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81.
N.Y. Abu-Thabit Izzat W. Kazi Hasan A. Al-Muallem Shaikh A. Ali 《European Polymer Journal》2011,(5):1113-1123
The zwitterionic monomer, ethyl 3-(N,N-diallylammonio)propanephosphonate and sulfur dioxide were cyclocopolymerized in DMSO using azobisisobutyronitrile or ammonium persulfate as initiators to afford a pH-responsive polyphosphonobetaine/SO2 (PPB/SO2) copolymer. The polymers, on treatment with HCl and NaOH, gave the aqueous solutions of the corresponding cationic polyphosphononic acid (CPP) and anionic polyphosphonate (APP). The solution properties of the PPB having two pH-responsive functionalities were investigated in detail by potentiometric and viscometric techniques. Basicity constants of the amine and phosphonate groups in APP were found to be “apparent” and as such follow the modified Henderson–Hasselbalch equation. The incorporation of SO2 moiety has resulted in the decrease of basicity constant of the nitrogens in the copolymer by staggering ?2 units of log K in compare to that of the corresponding homopolymer. The basicity difference is expected to have an effect on the chelating properties of the polymers. In contrast to many polycarbo- and -sulfobetaines, the PPB was all found to be soluble in salt-free water as well as in salt (including Ca2+ and Li+)-added solutions. The PPB demonstrated ‘antipolyelectrolyte’ viscosity behavior and found to have higher viscosity values in LiCl than in NaCl or NaI. 相似文献
82.
Mukund G. Kulkarni Sanjay W. Chavhan Mayur P. Desai Yunnus B. Shaikh Dnyaneshwar D. Gaikwad Attrimuni P. Dhondge Ajit S. Borhade Vijay B. Ningdale Deekshaputra R. Birhade Nagorao R. Dhatrak 《Tetrahedron letters》2010,51(34):4494-6381
Application of Wittig olefination-Claisen rearrangement protocol for the short synthesis of furo[2,3-b]indoles is described. 相似文献
83.
Pradeep Mathur Amrendra K. Singh Vinay K. Singh Shaikh M. Mobin 《Journal of organometallic chemistry》2010,695(7):950-141
Photolysis of a hexane solution of ferrocenylacetylene and sulfur powder in presence of Cr(CO)6 resulted in the formation of 2,6-diferrocenyldithiine and 2,5-diferrocenylthiophene. Similar reactions with Mo(CO)6 or W(CO)6 gave only the thiophene derivative. Formation of ferrocenyl-substituted thioketone complexes was observed in the reaction of ferrocenylacetylene with water and sulfur, in presence of W(CO)6. Use of D2O confirmed water as source of protons for the conversion of acetylenic CH to CH3. 相似文献
84.
S. D. Katore K. S. Adhav A. Y. Shaikh N. K. Sarkate 《International Journal of Theoretical Physics》2010,49(10):2358-2363
An exact higher dimensional LRS Bianchi type-I cosmological model is obtained in presence of thick domain walls in a scalar tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett. A113:467, 1985). Some physical and kinematical properties of the models are also discussed. 相似文献
85.
In this Letter we investigate the propagation of coupled nonlinear Alfven-spin and helicon-spin waves in a composite medium having the properties of both magnetic and semiconducting materials. We arrive at the nonlinear evolution equations for these coupled waves using the reductive perturbation method for which we obtain soliton solutions. We also discuss the limiting cases for the two materials separately. 相似文献
86.
Shaikh A. Ali N. Y. Abu‐Thabit Hasan A. Al‐Muallem 《Journal of polymer science. Part A, Polymer chemistry》2010,48(24):5693-5703
The zwitterionic monomer, ethyl 3‐(N,N‐diallylammonio)propanephosphonate, was cyclopolymerized in aqueous solutions using t‐butylhydroperoxide or ammonium persulfate as initiators to afford a polyphosphonobetaine (PPB). The protonation of P(?O)OEtO– and deprotonation of ? NH+ groups in PPB by HCl and NaOH, gave the corresponding cationic polyphosphononic acid (CPP) and anionic polyphosphonate (APP). The presence of two pH‐responsive functionalities in APP has led to establish the equilibria: APP ? PPB ? CPP, the position of which very much dictates the viscosity behavior of its aqueous solution. The PPB demonstrated “antipolyelectrolyte” viscosity behavior; however, in contrast to many polycarbo‐ and polysulfo‐betaines, it was found to be soluble in salt‐free water as well as in salt‐added solutions. Basicity constant (K1) of the amine group in APP, as determined by potentiometric technique, were found to be “apparent,” and as such followed the modified Henderson‐Hasselbalch equation. The study demonstrated a correlation between the basicity constants and viscosity values. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
87.
