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51.
The photochemical and photophysical properties of peripheral and nonperipheral zinc and indium phthalocyanines containing 7‐oxy‐3,4‐dimethylcoumarin synthesized were investigated in this study. 7‐Hydroxy‐3,4‐dimethylcoumarin ( 1 ) was synthesized via Pechmann condensation reaction and then the phthalonitrile derivatives [4‐(7‐oxy‐3,4‐dimethylcoumarino)phthalonitrile ( 2 ) and 3‐(7‐oxy‐3,4‐dimethylcoumarino)phthalonitrile ( 3 )] were synthesized by nucleophilic aromatic substitution. Phthalocyanine compounds containing coumarin units on peripheral ( 4 and 5 ) and nonperipheral ( 6 and 7 ) positions were prepared via cyclotetramerization of phthalonitrile compounds. All compounds' characterizations were performed by spectroscopic methods and elemental analysis. The phthalocyanine derivatives' ( 4–7 ) photochemical and photophysical properties were studied in DMF. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yields) properties of these novel phthalocyanines ( 4 – 7 ) were studied in DMF. They produced good singlet oxygen (e.g., ΦΔ = 0.93 for 7 ) and showed appropriate photodegradation (in the order of 10?5), which is very important for photodynamic therapy applications. 相似文献
52.
Baris Kiskan Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2014,52(20):2911-2918
In this work, a self‐healing strategy for poly(propylene oxide)s bearing coumarine‐benzoxazine units (PPO‐CouBenz)s based on light induced coumarine dimerization reactions is described. Four different types of poly(propylene oxide) amines with molecular weights ranging from 440 to 5000 Da were reacted with formaldehyde and 4‐methyl‐7‐hydroxycoumarin to yield desired (PPO‐CouBenz)s. The crosslinked polymer films were prepared by solvent casting of various compositions of PPO‐CouBenzs in chloroform followed by thermal ring opening reaction of benzoxazine groups at 210–240 °C. Thermal curing and thermal stability of the initial PPOs and final products were investigated. Using allyl benzoxazine in the formulation, it was demonstrated that the toughness of the films was improved. Photoinduced healing of coumarin‐based cured PPO‐CouBenz polymer films was investigated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2911–2918 相似文献
53.
Jun-Ying Zhang Ian W. BoydB.J. O'Sullivan P.K. HurleyP.V. Kelly J.-P. Sénateur 《Journal of Non》2002,303(1):134-138
We report the deposition of thin titanium dioxide films on Si(1 0 0) and silica glass at low temperatures between 200 and 350 °C by a technique of ultraviolet-assisted injection liquid source chemical vapor deposition (UVILS-CVD) with 222 nm radiation. The composition and optical properties of the films deposited have been studied using a variety of standard characterisation methods. A strong absorption peak around 438 cm−1, corresponding to Ti-O stretching vibration, was observed by Fourier transform infrared spectroscopy for different deposition temperatures. Nanostructured films on Si wafers were observed by atomic force microscopy while X-ray diffraction results showed that crystalline TiO2 layers could be formed at deposition temperatures as low as 210 °C. The deposition kinetics and influence of the substrate temperature on the film are discussed. The activation energy for this photo-CVD process at temperatures between 200 and 350 °C was found to be 0.435 eV. This is much lower than the value (Ea=5.64 eV) obtained by conventional thermal CVD. The thicknesses of the films grown, from several nanometers to micrometers can be accurately controlled by changing the number of drops introduced by the injection liquid source. Under optimum deposition conditions, refractive index values as high as 2.5 and optical transmittance of between 85% and 90% in the visible region of the spectrum can be obtained. 相似文献
54.
Koichi Awazu 《Journal of Non》2004,337(3):241-253
The structure of amorphous SiO2 exposed to ArF excimer laser irradiation was examined. Threshold fluence for causing ablation with a single pulse depended on sample preparation: more specifically, 1 J/cm2 for thermally grown SiO2 films on silicon and 2.5 J/cm2 for bulk SiO2. It was found that the bond angle of Si-O-Si was reduced by irradiation near the interface of thermally grown SiO2 films. In contrast, evolution of the bond angle by irradiation was absent in both the bulk SiO2 and SiO2 film-near the top surface, even though the concentration of puckered four-membered rings deduced from Raman spectra dramatically increased. It is assumed that planar three-membered rings were generated in the SiO2 thin layer near the interface, and puckered four-membered rings were generated in the bulk SiO2. The concentration of both the Si3+ and Si2+ structure was increased at a fluence of 800 mJ/cm2 with an increasing number of pulses, although generation of both was absent at higher fluence for a single pulse. The author proposes that the structure of SiO2 is created by flash heating and quenching by pulse laser irradiation. Structural similarities were found between the irradiated SiO2 and SiO2 at high temperatures. 相似文献
55.
