Synthesis, spectral characterization, in-vitro microbiological evaluation and cytotoxic activities of novel macrocyclic bis hydrazone

A macrocyclic hydrazone Schiff base was synthesized by reacting 1,4-dicarbonyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol and a series of metal complexes with this new Schiff base were synthesized by reaction with Co(II), Ni(II) and Cu(II) metal salts. The Schiff base and its complexes have been characterized by elemental analyses, IR, H-1 NMR, UV-vis, FAB mass, ESR spectra, fluorescence, thermal, magnetic and molar conductance data. The analytical data reveal that the Co(II), Ni(II) and Cu(II) complexes possess 2:1 metal-ligand ratios. All the complexes are non-electrolytes in DMF and DMSO due to their low molar conductance values. Infrared spectral data suggest that the hydrazone Schiff base behaves as a hexadentate ligand with NON NON donor sequence towards the metal ions. The ESR spectral data shows that the metal-ligand bond has considerable covalent character. The electrochemical behavior of the copper(II) complex was investigated by cyclic voltammetry. The Schiff base and its complexes have also been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Shigella dysentery, Micrococcus, Bacillus subtilis, Bacillus cereus and Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger, Penicillium and Candida albicans) by MIC method. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties. (C) 2009 Elsevier Masson SAS. All rights reserved.

Synthesis, spectral characterization and in vitro microbiological evaluation of novel glyoxal, biacetyl and benzil bis-hydrazone macrocyclic Schiff bases and their Co(II), Ni(II) and Cu(II) complexes

A series of binuclear Co(II), Ni(II) and Cu(II) complexes were synthesized by the template condensation of glyoxal, biacetyl or benzil bis-hydrazide, 2,6-diformyl-4-methylphenol and Co(11), Ni(II) or Cu(II) chloride in a 2:2:2 M ratio in ethanol. These 22-membered macrocyclic complexes were characterized by elemental analyses, magnetic, molar conductance, spectral, thermal and fluorescence studies. Elemental analyses suggest the complexes have a 2:1 stoichiometry of the type (M2LX2]center dot nH(2)O and Ni(2)LX(2)2H(2)O]center dot nH(2)O (where M = Co(II) and Cu(II); L = H2L1, H2L2 and H2L3; X = Cl; n = 2). From the spectroscopic and magnetic studies, it has been concluded that the Co(11) and Cu(11) complexes display a five coordinated square pyramidal geometry and the Ni(II) complexes have a six coordinated octahedral geometry. The Schiff bases and their metal complexes have also been screened for their antibacterial and antifungal activities by the MIC method. (C) 2011 Elsevier Ltd. All rights reserved.

SEC-MALDI-TOF mass spectral characterization of a hyperbranched polyether prepared via melt transetherification

An AB(2) monomer, 1-(2-hydroxyethoxy)-3,5-bis-(methoxymethyl)-2,4,6-trimethylbenzene, was synthesized from mesitol and melt-polycondensed in the presence of an acid catalyst via a transetherification process at 145-150 degreesC to yield a soluble, moderately high molecular weight hyperbranched polyether. The degree of branching in the polymer was calculated to be 0.78 by a comparison of its NMR spectrum with that of an appropriately designed model compound. The weight-average molecular weight of the hyperbranched polymer was determined to be 64,600 (weight-average molecular weight/number-average molecular weight = 5.2) by size exclusion chromatography (SEC) in CHCl3, with polystyrene standards. The origin of the broad molecular weight distribution, which could either be intrinsic to such hyperbranched structures or be due to structural heterogeneity, was further probed by the fractionation of the samples by SEC and by the subjection of each fraction to matrix-assisted laser desorption/ionization time-of-flight mass spectral analysis. The mass spectral analysis suggested the presence of two primary types of species: one corresponding to the simple branched structure and the other to macrocyclics. Interestingly, from the relative intensities of the two peaks, it was apparent that cyclization became favorable at higher conversions in the melt transetherification process. (C) 2002 Wiley Periodicals, Inc.

