4′-dimethylbipyridine or 4,4′-bis(trifluoromethyl)) at room temperature in one pot to afford CO2 and ketones, respectively, for the first time. The mechanisms were fully investigated by kinetic NMR, isotope-labeled experiments, in situ ESI-MS, and DFT calculations. The reaction is involved a hydrolytic desulfurization process to generate C=O double bonds and a trinuclear cluster, which plays a pivotal role in the catalytic cycle to regenerate the dimeric catalysts with HNO3. Furthermore, the electronic properties of catalyst ligands possess significant influence on reaction rates and kinetic parameters. At the same temperature, the reaction rate is consistent with the order of electronegativity of N∧N ligands (4,4′-bis(trifluoromethyl) > 2,2′-bipyridine > 4,4′-dimethylbipyridine). This homogeneous catalytic reaction features mild conditions, a broad substrate scope, and operational simplicity, affording insight into the mechanism of catalytic activation of carbon sulfur bonds.
α1-Adrenoceptor agonists: The identification of novel α1A subtype selective 2′-heteroaryl-2-(phenoxymethyl)imidazolines
Bishop, Michael J.,Barvian, Kevin A.,Berman, Judd,Bigham, Eric C.,Garrison, Deanna T.,Gobel, Michael J.,Hodson, Stephen J.,Irving, Paul E.,Liacos, James A.,Navas, Iii, Frank,Saussy Jr., David L.,Speake, Jason D.
, p. 471 - 475 (2007/10/03)
Novel 2′-heteroaryl-2-(phenoxymethyl)imidazolines have been identified as potent agonists of the cloned human α1-adrenoceptors in vitro. The nature of the 2′-heteroaryl group can have significant effects on the potency, efficacy, and subtype selectivity in this series. α1A Subtype selective agonists have been identified.
Microwave-accelerated solvent-free synthesis of thioketones, thiolactones, thioamides, thionoesters, and thioflavonoids
Varma, Rajender S.,Kumar, Dalip
, p. 697 - 700 (2008/02/11)
Formula presented An expeditious, solvent-free, and high yield conversion of ketones, flavones, isoflavones, lactones, amides, and esters to the corresponding thio analogues is described utilizing Lawesson's reagent in a process that circumvents the use of dry solvents and excess of the reagent.
Photosensitizers: Comprehensive Photophysics/Photochemistry and Theory of Coumarins, Chromones, their Homologues and Thione Analogues
Becker, Ralph S.,Chakravorti, Sankar,Gartner, Carlos A.,Miguel, Maria de Graca
, p. 1007 - 1020 (2007/10/02)
The photophysical-photochemical behaviour, including absorption spectra, flourescence spectra and lifetimes, phosphorescence spectra, triplet-triplet transient spectra, triplet lifetimes and quantum yields and sensitized singlet oxygen formation and yields, has been determined for many of a group of 22 carbonyl and thione compounds.These includes coumarins, psoralens, chromones and furochromone and their thiones.Many of the thiones were synthesized for the first time.Two types of theoretical calculations were carried out on the majority of the compounds.The principal goals of the research for the thiones, were (1) to produce or improve the photosensitizer capability of the compounds in vivo, (2) to shift the spectra of the compounds to significantly longer wavelength and (3) to increase the triplet and singlet oxygen quantum yields.Most of these have been largely achieved.The photosensitizing abilities of the two thiones have been evaluated using a unique testing technique employing a series of genitically engineered bacteria.
SOME NOVEL ASPECTS OF REGIOSELECTIVITY IN 1,3 DIPOLAR CYCLOADDITIONS OF 4H-1-BENZOPYRAN-4-THIONE
Baruah, Arpan K.,Prajapati, Dipak,Sandhu, Jagir S.
, p. 6137 - 6142 (2007/10/02)
4H-1-Benzopyran-4-thione (1) reacted smoothly with nitrilimines (3a-e) to afford regioselective cycloadducts (4a-e) in good yields.In contrast,benzonitrile oxide (6) and aldonitrones (7a-d) reacted preferentially at the thione function.The unstable cycloadduct (8) or (9) ruptured to give as isolable products chromone (10) and phenyl isothiocyanate (11) and the thioamides (12a-d).This indirectly proves the site of attack of the dipole at the thione group.
RELAXATION OF THE SECOND EXCITED SINGLET OF AROMATIC THIONES: THE ROLE OF SPECIFIC SOLUTE-SOLVENT INTERACTIONS
Maciejwski, A.,Demmer, D. R.,James, D. R.,Safarzadeh-Amiri, A.,Verrall, R. E.,Steer, R. P.
, p. 2831 - 2837 (2007/10/02)
Second excited singlet state (S2) fluorescence quantum yields and lifetimes of six aromatic thiones have been measured in solution at room temperature.Intermolecular S2->S1 internal conversion dominates S2 decay in inert perfluoroalkane solvents, but intermolecular photochemical and photophysical processes dominate in more strongly interacting solvents.Stern-volmer quenching is observed when perfluoroalkane solutions of 2,2,3,3-tetramethylindanathione, a model thione, are spiked with addens at contrentations up to ca. 0.3 M.Measurements of the rate constans for the biomolecular quenching of S2 fluorescence by 26 different addends reveal that the thione S2 state is highly reactive and that the initial intermolecular interaction path divides into physical and chemical branches, the branching ratio being a function of the nature of the quecher.
