1032-98-0Relevant articles and documents
Synthesis and free radical scavenging activity of coumarin derivatives containing a 2-methylbenzothiazoline motif
Khoobi, Mehdi,Emami, Saeed,Dehghan, Gholamreza,Foroumadi, Alireza,Ramazani, Ali,Shafiee, Abbas
, p. 588 - 594 (2011)
Coumarin and benzothiazole scaffolds can be found in a number of natural or synthetic antioxidants. In an effort to develop a novel radical scavenger and potential antioxidant, a series of coumarin derivatives containing 2-methylbenzothiazoline motif and related compounds was synthesized and evaluated for their DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS ?+ (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radicals scavenging activities. Among them, 7-hydroxy-3-(2-methyl-2,3- dihydrobenzo[d]thiazol-2-yl)-2H-chromen-2-one (3e) has shown a significant free radical scavenging activity. From the structure-activity point of view, it was found that phenolic coumarin ring and benzothiazoline moiety in target compounds may contribute to the scavenging activity against free radicals. A series of coumarin derivatives containing a 2-methylbenzothiazoline motif and related compounds were synthesized and evaluated for their DPPH and ABTS ?+ radicals scavenging activities. 7-Hydroxy-coumarin derivative 3e showed a significant free radical scavenging activity. Copyright
Accessing the long-lived emissive 3IL triplet excited states of coumarin fluorophores by direct cyclometallation and its application for oxygen sensing and upconversion
Wu, Wenting,Wu, Wanhua,Ji, Shaomin,Guo, Huimin,Zhao, Jianzhang
, p. 5953 - 5963 (2011)
We studied four cyclometallated Pt(ii) complexes, in which the thiazo-coumarin ligands (Pt-2, Pt-3 and Pt-4) or the phenylthiazo ligand (Pt-1) were directly cycloplatinated. Pt-2 shows intense absorption in visible region but other complexes show blue-shifted absorption. Room temperature phosphorescence was observed for all the complexes, and the emission wavelength is dependent on the size of the π-conjugation, not the intramolecular charge transfer (ICT) feature of the CN ligands. Pt-2 shows longer phosphorescence lifetime (τ = 20.3 μs) than other complexes (below 2.0 μs). Furthermore, Pt-2 shows phosphorescence quantum yield Φ = 0.37, whereas Pt-3 and Pt-4 show much smaller Φ values (0.03 and 0.01, respectively). DFT/TDDFT calculations indicate 3IL triplet excited states for the complexes. The complexes were used as for luminescence O2 sensing and triplet-triplet-annihilation (TTA) based upconversion. Stern-Volmer quenching constant KSV = 0.026 Torr-1 was observed for Pt-2, ca. 89-fold of that of Pt-3. TTA upconversion is achieved with Pt-2 (λem = 400 nm with λex = 473 nm, anti-Stokes shift is 0.47 eV, excitation power density is at 70 mW cm-2). The upconversion quantum yield with Pt-2 as triplet sensitizer is up to 15.4%. The TTET efficiency (KSV = 1.33 × 105 M-1, kq = 6.57 × 109 M-1 s-1. DPA as quencher) of Pt-2 is 34-fold of the model complex [Ru(dmb) 3][PF6]2. Our results show that the 3IL state can be readily accessed by direct cyclometallation of organic fluorophores and this approach will be useful for preparation and applications of transition metal complexes that show intense absorption in visible region and the long-lived emissive 3IL excited states.
