排序方式: 共有71条查询结果,搜索用时 15 毫秒
41.
P. Bharali R. Saikia R. K. Boruah R. L. Goswamee 《Journal of Thermal Analysis and Calorimetry》2004,78(3):831-838
Hydrolysis of ZnO in acidic pH provides a facile route for synthesis of layered double hydroxides (LDH) bearing Zn2+ with Cr3+ and Al3+ without having carbonate ion in the inter-layer position. The thermal decomposition of the prepared LDH show that with the increase of Cr3+ content in the system there is an increase in the thermal stability of the compounds. In case of Zn-Cr LDH there is a non-mass loss transition around 420°C. Segregation of parent LDH structure to a bivalent oxide and a spinel takes place in both Zn-Cr and Zn-Al LDH only at temperatures above 550°C.Authors are grateful to Director R. R. L. Jorhat for his kind permission to publish the work, as well as acknowledgement is due to Prof. Herbert Poellmann of University of Halle, Germany for some powder XRD runs. Also, acknowledgement is due to Ministry of Environment and Forests, Govt. of India for some financial assistance. 相似文献
42.
Abhijit Boruah Manash Protim Borpuzari Rahul Kar 《Journal of computational chemistry》2020,41(4):295-304
Performance of the density functionals mainly depends on the proper approximation of exchange-correlation functionals. Modification of various parameters of such functionals, according to the demand of the system, has brought their accuracy level to a new height. Recent reports highlight that Long-range Corrected (LC) functionals are not encouraging in reproducing orbital energies in solvent. Therefore, in this article, we have proposed a tuning scheme for the LC functional for improved orbital energies. In this scheme, the optimized long-range HF exchange and the dielectric constant of the medium are included to modify the form of functionals. The proposed tuning is tested over a set of 103 molecules from IP131 database and fifteen solvent dielectrics. The tuned range separated functionals reproduce orbital eigenvalues in solvent continuum with good accuracy. More importantly, there is a consistency in the error for the tuned functional across the solvent media. © 2019 Wiley Periodicals, Inc. 相似文献
43.
Dehydration of oximes and amides to nitriles was carried out using the AlCl(3) x 6H(2)O/KI/H(2)O/CH(3)CN system. It produced isoquinoline derivatives 8a-c (Bischler Naperialski reaction) when reacted with amides 7a-c in hydrated media. Also, the keto oximes produced anilides (Beckmann rearrangement) with the system under the same reaction conditions. 相似文献
44.
Synthesis of white microcrystalline oxodiperoxotungstate(VI) complexes, K[WO(O2)2(L)(H2O)]·H2O, (L ?= ?salicylate, 5-chlorosalicylate, 4-hydroxybenzoate) have been achieved from reaction of Na2WO4·2H2O with 30% H2O2 and the respective hetero-ligands at pH Ca. 7–7.5 in aqueous medium. The newly synthesized compounds were comprehensively characterized by elemental analyses, spectral studies, room temperature magnetic moment measurements and mass spectrometric studies. Infrared spectra suggest that, peroxo groups are bonded to the WO+4 center in a triangular bidentate (C2v) fashion and the hetero-ligands benzene-core hydroxycarboxylic acids viz. salicylic acid, 5-chlorosalicylic acid, 4-hydroxybenzoic acid in anoinic form are coordinated in monodentate manner. Compounds are fairly stable in aqueous solution for sufficient period of time. The results of mass spectrometric analysis lend support to the molecular composition of the complexes ascertained on the basis of elemental analyses and spectroscopic studies. Compound potassium(aquo)(5-chlorosalicylato)oxodiperoxotungstate(VI)monohydrate, K[WO(O2)2(5-chlorosalicylate)(H2O)]·H2O, act as an oxidant of bromide ion in aqueous phase bromination of chosen organic substrates to their corresponding bromo organics. Density Functional Theory (TD-DFT) calculations were performed on the synthesized complexes substantiated the experimentally obtained results. The TD-DFT optimized structures are in excellent agreement with the results of elemental analyses, spectral as well as mass spectrometric data. 相似文献
45.
