Synthesis and spectral studies of cadmium(II) complexes derived from di-2-pyridyl ketone and N-phenylsemicarbazide: First structural report of a cadmium(II) complex of semicarbazone

A new semicarbazone (HL) based on di-2-pyridyl ketone and its three cadmium(II) complexes [CdL(CH₃COO)]₂ · 2CH₃OH (1), Cd(HL)Br₂ (2) and [Cd₂L₂N₃]₂ · H₂O (3) were synthesized and characterized by different physicochemical techniques. The complex, [CdL(CH₃COO)]₂ · 2CH₃OH (1) is having a dimeric structure. In complexes 1 and 3, the ligand moieties are coordinated as monoanionic (L⁻) forms and in complex 2, the ligand is coordinated as neutral (HL) one. The coordination geometry around cadmium(II) in 1 is distorted octahedral, as obtained by X-ray diffraction studies.     

A modern approach for the sensing of aqueous Al(III) ion by Ni(II) Salen‐type Schiff base complexes

In this work, we explore a modern concept of transmetalation (metal exchange) for the effective recognition of aqueous Al(III) ion. Three different Ni(II) salen‐type Schiff base complexes with different spacer diimine groups were prepared for the metal exchange reaction. These probes recognize Al(III) both colorimetically as well as fluorimetrically. The efficiency in sensing is mainly due to the low emission characteristics of the respective Ni(II) complexes which results in enhanced emission on the formation of Al(III) complex. The geometry of the central Ni(II) metal ion in the probe plays a pivotal role in the sensing action with the highest sensitivity being shown by the Ni(II) metal center with distorted square pyramidal geometry. Further DFT calculations and the energetics involved in the sensing mechanism via the formation of Al(III) complexes substantiates the experimental results.     

Siderophore-Mediated Iron Uptake Promotes Yeast–Bacterial Symbiosis

In the present study, siderophore produced by the marine yeast Aureobasidium pullulans was characterized as hydroxamate by chemical and bioassays. The hydroxamate assignment was supported by the appearance of peaks at 1,647.21?C1,625.99?cm^?1 and at 1,435.04?cm^?1 in the infrared spectrum. The purified siderophore exhibited specific growth-promoting activity under iron-limited conditions for siderophore auxotrophic probiotic bacteria. Cross-utilization of siderophore indicates a symbiotic relationship between the yeast A. pullulans and the selected probiotic bacterial strains. Statistical optimization of medium components for improved siderophore production in A. pullulans was depicted by response surface methodology. The shift in UV?CVis spectroscopy indicates the photoreactive property and subsequent oxidative cleavage of purified siderophore on exposure to sunlight.     

Manganese(II) complexes of substituted di-2-pyridyl ketone thiosemicarbazones: structural and spectral studies

The reaction between manganese(II) acetate and two substituted thiosemicarbazones derived from di-2-pyridyl ketone (HL) in 1:2 molar ratio produces new complexes of general formula [MnL2]. The thiosemicarbazone moiety in HL deprotonates and gets coordinated to Mn(II) through the azomethine nitrogen, one of the pyridyl nitrogens, and the thiolate sulfur in both the complexes. The crystal structure of [MnL2(1)] was established by single crystal X-ray diffraction and the compound crystallizes into a monoclinic lattice with P2(1)/c space group. Manganese(II) exists in a distorted octahedral geometry in the complexes.     

Investigation of QCM Sensors with Azobenzene Functionalized Coatings for the Detection of Nitroaromatics

Quartz Crystal Microbalance (QCM) based sensors have been used extensively to detect trace amounts of organic chemical vapors. These devices typically incorporate a polymer coating as an active layer that can bind the analytes of interest. Analyte adsorption causes a shift in the resonant frequency of the device proportional to the amount of adsorbed material. Currently some of the polymer coatings used in these sensors utilize hydrogen bonding to adsorb analytes. Dipole-dipole type interactions can also be utilized to promote interaction of the analytes with the polymer coating. Polymer coating containing segments that have a permanent molecular dipole can interact with explosive taggants. In this study, novel polypropylene glycol based polymers that incorporate both hydrogen bonding moieties and segments having large permanent dipole moment (p-nitroazobenzene functional groups) were synthesized and tested. The precursor polymer was prepared by the polymerization of the diglycidyl ether end functionalized polypropylene glycol macromer and aniline. The precursor polymers were post functionalized by an azo-coupling reaction. The sensor response to saturated vapors of o-nitrotoluene, nitrobenzene and 2,4 dinitrotoluene (DNT) saturated vapors was evaluated. Incorporation of p-nitroazobenzene moieties in the polymer increased the sensitivity of detection of the analytes. These studies offer new possibilities for using combination of interactions to improve the sensitivity of the QCM based sensors in the detection of nitroaromatic materials.     

