DNA interaction,anticancer, cytotoxicity and genotoxicity studies with potential pyrazine-bipyrazole dinuclear µ-oxo bridged Au(III) complexes

Molecular Diversity - Pyrazine-bipyrazole-based µ-oxo bridged dinuclear Au(III) complexes were synthesized and characterized by various spectrometric (1H-NMR, 13C (APT) NMR, FT-IR, Mass...     

35Cl NQR frequency and spin lattice relaxation study in 3,4-dichloronitrobenzene as a function of temperature and pressure

³⁵Cl NQR frequency and spin lattice relaxation time in 3,4-dichloronitrobenzene have been measured as a function of temperature and pressure. Two NQR signals were observed in the temperature range 77 to 300 K and pressure up to 5.1 kbar at 300 K. The contributions to the relaxation from the torsional motion of the molecule and reorientational motion of the nitro group have been analyzed on the basis of the Woessner and Gutowsky model. The temperature dependence of the average torsional lifetimes of the molecules, transition probabilities, and the activation energy for the reorientation of the nitro group was estimated. The pressure dependence of the NQR frequency in 3,4-Dichloronitrobenzene shows a nonlinear increase in NQR frequency with increase in pressure, indicating increased contribution from the static effects at higher pressures. A thermodynamic analysis of the data was carried out to determine the constant-volume temperature coefficients of the NQR frequency. The spin–lattice relaxation was found to be weakly dependent on pressure.     

35Cl NQR frequency and spin lattice relaxation time in 3,4‐dichlorophenol as a function of pressure and temperature

The pressure dependences of ³⁵Cl nuclear quadrupole resonance (NQR) frequency, temperature and pressure variation of spin lattice relaxation time (T₁) were investigated in 3,4‐dichlorophenol. T₁ was measured in the temperature range 77–300 K. Furthermore, the NQR frequency and T₁ for these compounds were measured as a function of pressure up to 5 kbar at 300 K. The temperature dependence of the average torsional lifetimes of the molecules and the transition probabilities W₁ and W₂ for the Δm = ±1 and Δm = ±2 transitions were also obtained. A nonlinear variation of NQR frequency with pressure has been observed and the pressure coefficients were observed to be positive. A thermodynamic analysis of the data was carried out to determine the constant volume temperature coefficients of the NQR frequency. An attempt is made to compare the torsional frequencies evaluated from NQR data with those obtained by IR spectra. On selecting the appropriate mode from IR spectra, a good agreement with torsional frequency obtained from NQR data is observed. The previously mentioned approach is a good illustration of the supplementary nature of the data from IR studies, in relation to NQR studies of compounds in solid state. Copyright © 2012 John Wiley & Sons, Ltd.     

Molecular dynamics in chloronitrobenzenes using NQR data

The torsional frequencies have been rigorously evalulated in the compounds 1,2,4,5-tetrachloro-3,6-dinitrobenzene and 1,3,5-trichloro-2,4-dinitrobenzene over an extended temperature range (77K–392K) using the experimental results of NQR and crystal structure data. The values have been compared with those obtained by using the X-ray thermal parameters.     

Growth and design of novel nonlinear optical material (NLO) ⿿ Glycine barium nitrate potassium nitrate (GBNPN) crystal

A potentially useful semi organic nonlinear optical (NLO) material ? glycine with barium nitrate and potassium nitrate (GBNPN) has been synthesized by slow evaporation technique. Good transparent GBNPN crystals were obtained in a time span of 3 weeks. The grown crystals were characterized by single crystal/powder XRD, UV?vis?IR absorption, FTIR, thermal analysis and powder SHG measurements have been studied. The grown crystals were thermally stable up to 137.53 °C. The GBNPN crystal exhibits second harmonic generation efficiency of about 1.35 times than that of potassium di hydrogen phosphate (KDP). Mechanical properties such as micro hardness (H_v) and Mayer's index, n, have been carried out by indentation method. The refractive index (μ) has been measured by the Brewster's angle method.     

Temperature‐ and pressure‐dependent study of 35Cl NQR frequency and spin lattice relaxation time in 2,3‐dichloroanisole

The temperature and pressure dependence of ³⁵Cl NQR frequency and spin lattice relaxation time (T₁) were investigated in 2,3‐dichloroanisole. Two NQR signals were observed throughout the temperature and pressure range studied. T₁ were measured in the temperature range from 77 to 300 K and from atmospheric pressure to 5 kbar. Relaxation was found to be due to the torsional motion of the molecule and also reorientation of motion of the CH₃ group. T₁ versus temperature data were analyzed on the basis of Woessner and Gutowsky model, and the activation energy for the reorientation of the CH₃ group was estimated. The temperature dependence of the average torsional lifetimes of the molecules and the transition probabilities were also obtained. NQR frequency shows a nonlinear behavior with pressure, indicating both dynamic and static effects of pressure. The pressure coefficients were observed to be positive for both the lines. A thermodynamic analysis of the data was carried out to determine the constant volume temperature coefficients of the NQR frequency. The variation of spin lattice time with pressure was very small, showing that the relaxation is mainly due to the torsional motions of the molecules. Copyright © 2010 John Wiley & Sons, Ltd.     

