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171.
An easy and inexpensive method has been developed to access 1,2-disubstituted benzimidazoles following a one-pot sequential coupling/reduction/cyclization process under metal-free neutral conditions. 相似文献
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Snehasis Bhunia Rasha Hassanein Arnulf Materny Animesh K. Ojha 《Journal of Raman spectroscopy : JRS》2015,46(12):1191-1199
The interaction of K+ with the zwitterionic form of alanine (ZAla) is investigated using Raman spectroscopy and density functional theory calculations. The Raman spectra of an aqueous solution of Ala and its mixture with KOH at different molar concentrations [ZAla + xKOH, x = 1–5 M] have been recorded in the spectral region 400–1800 cm−1. The wavenumber position of the band at ~529 cm−1 shows a red shift of 14 cm−1, while the Raman band at ~634 cm−1 shows a blue shift of 10 cm−1 with the increasing x from 1 to 5 M. The intensity ratio I634/I529 is increased with increasing x, and it could be because of the increase in concentration of the [ZAla + K+] complex in the solution. The new Raman band appeared at ~1079 cm−1 in the Raman spectra of [ZAla + xKOH, x = 1–5] complex. To determine the most probable site for the interaction of K+ with ZAla, the structures of ZAla and the [ZAla + K+] were optimized at B3LYP/6‐311++G(d,p) level of theory. The electrostatic potential calculation carried out for ZAla reveals that the maximum density of electron is lying over COO−, and therefore, COO− would be the most probable site for the interaction of K+ with ZAla. The theoretically calculated Raman spectra of ZAla, [ZAla + K+] and the [ZAla− + K+] are in good agreement with experimentally observed Raman spectra. Thus, the Raman bands at ~529, 634, and 1079 cm−1 may be used as the Raman fingerprint for the interaction of K+ with COO− of the ZAla and ZAla−. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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ABSTRACT A new multielement sensitive fluorescent probe, 1-(2-(phenylthio)ethyl)-2-(pyridin-2-yl)-1H-benzo[d]imidazole (L), has been synthesized by the reaction between 2-(pyridyl) benzimidazole and 2-chloroethyl phenyl sulfide. Excitation and emission wavelength of L are at 330 and 371 nm, respectively. Among various transition and nontransition metal ions, it can selectively read Zn2+ ion as the emission wavelength of L undergoes a red shift by 31 nm upon binding with Zn2+ in methanol. In the presence of Cd2+, Hg2+, and other common cations, the emission wavelength of L remains unchanged, and thus allows us to discriminate Zn2+ from its congeners. Both L and its Zn2+ complex are well characterized by different spectroscopic techniques like 1H-NMR, ESI-TOF (+) mass, FT-IR, and elemental analysis data. The binding constant value of the complexation reaction between L and Zn2+ is found as 724.6 M?1 in methanol. Density functional theoretical (DFT) studies nicely demonstrate the red shift in the emission wavelength of L upon binding with Zn2+. 相似文献
176.
The reactions of [Ru(H)(Cl)(CO)(PPh3)3] with 3,5-di-tert-butyl-o-benzoquinone (dbq) and 3,4,5,6-tetrachloro-o-benzoquinone (tcq) have afforded the corresponding semiquinone complexes [RuII(dbsq)(Cl)(CO)(PPh3)2] and [RuII(tcsq)(Cl)(CO)(PPh3)2], respectively. The reaction of [Ru(H)2(CO)(PPh3)3] with tcq has furnished [RuII(tcsq)(H)(CO)(PPh3)2]. Structure determination of [Ru(dbsq)(Cl)(CO)(PPh3)2] has revealed that it is a model semiquinonoid chelate with two equal C---O lengths ( 1.291(6) and 1.296(6) Å). The complexes are one-electron paramagnetic (1.85μB) and their EPR spectra in fluid media display a triplet structure (g2.00) due to superhyperfine coupling with two trans-31P atoms (Aiso17 G). The stretching frequency of the CO ligand increases by 20 cm−1 in going from [Ru(dbsq)(Cl)(CO)(PPh3)2] to [Ru(tcsq)(Cl)(CO)(PPh3)2] consistent with electron withdrawal by chloro substituents. For the same reason the E1/2 values of the cyclic voltammetric quinone/semiquinone and semiquinone/catechol couples undergo a shift of 500 mV to higher potentials between [Ru(dbsq)(Cl)(CO)(PPh3)2] and [Ru(tcsq)(Cl)(CO)(PPh3)2]. 相似文献
177.
