EPR, IR and electronic spectral studies on Mn(II), Co(II), Ni(II) and Cu(II) complexes with a new 22-membered azamacrocyclic [N4] ligand

The complexes of transition metal ions with an azamacrocyclic tetradentate nitrogen donor [N4] ligand viz. 2,6,12,16,21,22-hexaaza;3,5,13,15-tetramethyltricyclo[15.3.1.1(7-11)] docosa;1(21),2,5,7,9,11(22),12,15,17,19-decaene (L) have been synthesized. All the complexes were found to have general composition M(L)X2 [where M = manganese(II), cobalt(II), nickel(II) and copper(II) and X = Cl- & NO3-]. All the complexes are characterized by the elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, 1H NMR, IR, electronic, EPR spectral and cyclic voltammetric studies. An octahedral geometry was assigned for Mn(II), Co(II) and Ni(II) complexes and tetragonal for Cu(II) complexes. The biological actions of the ligand and complexes have been screened in vitro against many bacteria and pathogenic fungi to study their comparative capacity to inhibit the growth.     

EPR and electronic spectral studies on Co(II), Ni(II) and Cu(II) complexes with a new tetradentate [N4] macrocyclic ligand and their biological activity

Cobalt(II), nickel(II) and copper(II) complexes having the general composition M(L)X2 (where M = CO(II), Ni(II) and Cu(II), L = ligand, i.e. 3,4,12,13-tetraketo-2,5,11,14,19,20-hexaazatricyclo[13.3.1.1(6-10)]cosane; 1(19),6,8,10(20),15,17-hexaene and X stands for Cl-; NO3- and SO42-), have been prepared. The structure of the complexes has been elucidated by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, electronic and EPR spectral studies. The magnetic moment measurements of the complexes indicate that the metal ion is in high-spin state. On the basis of IR, electronic and EPR spectral studies an octahedral geometry was assigned for Co(II) and Ni(II) complexes whereas tetragonal geometry for Cu(II) complexes. This ligand and its complexes were also screened against bacteria and pathogenic fungi in vitro.     

Correlation between metabolite ratios and ADC values of prostate in men with increased PSA level

Proton magnetic resonance spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI) were carried out in men with increased prostate-specific antigen (PSA) level. Forty subjects [controls (Group I) and patients (Groups II and III with PSA >20 and 4-20 ng/ml, respectively)] were investigated using endorectal coil at 1.5 T prior to transrectal ultrasound (TRUS)-guided biopsy. Metabolite ratio [citrate/(choline+creatine)] and apparent diffusion coefficient (ADC) were calculated for identical voxels. In patients, voxels that showed lower metabolite ratio showed reduced ADC in the peripheral zone (PZ) of the prostate, and voxels with increased metabolite ratio showed higher ADC. Metabolite ratios were used to predict areas of malignancy if the ratio was <1.4 and if ADC value was <1.17 x 10(-3) mm(2)/s. Patients in Group II had lower metabolite ratio and ADC in the PZ compared to controls and Group III. All 13 were positive for malignancy in MR, while 12 of 13 were positive on TRUS-guided sextant biopsy. In Group III, certain voxels of PZ that showed reduced metabolite ratio also showed lower ADC. A positive correlation was observed between metabolite ratio and ADC. MR predicted areas of malignancy in PZ in 15 of 20 patients; however, only six were positive on TRUS-guided biopsy perhaps due to high false-negative rate of TRUS-guided biopsy. Results show positive correlation between MRSI and DWI and their potential in detection of malignancy, thereby improving the diagnosis especially in patients with PSA level of 4-20 ng/ml.     

Studies on polymorphic modifications of copper phthalocyanine

Four α-, β-, γ- and ε-polymorphic forms of copper phthalocyanine are synthesized. They are characterized and their properties are compared based on the IR spectral measurements in the finger print region, magnetic susceptibility measurements, ESR study, powder X-ray diffraction and electrical conductivity studies. The data support the existence of all the four polymorphic forms. All the forms are having the monoclinic structure with different crystal lattice constants. The electrical conductivity study in air from 25°C to 200°C for all the four polymorphic modifications are done and their differences may be accounted for difference in interplanar spacing, molecular orientations, intermolecular interactions and mobilities of the charge carriers.     

