492-21-7Relevant articles and documents
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 (1985)
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.
Generation of “Sumanenylidene”: A Ground-State Triplet Carbene on a Curved π-Conjugated Periphery
Yakiyama, Yumi,Wang, Yufeng,Hatano, Sayaka,Abe, Manabu,Sakurai, Hidehiro
, p. 1844 - 1848 (2019)
We have observed the generation of sumanenylidene (2), a divalent, neutral-carbon species at the benzylic position of sumanene (1). We also clarified both experimentally and theoretically that the ground state of compound 2 was a triplet state and that its singlet–triplet energy gap (ΔEST) was similar to that in fluorenylidene. The curved structure of compound 2 led to slightly better spin delocalization over the two adjacent aromatic rings than in planar systems, because of the unpaired spins on the σ and π orbitals. Synthetic application of the carbene precursor, diazosumanene (5), with a variety of thiocarbonyl compounds revealed its utility for the preparation of tetrasubstituted alkene compounds (e.g., that contain a strongly electron-donating unit) that are directly conjugated to the sumanene (1) moiety.
Variations of bistricyclic aromatic enes: Mono-bridged tetraarylethene naphthologs
Assadi, Naela,Pogodin, Sergey,Cohen, Shmuel,Agranat, Israel
, p. 319 - 352 (2015)
The syntheses, molecular and crystal structures, NMR spectroscopic study, and DFT computational study of naphthologs of mono-bridged (X = -, O, S, Se, and Te) tetraarylethene (BAE-1s) 11-25 with α,α-, β,β-, and α,β-dinaphthalenyl substituents have been reported. The BAE-1s have been prepared by Barton-Kellog twofold extrusion from the respective chalcogenothiones and diazomethylenebisnaphthylenes. Complete assignments of 1H- and 13C-NMR spectra of 11-25 have been made through 2-dimensional correlation spectroscopy (DQF-COSY, HSQC, HMBC, and NOESY). The corresponding intermediates, thiiranes 33-47, have been also isolated (except 38), and their molecular and crystal structures have been determined. The molecular structures of BAE-1s 12-15, 20, and 22-25 adopted folded-twisted conformations with considerably folded (φ = 30°-57°) tricyclic moieties. The α,α- and α,β-dinaphthalenyl derivatives are more overcrowded than β,β-dinaphthalenyl derivatives. The relief of the steric strain due to the overcrowding around C9 = C9' caused by the presence of naphthalenyl substituents was achieved by their twisting around the single bonds that connect the α-naphthalenyl and β-naphthalenyl moieties to C9'. The 1H-NMR spectra have shown shielding of H2, H7 of 11-25 and the pronounced deshielding of H8', H8′ of α,α-dinaphthalenyl-substituted BAE-1s 13-15 in contrast to β,β-dinaphthalenyl-substituted BAE-1s 16-20. The upfield shifts of H2, H7 suggested conformations in which these hydrogens are located above the planes of the opposing naphthalene rings. DFT calculations of 11-20 have been performed at B3LYP/6-31G(d) and B3LYP/SDD. The results have shown that the global minima of BAE-1s without a chalcogen bridge 11 and 16 are twisted (-sc,-sc)-C 2-t conformations. The global minima of BAE-1s with a chalcogen bridge are folded-twisted (-sc,-ac)-C 1-ft conformations for α,α-dinaphthalenyl-substituted BAE-1s 12-15 and either anti- or syn-(-sc,ac)-C 1-ft conformations for β,β-dinaphthalenyl-substituted BAE-1s 17-20. The pronounced differences between the α,α-dinaphthalenyl and the β,β-dinaphthalenyl derivatives are noted. Dispersion-corrected B3LYP calculations stabilize significantly the α,α-dinaphthalenyl derivatives versus the β,β-dinaphthalenyl derivatives. The geometrical parameters of BAEs-1 11-15 and 20, derived from their molecular X-ray structures and from their B3LYP-optimized geometries are in a good agreement.
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.
