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Indole-linked trisubstituted thiazoles (4) exhibit prominent fluorescence properties.
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We also recorded single-crystal X-ray diffraction (XRD) of compounds 4b and 9a for unambiguous structure determination. All of the products were fully characterized by spectroscopic techniques. Using a similar reaction strategy, the reaction of arylglyoxal, aryl thioamide, and 2,5-dihydroxy-1,4-benzoquinone provided structurally interesting bis-thiazoles having dihydroxy-1,4-benzoquinone linker (9). The reaction of arylglyoxal, indole, and aryl thioamides in the acetic acid medium under sealed heating conditions provided 3-(2,4-diarylthiazol-5-yl)-1H-indoles (4) in good to excellent yields. Herein, we report an efficient multicomponent reaction for the synthesis of trisubstituted thiazoles involving a one-pot C–C, C–N, and C–S bond-forming process from the readily available starting materials. In contrast, in the crystalline state, the carbazoyl-bearing D–A–D dye provided the best fluorescence quantum yield (0.35) because the radiation-free inactivation was suppressed by π–πF stacking at the donor site, which was confirmed by single-crystal X-ray analysis. Among the four synthesized perfluoronaphthalene D–A–D dyes, those bearing diphenylamino groups afforded the best fluorescence quantum yields in Et2O solution (0.60) and in PMMA film (0.65) because the propeller structure of the diphenylamino group that acts as a donor substituent effectively suppresses radiation-free deactivation. Notably, replacing the naphthalene ring with perfluoronaphthalene in the D–A–D dyes carrying the phenothiazine moiety not only stabilized the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels but also reduced the energy band gap to change the emission color from blue to yellow. The perfluoronaphthalene moiety in the D–A–D dyes served as a good electron-accepting aromatic ring with excellent intramolecular charge transfer properties, as determined by density functional theory calculations and measurements of the fluorescence properties in solution, in poly(methyl methacrylate) (PMMA) films, and in crystal form.
OXYGEN XML AUTHOR SERIES
In contrast to CuBr and CuCl, the combination of CuI with aniline-derived guanidine-amide exhibited high catalytic activity and a chiral induction effect, contributing to a high turnover frequency (9.70 × 10–4 s–1) in catalysis and ee%.Ī one-step route to a series of perfluoronaphthalene-based donor (D)–acceptor (A)–D fluorescent dyes with various electron-donating groups was developed. The affinity of the counterion for the Cu(I) center in the copper salt affected the deprotonation of phenylacetylene and the formation of guanidinium salt active species. Due to weak interaction between Cu(I) and the Ph group in the amide of guanidine, as well as the repulsion between the tert-butyl group in ketimine and the cyclohexyl group in guanidine, the copper acetylene preferred to attack isatin-derived ketimine from the re-face, leading to the S-configuration product with excellent stereoselectivity. The guanidinium salt-Cu(I) complex was the most active species in the addition of the C═N bond, in which copper acetylene coordinated to the O atom of the amide moiety, and the isatin-derived ketimine substrate was activated by hydrogen bonding as well as tert-butoxycarbonyl Guanidine-amide promoted the formation of highly nucleophilic copper acetylene species by abstracting the terminal proton of phenylacetylene with an imine moiety. In this work, we performed a mechanistic study of asymmetric alkynylation of isatin-derived N-Boc ketimine that was first reported by Feng, Liu, and co-workers (Chem. We expect that our work can not only shed light on the mechanisms of photocatalytic selective oxidation of toluene into benzaldehyde and other activation reactions of sp3 C–H bonds but also design and modulate highly efficient photocatalysts. The results clearly demonstrate the water-induced double-edged sword effects in the photocatalytic selective oxidation of toluene. In addition, the influences of the OH groups on catalysts (Ti–OH bonds) from photocatalytic water splitting are also considered. In this work, the Ti3O9H6 clusters in different solvents (water and toluene solvent) are used to study the water-induced effects in photocatalytic oxidation reactions in kinetics and thermodynamics using density functional theory (DFT) calculations. However, the effects of water on the photocatalytic selective oxidation of toluene into benzaldehyde remain elusive.
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Recently, water promotion effects in the selective oxidation of benzyl alcohol to benzaldehyde have been experimentally recognized and identified.