Characterisation of bhringaraj and guduchi herb by ICP-MS analysis, optical absorption, infrared and EPR spectroscopic methods.

Leaves of bhringaraj and guduchi herb of Kadapa district of Andhra Pradesh, India, are dried and powdered. ICP-MS analysis of samples indicates that copper is present in both the samples. An EPR study of guduchi sample also confirms the presence of Fe(III) whereas Eclipta alba confirms the presence of Fe(III), Mn(II) and Cu(II). Optical absorption spectrum of guduchi indicates that Cu(II) is present in rhombically distorted octahedral environment. NIR and IR results are due to carbonate fundamentals.

Optical absorption and EPR studies on beaverite mineral.

The behaviour of transition metal ions in beaverite mineral has been studied by spectroscopic techniques such as electron paramagnetic resonance and absorption spectroscopy in the UV-vis and NIR regions. The ground state of Cu(II) ion in beaverite is confirmed as (2)B(1g) since g(parallel)>g(perpendicular) (2.42>2.097). A resonance noticed at g=2.017 is ascribed to Fe(III) impurity. Two sets of three characteristic bands observed in the optical absorption spectra are assigned to the same transitions, (2)B(1g)-->(2)A(1g), (2)B(1g)-->(2)B(2) and (2)B(1g)-->(2)E(g) of Cu(II) ion in tetragonal field. The presence of Fe(III) bands is supportive evidence for iron impurity in the mineral. Mid infrared spectrum is due to overtones and combination tones of water and hydroxyl groups.

Synthesis, physico-chemical and DNA interaction studies of homo- and hetero-trinuclear complexes.

Synthesis and characterization of three new trinuclear metal complexes of type Cu3, Cu2Zn and Cu2Ni have been achieved by assembling simple mononuclear complexes, namely 2,2'-bipyridyl 3,4-dihydroxo benzaldehyde copper(II) complex and diethylenetriamine complexes of copper(II), nickel(II) and zinc(II) ions, through the reaction of coordinated ligands. The FAB mass spectra for the complexes show fragmentation pattern in accordance with the molecular formula. The frozen electron paramagnetic resonance (EPR) spectrum of tricopper complex shows two sets of parallel lines with approximately 2:1 ratio. The simulation has been carried out by considering dipolar interaction between the two types of copper ions present in the complex. The trimetallic complexes, Cu3, Cu2Ni and Cu2Zn show strong intercalation type of interaction with Calf thymus DNA in 0.02 mol L(-1) of phosphate buffer containing 60 mmol sodium chloride at pH 7.0 at room temperature. The binding constant is found to be in the order Cu3

Characterisation of prehnite by EPMA, Mössbauer, optical absorption and EPR spectroscopic methods.

A sample of prehnite from Rayalaseema zone of Andhra Pradesh, India containing about 2.565 wt.% Fe(2)O(3) is used in the present work. The mineral has been characterized by EPMA, optical absorption, EPR, NIR and Mössbauer techniques. Mössbauer studies confirm the presence of iron as an impurity in two sites. An EPR study on powder sample confirm the presence of Fe(III) impurity in the mineral. Optical absorption spectrum also indicates that Fe(III) impurity is present in two sites with octahedral structure. NIR results are due to water fundamentals.

Electron transfer reaction of oxo(salen)chromium(V) ion with anilines.

The kinetics of oxidation of 16 meta-, ortho-, and para-substituted anilines with nine oxo(salen)chromium(V) ions have been studied by spectrophotometric, ESIMS, and EPR techniques. During the course of the reaction, two new peaks with lambda(max) at 470 and 730 nm appear in the absorption spectrum, and these peaks are due to the formation of emeraldine forms of oligomers of aniline supported by the ESIMS peaks with m/z values 274 and 365 (for the trimer and tetramer of aniline). The rate of the reaction is highly sensitive to the change of substituents in the aryl moiety of aniline and in the salen ligand of chromium(V) complexes. Application of the Hammett equation to analyze kinetic data yields a rho value of -3.8 for the substituent variation in aniline and +2.2 for the substituent variation in the salen ligand of the metal complex. On the basis of the spectral, kinetic, and product analysis studies, a mechanism involving an electron transfer from the nitrogen of aniline to the metal complex in the rate controlling step has been proposed. The Marcus equation has been successfully applied to this system, and the calculated values are compliant with the measured values.

Single crystal EPR study of Cu(2+) in cobalt ammonium phosphate hexahydrate: a case of low hyperfine coupling constant and measurement of spin-lattice relaxation times.

Single crystal electron paramagnetic resonance (EPR) studies of Cu(II) doped cobalt ammonium phosphate hexahydrate have been carried out from 300 to 77 K, with single crystal rotation in all the three planes at 153 K, since the spectra are well resolved at this temperature. The angular variation studies indicate only one site in substitutional position with spin-Hamiltonian parameters as g: 2.404, 2.155, 2.063 and A: 11.58, 3.49, 2.07 mT. The reduction in one of the principal A value has been explained by considering considerable admixture of d(x(2)-y(2)) ground state with d(zeta(2)) excited state. The admixture coefficients of ground state wave function are: a = 0.2500; b = 0.9663; c = 0.0520; d = 0.0210; e = -0.0210, where a and b correspond to admixture coefficients for d(zeta(2)) and d(x(2)-y(2)) , respectively. Parameters kappa = 0.5140; P = 113 X 10(-4) cm(-1); alpha(2) = 0.7897; alpha = 0.8887; and alpha' = 0.5262 have also been calculated, indicating considerable covalency. The powder spectrum at room temperature is unresolved, whereas it is better resolved at 77 K, with spin-Hamiltonian parameters matching well with the single crystal values of 153 K. Powder spectrum at 77 K has been simulated, which agrees with the experimental one. The spin-lattice relation times are measured from the line width of the resonance lines recorded at different temperature.