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991.
Prasada Raju V. N. K. V. Vetukuri Ravindra Vedantham Vijayavitthal Thippannachar Mathad Pratap Reddy Padi Vijaya Anand Ramasamy 《Helvetica chimica acta》2011,94(4):592-596
An efficient and concise synthesis of valacyclovir hydrochloride ( 4 ), which is a prodrug of acyclovir ( 3 ) is described. The synthesis was accomplished in two stages by coupling acyclovir with (2S)‐2‐azido‐3‐methylbutanoic acid followed by reduction (Scheme 2). 相似文献
992.
Birendra Babu Adhikari Manju Gurung Hidetaka Kawakita Keisuke Ohto 《Journal of inclusion phenomena and macrocyclic chemistry》2011,71(3-4):479-487
Complexation behavior of plural ion-exchangeable p?Ct-butylcalix[5]arene pentacarboxylic acid derivative towards trivalent indium has been investigated along with its monomeric analog from weakly acidic media into chloroform. The cyclic structure of calixarene ligand providing certain cavity and cooperativity of functional groups significantly affect the complexation behavior and calixarene derivative is an excellent extractant over monomeric analog. The extraction mechanism is ion exchange and carboxylic acid groups are adequate functional sites for extraction. Mononuclear and/or polynuclear species of indium and monomeric or bridged dimeric species of calixarene are involved in complexation and the composition of extracted complex varied with solution pH. One mole of calix[5]arene derivative tend to extract 3.5 mol of indium. The loaded indium was quantitatively back extracted with 1 mol dm?3 hydrochloric acid solution. 相似文献
993.
994.
Anbu S Kandaswamy M Kamalraj S Muthumarry J Varghese B 《Dalton transactions (Cambridge, England : 2003)》2011,40(28):7310-7318
A new bis-phenanthroline dicopper(II) complex has been synthesized and characterized by elemental analysis and spectroscopic methods. The molecular structure of the dinuclear Cu(II) complex [Cu(2)(μ-CH(3)COO)(μ-H(2)O)(μ-OH)(phen)(2)](2+) (phen = 1,10-phenanthroline) (1) was determined by single crystal X-ray diffraction technique. The coordination environment around each Cu(II) ion in complex 1 can be described as slightly distorted square pyramidal geometry. The distance between the CuCu centers in the complex is found to be 2.987 ?. The electronic, redox, phosphate hydrolysis, DNA binding and DNA cleavage have been studied. The antiproliferative effect of complex 1 was confirmed by the lactate dehydrogenase (LDH) enzyme level in MCF-7 cancer cell lysate and content media. The dicopper(II) complex inhibited the LDH enzyme as well as the growth of the human breast cancer MCF7 cell line at an IC(50) value of 0.011 μg ml(-1). The results strongly suggest that complex 1 is a good cancer therapeutic agent. Electrochemical studies of complex 1 showed an irreversible, followed by a quasi-reversible, one electron reduction processes between -0.20 to -0.8 V. Michaelis-Menten kinetic parameters for the hydrolysis of 4-nitrophenyl phosphate by complex 1 are k(cat) = 3.56 × 10(-2) s(-1) and K(M) = 4.3 × 10(-2) M. Complex 1 shows good binding propensity to calf thymus DNA, with a binding constant value of 1.3 (±0.13) × 10(5) M(-1) (s = 2.1). The size of the binding site and viscosity data suggest a DNA intercalative binding nature of the complex. Complex 1 shows efficient hydrolytic cleavage of supercoiled pBR322-DNA in the dark and in the absence of any external reagents, as demonstrated by the T4 ligase experiment. The pseudo-Michaelis-Menten kinetic parameters for DNA hydrolysis by complex 1 are k(cat) = 1.27 ± 0.4 h(-1) and K(M) = 7.7 × 10(-2) M. 相似文献
995.
Fujikawa K Ganesh NV Tan YH Stine KJ Demchenko AV 《Chemical communications (Cambridge, England)》2011,47(38):10602-10604
Herein, we report the invention of a novel expeditious concept for oligosaccharide synthesis. Unlike the classic orthogonal strategy based on leaving groups, the reverse approach is based on orthogonal protecting groups, herein p-methoxybenzyl and 4-pentenoyl, which allows for efficient oligosaccharide assembly in the reverse direction. 相似文献
996.