Synthesis and spectral characterization of cyclotriphosphazene based 18-membered macrocycles

New 18-membered cyclotriphosphazene-containing macrocycles 7-10 were obtained by 1 + 1 condensation reaction of dispiro-N3P3(C12H8O2)(2)((N(Me)N=CH)(2) N4C20H26)] (2) with N,N'-dimethyl-ethylenediamine-1,4-diyldimethylenebis(4-methyl-2-formylph enol) (3), N,N'-dimethyl-ethylenediamine-1,4-diyldimethylenebis(4,5-dimethyl-2-form ylphenol) (4), N,N'-dimethyl-ethylenediamine-1,4-diyldimethylenebis(5-chloro-2-formylph enol) (5) and N,N'-dimethyl-ethylenediamine-1,4-diyldimethylenebis(5-bromo-2-formylphe nol) (6), respectively. (C) 2012 Elsevier B.V. All rights reserved.

Synthesis, Spectral Characterization, Crystal Structure and Thermal Behavior of Tert-butyl 2,2-bis(2,4-dinitrophenyl)ethanoate

Tert-butyl 2,2-bis(2,4-dinitrophenyl)ethanoate was prepared from the ethanolic solution of 1-chloro-2,4-dinitrobenzene, tert-butyl 3-oxobutanoate and triethylamine. Acetyl group in tert-butyl 3-oxobutanoate has cleaved off during the formation of the title molecule. UV-VIS, IR, 1H NMR, 13C NMR, Proton-Proton COSY data and single crystal XRD results support the proposed structure. Flammability test, impact sensitivity test and TG/DTA studies at different heating rates on the synthesized molecule imply that it is an insensitive high energy density material.

Palladium(II) complexes as biologically potent metallo-drugs: Synthesis, spectral characterization, DNA interaction studies and antibacterial activity

Four novel mononuclear Pd(II) complexes have been synthesized with the biologically active Schiff base ligands (L-1-L-4) derived from 3-amino-2-methyl-4(3H)-quinazolinone. The structure of the complexes has been proposed by elemental analysis, molar conductance, IR, H-1 NMR, mass, UV-Vis spectrometric and thermal studies. The investigation of interaction of the complexes with calf thymus DNA (CT-DNA) has been performed with absorption and fluorescence spectroscopic studies. The nuclease activity was done using pUC19 supercoiled DNA by gel-electrophoresis. All the ligands and their Pd(II) complexes have also been screened for their antibacterial activity by discolor diffusion technique. (C) 2013 Elsevier B.V. All rights reserved.

Thermal analyses, spectral characterization and structural interpretation of Yb3+ doped TeO2-ZnO-ZnCl2 glasses

Bulk-lasses have been prepared in the TeO2-ZnO-ZnCl2 systems. Their characteristic temperatures were determined and analyzed. Raman and FT-IR spectra were used to analyze the effect of ZnCl2 on the structure and spectral properties of tellurite glasses and OH- groups in this glass system. The spectroscopic properties including absorption spectra, emission cross-sections and fluorescence lifetimes of Yb3+ in TeO2-ZnO-ZnCl2 were measured and calculated. It is demonstrated that the progressive replacement less than 20 mol% of TeO2 by ZnCl2 improves the thermal stability, removes the OH- groups, turns TeO4 bipyramidal arrangement into TeO3 (and/or TeO3+1) trigonal pyramids structures and results in the decrease of the symmetry of the structure, which increases the emission cross-sections and lifetimes. But when the content of ZnCl2 up to 30 mol%, the glass system becomes more hygroscopic and introduces more OH- groups, which decrease the emission cross-sections and shorten the lifetimes. The results show that the glass system with (TeO2)-Te-69-(ZnO)-Zn-10-20ZnCl(2)-1Yb(2)O(3) is a desirable component for active laser media for high power generation. (c) 2005 Elsevier B.V. All rights reserved.