Flux line lattice symmetries in the borocarbide superconductor LuNi2B2C

We compare the results of small angle neutron scattering on the flux line lattice (FLL) obtained in the borocarbide superconductor LuNi₂B₂C with the applied field along the c- and a-axes. For H‖c the temperature dependence of the FLL structural phase transition from square to hexagonal symmetry was investigated. Above 10 K the transition onset field. H ₂(T), rises sharply, bending away from H _c2(T) in contradiction to theoretical predictions of the two merging. For H‖a a first order FLL reorientation transition is observed at H _tr=3–3.5 kOe. Below H _tr the FLL nearest neighbor direction is parallel to the b-axis, and above H _tr to the c-axis. This transition cannot be explained using nonlocal corrections to the London model.     

Synthesis,spectral and structural studies of oxovanadium(IV/V) complexes derived from 2-hydroxyacetophenone-3-hydroxy-2-naphthoylhydrazone: polymorphs of oxovanadium(V) complex [VOL(OCH<Subscript>3</Subscript>)]

Abstract  

Oxovanadium(IV/V) complexes of 2-hydroxyacetophenone-3-hydroxy-2-naphthoylhydrazone (H₂L) have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, electronic and EPR spectra. The oxovanadium(V) complex [VOL(OCH₃)] is crystallized in two polymorphic forms, denoted by 1a and 1b, with space groups Pn2₁a and P_[`1] P_{{\bar{1}}} , respectively. Both have distorted square pyramidal structures.     

Development of a superconducting LINAC booster for the pelletron at mumbai

A superconducting linear accelerator (LINAC) to boost the energy of the heavy ion beams from the 14 UD pelletron accelerator at Mumbai is under development. The booster is based on quarter wave resonators (QWR) coated with lead which is superconducting at liquid helium temperature. The operating frequency is 150 MHz. Four resonators each are mounted in a cryostat module built indigenously. A total of seven such modules arranged in two arms with an isochronous and achromatic beam bend in the middle comprises the full LINAC. The transverse focusing of the beam through the LINAC is carried out using periodic quadrupole doublet magnets operating at room temperature. The present status of the project is described.     

Investigations of Ar+ implantation and proton irradiation of amorphous Fe40Ni40B20 samples by Mössbauer techniques

The effect of the implantation of 150 keV Ar⁺ ions at different doses on the surface of amorphous Fe₄₀Ni₄₀B₂₀ and the changes in the bulk properties following proton irradiations are investigated by conversion electron and transmission Mössbauer spectroscopy respectively. In the former case a correlation between the total Mössbauer absorption and the total energy deposited by incident Ar⁺ ions is established, indicating the development of certain stresses in the material, affecting the inter and intra molecular bonding in the near surface region. On the other hand, the proton irradiation seems to cause a reorientation of the atomic spins and also the formation of an additional Fe or Fe?Ni rich phase in the sample. Also the low field A.C. susceptibility is found to decrease as a function of the dose of incident protons. Possible reasons for the above behaviour are discussed.     

On the role of polarizability in chemical-biological interactions

This report considers the importance of electronic effects in their role in the QSAR of chemical-biological interactions. The problem of accounting for polarizability effects in ligand-substrate interactions is discussed in terms of molecular polarizability (MR) and NVE (number of valence electrons) using additive values for valence electrons. The two approaches give essentially the same result in examples of frog nerve toxicity and examples of nerve toxicity with rabbits and cockroaches. The point is made that no matter how one approaches QSAR, electronic interactions must be considered if we are to begin to develop a science of chemical-biological interactions.