K-K electron capture from adenine and CO2 molecule by fast carbon ions using KLL-Auger electron technique

The experimental measurement of total electron transfer cross section in Bragg peak energy region is important to understand energy loss in the biomolecular system. In this study, we have measured state selective, K-K electron capture and K-ionization cross sections for adenine (C ₅H ₅N ₅) in collisions with fast (2.5–5 MeV/u) C ions. These are compared with the data for smaller gas molecule, CO ₂. These are derived from a study of the KLL-Auger electron emission yields as a function projectile charge state. The K-ionization cross-section (σ_KI) data are compared with the ECUSAR (united and separated atom [USA] approximation with energy loss [E], Coulomb deflection [C], and relativistic [R] corrections) model calculation. The measured σ_KI data and the calculations are in good agreement. The K-K transfer cross-section (σ_K−K) data are compared with the CPSSR (perturbed stationary state [PSS] with Coulomb deflection [C] and relativistic corrections [R]) calculation that underestimates the measured data for such symmetric collision system. The energy dependence of σ_K−K for adenine is found to be flat in contrast to a sharp variation predicted by the model. The K-transfer cross section is found to be substantial fraction of the K-ionization.     

Studies on phthalocyanine sheet polymers

Cobalt, nickel and copper phthalocyanine sheet polymers are synthesized by heating their respective metal (II) phthalocyanine tetracarboxylic acids at 400 °C in nitrogen atmosphere. These polymers are characterized using UV-Visible spectra, IR spectra, magnetic susceptibility, X-ray powder diffraction and thermogravimetric analysis. Electrical conductivity studies are carried out using two-probe technique in the temperature range 25-200 °C for each polymer. These polymeric materials showed room temperature electrical conductivity 10-1000 times higher values compared to earlier reported values for this type of sheet polymers.     

Elusive Zintl Ions [μ‐HSi4]3− and [Si5]2− in Liquid Ammonia: Protonation States,Sites, and Bonding Situation Evaluated by NMR and Theory

The existence of [μ‐HSi₄]^3? in liquid ammonia solutions is confirmed by ¹H and ²⁹Si NMR experiments. Both NMR and quantum chemical calculations reveal that the H atom bridges two Si atoms of the [Si₄]^4? cluster, contrary to the expectation that it is located at one vertex Si of the tetrahedron. The calculations also indicate that in the formation of [μ‐HSi₄]^3?, protonation is driven by a high charge density and an increase of electron delocalization compared to [Si₄]^4?. Additionally, [Si₅]^2? was detected for the first time and characterized by NMR. Calculations show that it is resistant to protonation, owing to a strong charge delocalization, which is significantly reduced upon protonation. Thus, our methods reveal three silicides in liquid ammonia: unprotonated [Si₅]^2?, terminally protonated [HSi₉]^3?, and bridge‐protonated [μ‐HSi₄]^3?. The protonation trend can be roughly predicted by the difference in charge delocalization between the parent compound and the product, which can be finely tuned by the presence of counter ions in solution.     

A high resolution X-ray crystal spectrometer to study electron and heavy-ion impact atomic collisions

We have studied fast ion-atom and electron-atom collision processes using a reconditioned high resolution X-ray spectrometer. The X-rays, generated by the collisions, are dispersed by a curved ADP crystal (Johansson geometry) and detected by a gas proportional counter. A self-written LabVIEW based program has been used to give precise and controlled movement to the crystal and for data acquisition. The performance was tested by detecting the Kα diagram and satellite lines of several elements. The Kα satellite lines of Al have been studied in collision with 3–12 keV electrons and 40 MeV C⁴⁺ ions. In ion collisions as large as four L-vacancies are created simultaneously with the K-vacancy, compared to two satellites in case of the e-impact. In addition, we have measured the X-rays from H-, He- and Li-like Si ions which arise due to the electron loss/capture process in highly charged 80 MeV Si⁷⁺ ions in collision with thin carbon foil. Approximate charge state distribution has been obtained using this new technique.      

Bianchi Type I String Dust Magnetized Cosmological Models in Lyra Geometry

Bianchi type I string dust cosmological models in the presence and absence of magnetic field in the frame work of Lyra geometry are investigated. To get the deterministic model of the universe, we assume that the eigenvalue （σ^11） of shear tensor （σ^ii） is proportional to expansion （θ）. This leads to A = （BC）^n, where A, B, C are metric potentials and n is a constant. To discuss the results in terms of cosmic time t, we have considered n = 1. The physical and geometrical aspects＇ of the models and singularities in the models are also discussed.