Growth and spectral characterization of beta-Ga2O3 single crystals

Beta gallium oxide (beta-Ga2O3) single crystals were grown by the floating zone technique. The absorption spectra and the luminescence of the crystals were measured. The absorption spectra showed an intrinsic short cutoff edge around 260 nm with two shoulders at 270 and 300 nm. Not only the characteristic UV (395 nm), blue (471 nm) and green (559 nm) lights, but also the red (692 nm) light can be seen in the emission spectra. The deep UV light was attributed to the existing of quantum wells above the valence band and the red light was owed to the electron-hole recombination via the vicinity donors and acceptors. (c) 2006 Elsevier Ltd. All rights reserved.

Spectral characterization of transparent (Nd0.01Y0.94La0.05)(2)O-3 laser ceramics

The spectrum properties of transparent (Nd0.01Y0.94La0.05)(2)O-3 ceramics were investigated. It was found that all absorption bands of (Nd0.01Y0.94La0.05)(2)O-3 ceramics are broadened, of which the full width at half maximum of the peak centered at 804 nm is 8 nm and its absorption cross section is 1.02x10(-20) cm(2). The emission cross section of (Nd0.01Y0.94La0.05)(2)O-3 ceramics located at 1078 nm is 5.71x10(-20) cm(2) and its fluorescent lifetime is 0.214 ms, which are similar to those of 1.0 at. %Nd:Y2O3 ceramics. These indicate that (Nd0.01Y0.94La0.05)(2)O-3 transparent ceramics has excellent spectroscopic properties.

Expression, purification and spectral characterization of p21(Waf1/Cip1)

p21(Waf1/Cip1), best known as a broad-specificity inhibitor of cyclin/cyclin-dependent kinase complexes, can interact with various target proteins, and this ability relies on its structural plasticity. Therefore, studies on the structural properties of p(21) are very important to understand its structure-function relationship. However, detailed studies on its secondary structure and biophysical properties have been comparatively sparse. A human p(21) gene was cloned into the temperature expression vector pBV220 and transformed into Escherichia coli strain JM109.

Physical and spectral characterization of the human cyclin A gene and its interactions with anthracycline anticancer drugs

Over expression of cyclin A in human tumors has been linked to cancer by various experimental lines of evidence. However, physical and spectral characterization of the human cyclin A gene and its interactions with anticancer drugs have not been reported. Our gene sequence analysis, singular value decomposition method and melting studies in the presence of antitumor agents, daunomycin, doxorubicin and Hoechst 33258 showed that cyclin A gene had both AT-rich and GC-rich domains. For a ligand with unknown DNA binding specificity, this gene sequence can be used to differentiate its DNA binding preference.

Spectral characterization of families of split graphs

An upper bound for the sum of the squares of the entries of the principal eigenvector corresponding to a vertex subset inducing a k-regular subgraph is introduced and applied to the determination of an upper bound on the order of such induced subgraphs. Furthermore, for some connected graphs we establish a lower bound for the sum of squares of the entries of the principal eigenvector corresponding to the vertices of an independent set. Moreover, a spectral characterization of families of split graphs, involving its index and the entries of the principal eigenvector corresponding to the vertices of the maximum independent set is given. In particular, the complete split graph case is highlighted.

Synthesis, Spectral Characterization, Structural Studies and Biological Investigations of Transition Metal Complexes of Some Acid Hydrazones

This study concentrates the chemical properties of hydrazones due to its chelating capability and their pharmacological applications. Studies cover the preparation of different acid hydrazones and their structural studies and studies on their antimicrobial activity, synthesis and spectral characterization of different complexes of copper oxovanadium, manganese, nickel etc. Effect of incorporation of heterocyclic bases to the coordination sphere, change in the biological activity of acid hydrazones upon coordination, development of X-ray quality single crystals and its X-ray diffraction studies, studies on the redox behavior of the coordinated metal ions and correlation between the stereochemistry and biological activities.