Beena Tyagi Manish K. Mishra Raksh V. Jasra 《Journal of molecular catalysis. A, Chemical》2008,286(1-2):41-46
Nano-crystalline sulfated-zirconia solid acid catalyst has been studied for microwave-assisted solvent free synthesis of hydroxy derivatives of 4-methyl coumarin by Pechmann reaction. The catalyst showed good activity for activated m-hydroxy phenol substrates, viz., phloroglucinol and pyrrogallol with ethyl acetoacetate for the synthesis of 5,7-dihydroxy 4-methyl coumarin and 7,8-dihydroxy 4-methyl coumarin, respectively, showing significant yields ranging from 78 to 85% within 5–20 min at 130 °C. However, the less activated phenol and m-methyl phenol was observed to be inactive for the synthesis of 4-methyl coumarin and 4,7-dimethyl coumarin, respectively, under the studied experimental conditions. 相似文献
56.
JIANG Hao ZOU Hao XIA Peng ZHANG Qian 《结构化学》2008,27(12):1423-1426
The title compound, C18H17BrO6 (Mr = 409.23), was synthesized as angiogenesis inhibitor and structurally characterized by ^1H-NMR, ^13C-NMR, MS, elemental analysis and X-ray single-crystal diffraction. Structure analysis indicates that the title compound is of triclinic, space group P1^-, with a = 8.100(3), b = 10.536(4), c = 11.689(5)A, a = 67.405(7), βl = 69.736(3), γ = 88.510(5)°, V = 857.3(5) A^3, Z = 2, Dc = 1.585 g/cm^3, μ = 2.429 mm^-1, F(000) = 416, the finial R = 0.0356 and wR = 0.0929 for 2541 observed reflections. The bond lengths of C(7)-C(16) proved that the title compound possesses coumarin rather than flavone scaffold. 相似文献
57.
Xiaodong Jia Xingzeng Zhao Ming Wang Yu Chen Yunfa Dong Xu Feng 《Chemistry of Natural Compounds》2008,44(6):692-695
Two new coumarin biosides, tert-O-β-D-apiofuranosyl-(1→6)-O-β-D-glucopyranosyl-byakangelicin (1) and 2′-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranosyl-peucedanol (2), were isolated from the fresh roots of Angelica dahurica. The structures of the new compounds were elucidated on the basis of spectral analysis.
Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 561–563, November–December, 2008. 相似文献
58.
Dinesh Singla Prof. Vijay Luxami Prof. Kamaldeep Paul 《European journal of organic chemistry》2023,26(34):e202300531
Palladium-catalyzed [4+2] oxidative annulation of coumarin-benzimidazoles with olefins for the synthesis of polycyclic aromatic hydrocarbons have been achieved. This synthetic protocol gives access to a wide range of structurally distinct imidazo[1,2-a]chromeno[3,4-c]pyridines in moderate to good yield with wide functional group tolerance. Further, photophysical properties of annulated scaffolds have been examined, which discloses their interesting solvatochromic emission behaviors. 相似文献
59.
Venkata Swamy Tangeti Ramesh Varma K. G. V. Siva Prasad K. V. V. V. Satyanarayana 《合成通讯》2016,46(7):613-619
An efficient method was developed for the synthesis of dihydrofuran substituted coumarin from a one-pot, four-component reaction of 2-hydroxy aromatic aldehydes, 6-methyl, 4-hydroxy pyranone, aromatic aldehyde, and pyridinium ylide in the presence of tri-ethylamine under microwave irradiation. The reaction proceeds under solvent-free conditions to afford C3-dihydrofuran substituted coumarin in a diastereoselective manner in good yields (71–89%). 相似文献
60.
The chloroform fraction of methanol (MeOH) extract of the aerial parts of Launaea mucronata was in vitro investigated for cytotoxicity against HCT116, HepG2 and MCF-7 cell lines, and resulted with IC50 = 20.0, 18.6 and 14.30 μg/mL, respectively. The chloroform fraction of the MeOH extract was subjected to further fractionation, which led to the isolation of two new coumarin compounds (6-isobutyl coumarin and 6-isobutyl-7-methyl- coumarin). The structures of the new compounds were elucidated by high field 1D and 2D NMR and ESI-MS spectroscopies. Low polar fractions revealed the isolation of other known triterpene compounds which were identified according to its spectral data and comparison with the literature. New coumarin compounds show high cytotoxicity against MCF-7, HCT116 and HepG2 cell lines. 相似文献