Synthesis,characterization and biological analysis of transition metal complexes with macro cyclic ligands derived from adipic acid,ethylenediamine with diethyloxalate and diethylmalonate

Macro-cyclic ligands from adipic acid, ethylenediamine with diethyloxalate and diethylmalonate and their respective metal complexes of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with macro cyclic ligands (LO) and (LM) L [N,N′-bis(2-aminoethyl)hexanediamide] were synthesized successfully. These metal complexes were characterized by Fourier transform infrared, ultraviolet visible spectrometry, proton nuclear magnetic resonance spectroscopy, and mass Spectrometry, CHNS and thermogravimetric analysis. The elemental analysis confirms the structures for Mn(II), Co(II) and Ni(II) complexes similar to octahedral geometry, Cu(II) complexes as a square planar geometry and Zn(II) complexes in the tetrahedral geometry. The molar conductivities of all the metal complexes were taken in 10^?3 M DMSO, and values of all the metal complexes showed their electrolytic nature which indicates the presence of chloride ions. Thermal analysis supports as the metal complexes are thermally stable. The result of antimicrobial activity against various microorganisms confirms that the metal complexes are potent bactericides and fungicides than the ligand. Metal complexes of LO with Cu(II) and Zn(II) were found to be highly active against S. typhimurium than the complexes of LM.

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Reactions under autogenic pressure at elevated temperature (RAPET) of various alkoxides: formation of metals/metal oxides-carbon core-shell structures

The RAPET reaction at 700 degrees C, of different alkoxides (Ti, V, and Si) led to three different nanocomposites. Carbon is the element common to all three structures. Carbon was found as the core in the decomposition of TEOS, as the shell in the decomposition of VO(OEt)3 and embedded in, or mixed completely with, TiO2 in the decomposition of Ti(OiPr)4. This novel method using only metallic alkoxide precursor, in the absence of catalyst, leads in a one-step process to core-shell structures.     

A simple experimental method to generate partially coherent optical bottle beam

An experimental study is carried out to investigate a special kind of three-dimensional intensity distribution of a partially coherent optical beam known as optical bottle beam produced by using an annular aperture and lens combination (Lens Aperture System). In this paper, we are demonstrating the experimental results of our observations. The investigation also includes the effects of coherence modulation and central obstruction of the annular aperture (used in Lens Aperture System) on the resultant partially coherent optical bottle beam. The method discussed in this paper is simple and cost effective.     

Phenyl-ring-bearing cationic surfactants: effect of ring location on the micellar structure

A series of isomeric cationic surfactants (S1-S5) bearing a long alkyl chain that carries a 1,4-phenylene unit and a trimethyl ammonium headgroup was synthesized; the location of the phenyl ring within the alkyl tail was varied in an effort to understand its influence on the amphiphilic properties of the surfactants. The cmc's of the surfactants were estimated using ionic conductivity measurements and isothermal calorimetric titrations (ITC); the values obtained by the two methods were found to be in excellent agreement. The ITC measurements provided additional insight into the various thermodynamic parameters associated with the micellization process. Although all five surfactants have exactly the same molecular formula, their micellar properties were seen to vary dramatically depending on the location of the phenyl ring; the cmc was seen to decrease by almost an order of magnitude when the phenyl ring was moved from the tail end (cmc of S1 is 23 mM) to the headgroup region (cmc of S5 is 3 mM). In all cases, the enthalpy of micellization was negative but the entropy of micellization was positive, suggesting that in all of these systems the formation of micelles is both enthalpically and entropically favored. As expected, the decrease in cmc values upon moving the phenyl ring from the tail end to the headgroup region is accompanied by an increase in the thermodynamic driving force (ΔG) for micellization. To understand further the differences in the micellar structure of these surfactants, small-angle neutron scattering (SANS) measurements were carried out; these measurements reveal that the aggregation number of the micelles increases as the cmc decreases. This increase in the aggregation number is also accompanied by an increase in the asphericity of the micellar aggregate and a decrease in the fractional charge. Geometric packing arguments are presented to account for these changes in aggregation behavior as a function of phenyl ring location.     

Quantum effect on parametric amplification characteristics in piezoelectric semiconductors

Using QHD model the parametric interaction of a laser radiation in an unmagnetised piezoelectric semiconductor has been studied. It is found that the Bohm potential in the electron dynamics enhances the gain coefficient of parametrically generated modes whereas reduces the threshold pump intensity.     

Electron paramagnetic resonance study of 3,4,5-trimethoxytetraphenyl porphyrinoxovanadium (IV) complex

3,4,5-Trimetoxytetraphenylporphyrinoxovanadium (IV) complex (3,4,5-TMVOTPP) was synthesized by a new one pot synthetic method. The complex was studied in the form of single crystal, powder (polycrystalline state), solution and frozen solution (glassy state) by electron paramagnetic resonance (EPR) between room temperature (RT) and liquid nitrogen temperature (LNT). Interestingly a well-resolved octet in the EPR spectrum at RT is observed in the pure paramagnetic state of the crystal. This observation is attributed to a greatly reduced dipolar interaction between paramagnetic vanadyl ions due to the large size of the molecule and the resultant stacking in the crystalline state. The line width of the EPR signals in single crystal at RT is approximately 3.3 mT which is more than the usual line width in diluted paramagnets ( approximately 1.5 mT) and is attributed to some kind of broadening effect akin to slow motion broadening. The line width in solvents is more than the crystal value but decreases appreciably at low temperatures. The decrease in line width at low temperature is attributed to the increase in spin-lattice-relaxation time and quenching of RT broadening motion. Only one octet is observed in the crystal EPR spectra which suggests only one formula unit per unit cell or a parallel/antiparallel ordering of V=O vectors in case the formula units per unit cell are more than one. This result needs verification by a detailed X-ray investigation. The crystalline field symmetry around the V(4+) metal ion is revealed to be axial by the observed angular dependence of the EPR spectrum and the powder EPR spectrum. No super hyperfine splitting of the hyperfine lines of the vanadyl ion is observed in solid state or diluted glass up to liquid nitrogen temperature. This suggests an expected weak in-plane pi-bonding with ligands. The spin Hamiltonian parameters for vanadyl ion in crystal, powder, diluted solutions and frozen glasses are evaluated and discussed.     

Substitutional effect of Cr ions on the properties of Mg–Zn ferrite nanoparticles

The effect of Cr³⁺ substitution in Mg–Zn ferrite, with a chemical formula Mg_0.5Zn_0.5Cr_xFe_2−xO₄ (x=0.0–1.0), synthesized by a sol–gel auto-combustion reaction is presented in this paper. The resultant powders were investigated by various techniques, including X-ray diffractometry (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), vibrating sample magnetometry (VSM), and DC resistivity. The XRD pattern revealed that the cubic spinel structure is maintained for the all the compositions. The particle sizes measured from XRD and TEM are in good agreement with each other. The cation distribution suggests that Mg²⁺, Cr³⁺ and Fe³⁺ have strong preference towards octahedral B-site. The theoretical lattice constant and experimental lattice constant match each other very well. The IR analysis supports the presently accepted cation distribution. The saturation magnetization decreases linearly with increasing Cr³⁺ content. Curie temperatures are obtained by the Laoria and AC susceptibility techniques. The dc resistivity has been investigated as a function of temperature and composition.