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181.
Tarak Nath MandalSomnath Roy Samik GuptaBijan Kumar Paul Ray J. ButcherArnold L. Rheingold Susanta Kumar Kar 《Polyhedron》2011,30(9):1595-1603
Four oxovanadium(V) complexes of heterocycle based ditopic ligands PyPzOAP (N-[amino(pyridin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid), PyPzOAPz (N-[amino(pyrazin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid), PymPzOAP (N-[amino(pyridin-2-yl)methylidene]-1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-1H-pyrazole-3-carbohydrazonic acid) and PyPzCAP (5-methyl-1-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide) and a binuclear (di-μ-oxo) oxovanadium(V) complex of the ligand PymPzCAP (1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide) have been investigated. The ligands act as uninegative NNO tridentates donors for the VO2+ ion exhibiting their monotopicity. The ligands show varying emission properties due to the presence of fluophoric groups like 1-(2-pyridyl)pyrazole or 1-(2-pyrimidyl)pyrazole. The vanadium(V) complexes show fluorescence quenching with respect to the used ligands to a varying extent. The complexes were characterized by UV-Vis, IR, cyclic voltammetry and X-ray crystallography. 相似文献
182.
Navneet Soin Susanta Sinha Roy Surbhi Sharma Thomas Thundat James A. McLaughlin 《Journal of Solid State Electrochemistry》2013,17(8):2139-2149
Vertically aligned few layered graphene (FLGs) nanoflakes were synthesized by microwave plasma deposition for various time durations ranging from 30 to 600 s to yield graphene films of varying morphology, microstructure and areal/edge density. Their intrinsic electrochemical properties were explored using Fe(CN)6 3?/4? and Ru(NH3)6 3+/2+ redox species. All the FLG electrodes demonstrate fast electron transfer kinetics with near ideal ΔEp values of 60–65 mV. Using a relationship between electron transfer rate and edge plane density, an estimation of the edge plane density was carried out which revealed a moderation of edge plane density with increase in growth time. The pristine FLGs also possess excellent electrocatalytic activity towards oxygen reduction reaction (ORR) in alkaline solutions. This ORR activity can be further enhanced by exposing the pristine FLGs to nitrogen electron cyclotron resonance plasma. The metal free N-doped FLGs exhibit much higher electrocatalytic activity towards ORR than pristine FLGs with higher durability and selectivity than Pt-based catalysts. The excellent electrochemical performance of N-doped FLGs is explained in terms of enhanced edge plane exposure, high content of pyridinic nitrogen and an increase in the electronic density of states. 相似文献
183.
Susanta Mitra Afshin Ghanbari‐Siahkali Peter Kingshott Sren Hvilsted Kristoffer Almdal 《Journal of polymer science. Part A, Polymer chemistry》2004,42(24):6216-6229
The chemical degradation of an uncrosslinked pure fluoroelastomer (FKM; Viton A) in an alkaline environment (10% NaOH and 80 °C) was investigated. Scanning electron microscopy images showed that on a microscopic level, significant degradation substantially increased the surface roughness after prolonged exposure (e.g., 12 weeks). The molecular mechanisms of the chemical degradation processes at the surface were evaluated with X‐ray photoelectron spectroscopy and attenuated total reflectance/Fourier transform infrared spectroscopy. The results revealed that the early degradation proceeded primarily via dehydrofluorination reactions, creating double bonds in the rubber backbone. This further accelerated the degradation after longer exposure times. Furthermore, the resulting double bonds underwent nucleophilic attack by an aqueous NaOH solution to form several oxygenated species. All these species ultimately recombined to form crosslinks, as evidenced by the increase in the gel fraction and surface hardness (Shore A). The pronounced effect of chemical degradation through a reduction in the thermal stability of the pure FKM rubber upon exposure was also evident from thermogravimetric analysis and differential thermogravimetry. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6216–6229, 2004 相似文献
184.