Bhattacharjee Maitri Boruah Smriti Rekh Dutta Purkayastha R. N. Maniukiewicz Waldemar Chowdhury Shubhamoy Maiti Debasish Akhtar Tamanna 《无机化学学报》2013,29(18)
以甲醇为介质,合成了3种新的席夫碱配体HL1(2-hydroxybenzaldehyde2-(2-oxo-1,2-diphenylethylidene)hydrazone)、HL2(4-hydroxybenzaldehyde2 -(2 - oxo- 1,2 -diphenylethylidene)hydrazone)和 L3(2 -methoxybenzaldehyde2-(2-oxo-1,2-diphenylethylidene)hydrazone)的Cu(Ⅱ)配合物1~3。通过元素分析、光谱方法、磁化率测量和密度泛函理论(DFT)计算对配合物进行了表征。通过单晶X射线衍射研究对合成的配体进行了结构表征。通过DFT计算确定了配合物的优化结构。通过紫外可见吸收光谱和荧光发射光谱研究了配合物与小牛胸腺DNA(CT-DNA)的结合能力。吸收光谱研究揭示了增色效应,并提出了与CT-DNA相互作用的可能模式。溴化乙锭(EB)竞争结合研究表明,配合物可以取代 DNA-EB 加合物中的 DNA,且配合物可能以嵌入模式与 CT-DNA结合。配合物对革兰氏阴性肺炎克雷伯菌、大肠杆菌、鲍氏志贺菌和革兰氏阳性金黄色葡萄球菌的体外抗菌活性研究表明,配合物2对肺炎克雷伯菌和鲍氏志贺菌具有明显抗菌活性,但配合物1和3没有表现出任何显著的抗菌活性。 相似文献
46.
A simple and efficient catalytic system has been developed by adsorption of copper salt in the interlayers of montmorillonite K-10. The catalytic system impressively exercises the green chemistry perspective leading to effortless recovery and recyclability for the cross-coupling of arylboronic acids and N-nucleophiles. The effect of catalytic activity was studied for electronically diverse arylboronic acids and imidazoles relying on various optimizations under optimum thermal condition. The catalytic system was characterized and the morphology was determined. 相似文献
47.
Junali Gogoi Pranjal Bezbaruah Pallabi Saikia Jonalee Goswami Pranjal Gogoi Romesh Chandra Boruah 《Tetrahedron letters》2012,53(12):1497-1500
A facile synthesis of a novel class of steroidal A/B/D-ring annulated tetrazolo[1,5-a]pyridine derivatives has been accomplished via intramolecular 1,3-dipolar cycloaddition reaction of azide with nitrile in aprotic solvent. The synthesis of D-ring annulated tetrazolo[1,5-a]pyridine in alcohol showed incorporation of an alcohol molecule into the heterocyclic system. 相似文献
48.
Hadis Koolivand Alireza Sharifa Ehsan Chehrazi Mehdi Razzaghi Kashani Seyed Mohamad Reza Paran 《Polymer Science Series A》2016,58(5):801-809
The effect of graphene oxide (GO) nanosheets on the CO2/CH4 separation performance of a rubbery (poly(dimethylsiloxane), PDMS) as well as a glassy (polyetherimide, PEI) polymer is studied. Interfacial interactions between the nanosheets and both polymers are revealed by FTIR and SEM. The results of gas permeation through the membranes demonstrate that GO nanosheets enhance CO2/CH4 diffusivityselectivity of PEI and CO2/CH4 solubility-selectivities of the PEI and PDMS polymers, while diminish CO2/CH4 diffusivity-selectivity of PDMS. Furthermore, the possibility of overcoming the common tradeoff between CO2 permeability and CO2/CH4 selectivity of rubbery and glassy polymers by incorporating very low amounts of graphene oxide nanosheets is addressed. In other words, at 0.25 wt % GO loading, the PEI membrane shows simultaneous enhancement of CO2 permeability (16%) and CO2/CH4 selectivity (59%). Also, for the PDMS membrane simultaneous enhancement of CO2 permeability (29%) and CO2/CH4 selectivity (112%) is occurred at 0.5 wt % GO loading. Finally, the capability of the well known Nielsen model to predict the gas permeability behavior of the nanocomposites is investigated. 相似文献
49.
A simple,quick and novel protocol for biaryl synthesis using LiCl‐promoted in situ‐generated Pd nanoparticles
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Parmita Phukan Preeti Rekha Boruah Praveen Singh Gehlot Arvind Kumar Diganta Sarma 《应用有机金属化学》2018,32(2)
This paper describes a simple and a very quick protocol for biaryl synthesis using the Suzuki–Miyaura cross‐coupling reaction. A quintessential role of salting‐out agent LiCl was observed in the Suzuki–Miyaura cross‐coupling reaction that enhanced the reduction rate of Pd (II) to a considerable extent, resulting in the formation of nanosized palladium in a few seconds. The isolated Pd nanoparticles were characterized with X‐ray diffraction, dynamic light scattering, TGA, transmission electron microscopy and scanning electron microscopy‐dispersive X‐ray spectroscopy. The Suzuki–Miyaura cross‐coupling reaction proceeded very well with the in situ‐generated Pd nanocatalysts furnishing the desired biaryl adducts with excellent yields. 相似文献
50.
Arylidenemalononitrile undergoes facile exchange of dicyano methylene group with β-formyl steroidal enamide as well as aromatic aldehydes under mild base catalysed reaction. 相似文献