Summary Bivalent and trivalent cobalt complexes with 1-(2-pyridylazo)-2-naphthol (PAN), PAN+1, 10-phenanthroline and PAN+2, 2-bipyridyl were prepared and characterized by physico-chemical and magnetic measurements. The spectral studies suggest that PAN behaves as a bidentate ligand and is coordinated to metal ions through oxygen and (pyridine) nitrogen, whereas 1, 10-phenanthroline and 2, 2-bipyridyl are coordinated through (pyridine) nitrogen. The tentative (M–O) and (M–N) band assignments in the lower i.r. region, and magnetic moment data favour four coordination for the complexes studied. 相似文献
178.
A Diradical Approach towards BODIPY‐Based Dyes with Intense Near‐Infrared Absorption around λ=1100 nm 下载免费PDF全文
Dr. Yong Ni Sangsu Lee Minjung Son Prof. Dr. Naoki Aratani Masatoshi Ishida Dr. Animesh Samanta Prof. Dr. Hiroko Yamada Prof. Dr. Young‐Tae Chang Prof. Dr. Hiroyuki Furuta Prof. Dr. Dongho Kim Prof. Dr. Jishan Wu 《Angewandte Chemie (International ed. in English)》2016,55(8):2815-2819
A diradical approach to obtain stable organic dyes with intense absorption around λ=1100 nm is reported. The para‐ and meta‐quinodimethane‐bridged BODIPY dimers BD‐1 and BD‐2 were synthesized and were found to have a small amount of diradical character. These molecules exhibited very intense absorption at λ=1088 nm (?=6.65×105 M ?1 cm?1) and 1136 nm (?=6.44×105 M ?1 cm?1), respectively, together with large two‐photon‐absorption cross‐sections. Structural isomerization induced little variation in their diradical character but distinctive differences in their physical properties. Moreover, the compounds showed a selective fluorescence turn‐on response in the presence of the hydroxyl radical but not with other reactive oxygen species. 相似文献
179.
Animesh Roy Sudhir Arbuj Yogesh Waghadkar Manish Shinde Govind Umarji Sunit Rane Kashinath Patil Suresh Gosavi Ratna Chauhan 《Journal of Solid State Electrochemistry》2017,21(1):9-17
The SnO/SnO2 nanocomposites were synthesized using semisolvothermal reaction technique. These nanocomposites were prepared using different combination of solvents viz., ethanol, water, and ethylene glycol at 180 °C for 24 h. The synthesized nanocomposites were analyzed with various characterization techniques. Structural analysis indicates the formation of tetragonal phase of SnO2 for the sample prepared in ethanol, whereas for other solvent combinations, the mixture of SnO and SnO2 having tetragonal crystal structures were observed. The optical study shows enhanced absorbance in the visible region for all the prepared SnO/SnO2 nanocomposites. The observed band gap was found to be in the range of 3.0 to 3.25 eV. Microstructural determinations confirm the formation of nanostructures having spherical as well as rod-like morphology. The size of nanoparticles in ethanol-mediated solvent was found to be in the range of 5 to 7 nm. Thermogravimetric analysis indicate the weight gain around 1.3 wt% confirming the conversion of SnO to SnO2 material. The photocatalytic activity of synthesized nanocomposites was evaluated by following the aqueous methylene blue (MB) degradation. The sample prepared in ethylene glycol-mediated solvent showed highest photoactivity having apparent rate constant (Kapp) 0.62 × 10?2 min?1. 相似文献
180.