Anindita Ghosh Shyambo Chatterjee Susanta Banerjee Hartmut Komber Brigitte Voit 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):509-517
A new trifluoromethyl-activated AB monomer has been successfully synthesized by Pd-initiated coupling of 4-bromo anisole with 4-fluoro-3-trifluoromethylphenylboronic acid followed by demethylation. The monomer leads to a semifluorinated poly(arylene ether) by nucleophilic displacement polymerization reaction. The AB monomer has been further copolymerized with a corresponding AB 2 monomer to form the corresponding semifluorinated hyperbranched (hb) poly(arylene ether). The resulting linear and hb poly(arylene ether)s exhibited weight average molecular weight of 75700 and 144100 g/mol, respectively. The hb copolymer exhibited better solubility in different organic solvents compared to the linear poly(arylene ether). The polymers showed excellent thermal stability up to 522°C at 10% wt loss in air and glass transition temperatures as high as 187°C. The mechanical properties of the linear poly(arylene ether) film 1a exhibited tensile strength at break of 89 MPa, elongation at break of up to 3% and a Young’s modulus value of 2.66 GPa. The films of the polymers were hydrophobic in nature and showed water contact angle as high as 93.6°. 相似文献
185.
Arpita Datta Moumita Maiti Susanta Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(2):931-937
Separation of no-carrier-added (NCA) 97Ru from bulk niobium target has been carried out for the first time using green analytical technique, aqueous biphasic system. 50 % (w/v) polyethylene glycol (PEG)-4000, against 2 M solutions of various salts such as Na-citrate, Na-tartarate, Na-malonate, Na2CO3, NaHSO3, Na2SO4, Na2S2O3 K2HPO4, K3PO4, K2CO3 and 4 M KOH were employed at room temperature for the extraction of NCA 97Ru from bulk niobium. Influence of molecular weight of PEG rich phase as well as pH of some salt rich phase (e.g., Na-tartarate) on the extraction behaviour of NCA 97Ru into PEG rich phase was also observed. In the presence of sodium-tartarate salt solution, when volume of PEG-4000: Na-tartarate was 3:1, 91 % of NCA 97Ru was extracted into the PEG rich phase without any contamination of niobium target. Dialysis of PEG rich phase containing NCA 97Ru was carried out against deionised water to obtained pure NCA 97Ru. 相似文献
186.
Swadesh Mandal Ajoy Mandal Susanta Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):861-863
The liquid–liquid extraction profile of molybdenum has been studied with di-(2-ethylhexyl) phosphoric acid from different HCl media. The careful study of extraction profile clearly indicates various species of molybdenum at different acid strengths, which have been interpreted with reference to established data. 相似文献
187.
No-carrier-added (nca) 208,209,210At was produced for the first time from 9Be induced reaction on thallium carbonate target at BARC-TIFR pelletron, Mumbai, India. The target of 4 mg/cm2 thickness was prepared by centrifugation technique. Nca At was separated from the thallium target by liquid–liquid extraction
using liquid cation exchanger HDEHP dissolved in cyclohexane and liquor ammonia. 相似文献
188.
G.N. Manjunatha Reddy Susanta Kumar Nayak T.N. Guru Row N. Suryaprakash 《Magnetic resonance in chemistry : MRC》2009,47(8):684-692
The scalar coupled proton NMR spectra of many organic molecules possessing more than one phenyl ring are generally complex due to degeneracy of transitions arising from the closely resonating protons, in addition to several short‐ and long‐range couplings experienced by each proton. Analogous situations are generally encountered in derivatives of halogenated benzanilides. Extraction of information from such spectra is challenging and demands the differentiation of spectrum pertaining to each phenyl ring and the simplification of their spectral complexity. The present study employs the blend of independent spin system filtering and the spin‐state selective detection of single quantum (SQ) transitions by the two‐dimensional multiple quantum (MQ) methodology in achieving this goal. The precise values of the scalar couplings of very small magnitudes have been derived by double quantum resolved experiments. The experiments also provide the relative signs of heteronuclear couplings. Studies on four isomers of dihalogenated benzanilides are reported in this work. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
189.
Photoelectrochemical corrosion of n-type α-PbO electrodes in aqueous Fe(CN)6
3−/4− and I−/I3
− electrolytes using the rotating ring-disk electrode technique has been investigated. The α-PbO thin film is found to be more
stable in I−/I3
− (48%) than in Fe(CN)6
3−/4− electrolyte (10%). Preferential adsorption of iodide ions decreases the photocorrosion reaction of holes with α-PbO. Addition
of CsI (0.4 mM) to the I−/I3
− electrolyte decreases the photocorrosion from 48% to less than 10%. Cs+ ions perhaps nullify the effect of negatively charged surface states of α-PbO, thus minimizing the trapping of holes at the
surface of α-PbO and hence decrease the possibility of photocorrosion of lead oxide with holes.
Received: 30 June 1998 / Accepted: 20 April 1999 相似文献
190.
Molybdenum and tungsten can be separated from each other by extraction with trioctylamine in hydrochloric acid medium. 相似文献