Vijaya Kabra Sonia Sharma Neelima Gupta Ashok Kumar Priyadarshi Meena 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2212-2219
Novel chiral 1,3,2-oxazaphospholane-2-sulfides incorporating a dihydropyridine ring have been synthesized via phosphorylation of 2-aminopyridinium salts, followed by in situ oxidation and cyclocondensation with 2-(alkylamino)ethanol. Cyclic organothiophosphates thus obtained have been screened for their antioxidant properties. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
997.
S. Ranganathan S. M. Babu P. R. Bangal S. Madhavendra S. R. Voleti 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1835-1843
Abstract Fixed quantities of silicic acid in isopropyl alcohol were treated with varying amounts of imidazole in the same solvent, left closed till complexation was complete (~7 days) and the resulting gels on slow evaporation (~30 days) afforded glassy solids, ranging from nodules to tubules, as seen by scanning electron microscope (SEM). In another strategy where soluble oligomers of silica along with monomers can be present and the reaction conditions remaining the same, rectangular cubes of varying sizes were secured. In the view of the significance and potential utility of this novel finding, only duplicate runs, which essentially afforded similar SEM are included here. Elemental analysis established the presence of imidazole in the complexes and their percentage composition was computed using thermo gravimetric analysis (TGA). FTIR showed organics, presence of hydrogen-bonded imidazole, Si?O?Si bonds, and complete absence of Si?O?C bonds. It is suggested that a pattern where hydrogen-bonded imidazole with itself and the polymer, is entombed in the polymerized silicic acid. Domains having such a profile most likely lead to the observed morphology.The present work vastly widens the scope for silicic acid—guest complexation and holds potential to discover a range of silica harboring materials. GRAPHICAL ABSTRACT 相似文献
998.
H. R. Prakash Naik H. S. Bhojya Naik D. S. Lamani T. Aravinda B. Vijaya Kumar B. Vinay Kumar 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):790-795
A new ligand dibenzo[h]quinolineno[1,3,7,9] tetraazacyclododecine-7,15 (14H, 16H)-dibenzene (L) and its Co(II)/Cu(II) metal complexes of type [MLX2] (Where (M = Co(II) (5), Cu(II) (6) and X = Cl) were synthesized and are well characterized by FT-IR, 1H-NMR, FAB mass elemental analysis, and electronic spectral data. The role of the cobalt/copper metals in photo-induced DNA cleavage reactions was explored by designing complex molecules having macrocyclic structure. Finally, we have shown that photocleavage of plasmid DNA is more efficiently enhanced when this macrocyclic ligand is irradiated in the presence of copper(II) than that of cobalt metal. 相似文献
999.
D.V.R. Murthy B.C. Jamalaiah A. Mohan Babu M. Jayasimhadri 《Optics Communications》2011,284(2):603-607
Nd3+ ions doped alkaline-earth titanium phosphate glasses were prepared by using the conventional melt quenching method. Absorption spectra were recorded and oscillator strengths of the transitions were calculated using area under the absorption bands. The energy level analysis was carried out by using free-ion Hamiltonian model. The three host dependent Judd-Ofelt intensity parameters, Ωλ (λ = 2, 4, and 6) were used to elucidate the structure of glassy matrix around Nd3+ ion as well as to determine the 4F3/2 metastable state radiative properties such as radiative transition probabilities, branching ratios and radiative lifetimes. The decay curves of all the three glasses show single exponential behavior. The discrepancy between the experimental and calculated lifetimes of emitting level was attributed to multiphonon relaxation. The achieved high quantum efficiencies for the 4F3/2 level indicate efficient laser emission at 1.06 μm in these glass systems. 相似文献
1000.
We show that the scalar sector needed for fermion mass generation when the flavor symmetry of the standard model is maximally gauged can consistently explain two anomalies reported recently by the CDF Collaboration-the forward-backward asymmetry in tt pair production and the dijet invariant mass in the Wjj channel. A pair of nearly degenerate scalar doublets with masses in the range 150-200 GeV explain these anomalies, with additional scalars predicted in the mass range 100-400 GeV. Consistency of such low scale flavor physics with flavor-changing processes is shown, and expectations for the LHC are outlined. 相似文献