R. Santhosh Reddy Tanveer Mahamadali Shaikh Varun Rawat Pratibha U. Karabal Gajanan Dewkar Gurunath Suryavanshi Arumugam Sudalai 《Catalysis Surveys from Asia》2010,14(1):21-32
A novel, exceptionally stable titanium superoxide radical ion was prepared and its structure determined by FTIR, ESR, Raman spectroscopy, X-ray diffraction, thermogravimetric/differential thermal analysis and elemental analysis. This heterogeneous catalyst has been found to be effective for the selective oxidation of aromatic amines and phenols to the corresponding nitro aromatics and p-quinones, respectively. In addition, this non-toxic, inexpensive and reusable catalyst has also been used in aminobromination of olefins, which proceed to give the 1, 2-bromoaminated anti-Markovnikov product. A brief account of these results is summarized in this review. 相似文献
88.
Dhayal V Chaudhary A Choudhary BL Nagar M Bohra R Mobin SM Mathur P 《Dalton transactions (Cambridge, England : 2003)》2012,41(31):9439-9450
[Zr(OPr(i))(4)·Pr(i)OH] reacts with [HOSi(O(t)Bu)(3)] in anhydrous benzene in 1:1 and 1:2 molar ratios to afford alkoxy zirconosiloxane precursors of the types [Zr(OPr(i))(3){OSi(O(t)Bu)(3)}] (A) and [Zr(OPr(i))(2){OSi(O(t)Bu)(3)}(2)] (B), respectively. Further reactions of A or B with glycols in 1:1 molar ratio afforded six chemically modified precursors of the types [Zr(OPr(i))(OGO){OSi(O(t)Bu)(3)}] (1A-3A) and [Zr(OGO){OSi(O(t)Bu)(3)}(2)] (1B-3B), respectively [where G = (-CH(2)-)(2) (1A, 1B); (-CH(2)-)(3) (2A, 2B) and (-CH(2)CH(2)CH(CH(3)-)} (3A, 3B)]. The precursors A and B are viscous liquids, which solidify on ageing whereas the other products are all solids, soluble in common organic solvents. These were characterized by elemental analyses, molecular weight measurements, FAB mass, FTIR, (1)H, (13)C and (29)Si-NMR studies. Cryoscopic molecular weight measurements of all the products, as well as the FAB mass studies of 3A and 3B, indicate their monomeric nature. However, FAB mass spectrum of the solidified B suggests that it exists in dimeric form. Single crystal structure analysis of [Zr{OSi(O(t)Bu)(3)}(4)(H(2)O)(2)]·2H(2)O (3b) (R(fac) = 11.9%) as well as that of corresponding better quality crystals of [Ti(O(t)Bu){OSi(O(t)Bu)(3)}(3)] (4) (R(fac) = 5.97%) indicate the presence of a M-O-Si bond. TG analyses of 3A, B, and 3B indicate the formation of zirconia-silica materials of the type ZrO(2)·SiO(2) from 3A and ZrO(2)·2SiO(2) from B or 3B at low decomposition temperatures (≤200 °C). The desired homogenous nano-sized zirconia-silica materials [ZrO(2)·nSiO(2)] have been obtained easily from the precursors A and B as well as from the glycol modified precursors 3A and 3B by hydrolytic sol-gel process in organic media without using any acid or base catalyst, and these were characterized by powder XRD patterns, SEM images, EDX analyses and IR spectroscopy. 相似文献
89.
90.
Kundu T Sarkar B Mondal TK Mobin SM Urbanos FA Fiedler J Jiménez-Aparicio R Kaim W Lahiri GK 《Inorganic chemistry》2011,50(11):4753-4763
Using the [RuCl(μ-tppz)ClRu](2+) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine] platform for bridging two o-quinone/catecholate two-step redox systems (unsubstituted, Q(n), or 3,5- di-tert-butyl-substituted, DTBQ(n)), we have obtained the stable complexes [(Q(?-))Ru(II)Cl(μ-tppz)ClRu(II)(Q(?-))] (1) and the structurally characterized [(DTBQ(?-))Ru(II)Cl(μ-tppz)ClRu(II)(DTBQ(?-))] (2). The compounds exhibit mostly quinone-ligand-based redox activity within a narrow potential range, high-intensity near-IR absorptions (λ(max) ≈ 920 nm; ε > 50,000 M(-1) cm(-1)), and variable intra- and intermolecular spin-spin interactions. Density functional theory calculations, electron paramagnetic resonance (EPR), and spectroelectrochemical results (UV-vis-near-IR region) for three one-electron-reduction and two one-electron-oxidation processes were used to probe the electronic structures of the systems in the various accessible valence states. EPR spectroscopy of the singly charged doublet species showed semiquinone-type response for 1(+), 2(+), and 2(-), while 1 exhibits more metal based spin, a consequence of the easier reduction of Q as compared to DTBQ. Comparison with the analogous redox series involving a more basic N-phenyliminoquinone ligand reveals significant differences related to the shifted redox potentials, different space requirements, and different interactions between the metals and the quinone-type ligands. As a result, the tppz bridge is reduced here only after full reduction of the terminal quinone ligands to their catecholate states. 相似文献