A one-pot reaction to synthesize two types of fluorescent materials containing benzothiazolyl moiety
Yu, Tianzhi,Zhang, Chengcheng,Zhao, Yuling,Chai, Haifang,Fan, Duowang,Ma, Ying,Yao, Shanglei,Li, Wentao
, p. 274 - 279 (2013)
Two different types of fluorescent materials containing benzothiazolyl moiety, 2-(benzothiazol-2-yl)phenol derivatives and 3-(benzothiazol-2-yl) coumarin derivatives, were synthesized synchronously using ethyl cyanoacetate, appropriate aromatic aldehyde and 2-aminothiophenol as the starting materials under the catalysis of benzoic acid by one-pot reaction. This method has the advantages of mild reaction conditions, easy processing and low waste. All synthesized compounds were characterized by elemental analysis, IR, 1H NMR spectra. The structures of 2-(benzothiazol-2-yl)phenol derivatives, 2-(benzothiazol-2-yl)phenol (BTP) and 2-(benzothiazol-2-yl)naphthol (BTN), were determined by X-ray single crystal analysis. The UV-vis absorption and photoluminescence spectra of all synthesized compounds were investigated. The 2-(benzothiazol-2-yl)phenol derivatives exhibit bright green emissions and 3-(benzothiazol-2-yl)coumarin derivatives emit bright blue light in solutions.
The one-pot synthesis and fluorimetric study of 3-(2′-benzothiazolyl)coumarins
Zhou, Shihai,Jia, Jianhong,Gao, JianRong,Han, Liang,Li, Yujin,Sheng, Weijian
, p. 123 - 128 (2010)
A novel, piperidene-catalysed, one-pot synthesis of 3-(2′-benzothiazolyl)coumarins was undertaken, starting from salicylaldehydes, ethyl cyanoacetate and o-aminobenzenethiols in ethanol. Salicylaldehydes with electron-donating group gave optimum yields. The novel method is characterized by mild reaction conditions, simple procedure and low waste. All compounds were fluorescent in solution emitting either green light (490?nm) or blue light (440-460?nm). Two typical fluorescence peaks were found in the three-dimensional fluorescence spectra.
Tailoring C-6-Substituted Coumarin Scaffolds for Novel Photophysical Properties and Stimuli-Responsive Chromism
Chen, Chao-Tsen,Chen, Deng-Gao,Chou, Pi-Tai,Lan, Yi-Cheng,Liu, Yi-Hung,Singh, Ravinder,Wang, Chun-Hsiang
, p. 11557 - 11565 (2021/10/25)
A judicious strategy was utilized to envision the substantial regio-positional effects of substituents on the photophysical properties of the 2H-chromen-2-one-3-benzothiazole scaffold-based push-pull framework, named 6-X-CUMs. Among them, 6-NEt2-CUM reveals prominent excited-state intramolecular charge transfer with a large change of dipole moment (?μ ～18.23 D), hence displaying remarkable emission solvatochromism from the green (536 nm in cyclohexane) to far-red region (714 nm in dimethyl sulfoxide) and a high-temperature sensitivity (-0.23 nm °C-1). These, together with unique basicity and acido-/vaporchromism upon acidification elucidated by NMR and photospectroscopic studies, show stark contrast to the conventional 7-NEt2-CUM. The new series of these tailored 6-X-CUMs represents a new dimension in tailoring the photophysical properties for the development of a promising class of multistimuli-responsive materials.
Alumina as a support and catalyst for the synthesis of benzothiazoles in solvent-free condition
Ding, Mei-Fang,Chen, Chia-Pei,Lin, Shaw-Tao
, p. 645 - 649 (2013/10/22)
Arylbenzothiazole (4) and benzothiazolylcoumarins (5) were prepared by the condensation of 2-aminothiophenol (1) and hydroxybenzaldehydes (2) and 3-ethoxycarbonylcoumarinnin (3), respectively, in solvent- free condition. Of the solid support used,γ-Al2O3 demonstrated the best activity. Alinear regression line obtained from correlation between relative formation rate and Hammett constants with slope of 0.653 suggested that this condensation process is less sensitive to the substituents on the phenyl ring due to low efficacy of polarization in the solid state. In general, good yields (>80% yield) were obtained for the formation of 4. Conversely, yields of 5 were poor, because of γ-Al2O3 catalytic decomposition of 3 to form 2 (without P2O5) and coumarin (with P2O5).