Phase diagram studies in two-surfactant ternary systems employing positron annihilation spectroscopy

Positron annihilation lifetime parameters in condensed media are sensitive to structural and conformational changes. This property has been exploited to study the phase diagrams of two ternary cationic surfactant systems. Positron lifetime measurements were performed in cetyltrimethylammonium bromide (CTAB)/water/hexanol and tetradecyltrimethylammonium bromide (TTAB)/water/pentanol systems having varying concentrations of hexanol and pentanol respectively. For both the systems, changes were observed in the positron lifetime parameters whenever a phase transformation occurred. The various phase boundaries demarcated by this technique agrees well with those obtained by other conventional techniques. Besides this, the present work suggests the existence of two kinds of lamellar structures referred to as DI and DII phases in both the systems, which were otherwise considered to be a single D phase by other conventional techniques. The existence of such lamellar structures has been demonstrated by a change in the trend of o-Ps lifetime when the system passes from one type of lamellar structure to the other type. The results of these investigations are presented.     

Annealing effects on zirconium nitride films

ZrN films were deposited by dc reactive magnetron sputtering on silicon substrates under optimized nitrogen partial pressure of 6×10⁻⁵ mbar. Structural, electrical and optical properties were systematically investigated. Films deposited at room temperature exhibited Schottky structure without any silicide interfacial layer. These films have electrical resistivity of 4.23×10⁻³ Ω cm, which were crystalline in nature, with cubic (1 1 1) orientation. Refractive index and extinction coefficient were found to be 1.95 and 0.43, respectively at a wavelength of 350 nm.

Samples were annealed for 1 h in air at two temperatures, 350 and 550 °C. Scanning electron microscopy (SEM) and energy dispersive analysis of X-rays (EDAX) showed alloy penetration pits. Extent of penetration was greater in the films, which were annealed at higher temperature (550 °C). Variation in refractive index was observed in the range of 1.95–1.80 at 350 nm, for the annealed films, with increase in grain size from 7.25 to 11.10 nm. Poly-crystalline nature has been observed with (1 1 1) and (2 0 1) orientations. Resistivity is found to increase from 4.23×10⁻³ to 6.21×10⁻³ Ω cm.     

Study of molecular motions in alkyl cyanobiphenyls using positron lifetime spectroscopy

Positron lifetime measurements have been carried out in two liquid-crystal-forming homologues of alkyl cyanobiphenyls, 7CB and 10CB. In each of these two compounds measurements were performed during the heating cycle of samples prepared either by quenching or by slow cooling from the respective liquid crystalline phase. In both compounds, the behavior of quenched and slow-cooled samples is found to be different. Unlike the slow-cooled sample, the material in the quenched sample seems to have transformed into a glassy solid. Theo-Ps pick-off lifetime in the quenched sample exhibits a strong temperature dependence. In each case, its value exhibits six broad peaks at various characteristic temperatures which have been ascribed to various motions associated with the molecules of these compounds. The quenched samples of 7CB and 10CB exhibit glass transitions at 268 and 266 K, respectively. The present work demonstrates an interesting application of positron lifetime spectroscopy (PLS).     

Investigations on Fe doped polyvinyl alcohol films with and without gamma (γ)-irradiation

This paper deals with the preparation of pure and ferric chloride (FeCl₃) doped polyvinyl alcohol (PVA) films by solution casting method. Optical and electrical properties were systematically investigated. We have found the decrease in optical band gap energy of PVA films on doping FeCl₃. The optical band gap energy values in the present work are found to be 3.10 eV for pure PVA, 2 eV for PVA:Fe³⁺ (5 mol%), 1.91 eV for PVA:Fe³⁺(15 mol%) and 1.8 eV for PVA:Fe³⁺(25 mol%). Direct current electrical conductivity (σ) of pure, FeCl₃ doped PVA films in the temperature range 70-127 °C has been studied. At 387 K dc electrical conductivity of pure PVA film is 5.5795 μ Ω⁻¹ cm⁻¹, PVA:Fe³⁺ (5 mol%) film is 10.0936 μ Ω⁻¹ cm⁻¹ and γ-Irradiated PVA:Fe³⁺ (5 mol%) film for 900 CGY/min is 22.1950 μ Ω⁻¹ cm⁻¹. The result reveals the enhancement of the electrical conductivity with γ-irradiation. FT-IR study signifies the intermolecular hydrogen bonding between Fe³⁺ ions of FeCl₃ with OH group of PVA.