Cobalt and manganese nets via their wires: facile transformation in metal-diorganophosphates

The manganese and cobalt complexes [M(dtbp)2]n (M=Mn, Co; dtbp=di-tert-butyl phosphate), which exist as one-dimensional molecular wires, transform to [M(dtbp)2(bpy)2.2H2O]n by the addition of 4,4-bipyridine (bpy) at room temperature; the latter compounds form noninterpenetrating rectangular grid structures.     

Non-interpenetrating transition metal diorganophosphate 2-dimensional rectangular grids from their 1-dimensional wires: structural transformations under mild conditions

The manganese, cobalt, and cadmium complexes [M(dtbp)2]n (M = Mn (1) and Co 2) and [Cd(dtbp)2(H2O)]n (3) (dtbp = di-tert-butyl phosphate), which exist as one-dimensional molecular wires, transform to non-interpenetrating rectangular grids [M(dtbp)2(bpy)2.2H2O]n (M = Mn (4), Co (5), and Cd (6)) by the addition of 4,4-bipyridine (bpy) at room temperature. Products 4-6 have also been prepared by a room-temperature reaction or by solvothermal synthesis in methanol through a direct reaction between the metal acetate, di-tert-butyl phosphate, and 4,4'-bipyridine (bpy) in a 1:2:2 molar ratio. Single-crystal X-ray structure determination of 4-6 shows that these compounds are composed of octahedral transition metal ions woven into a two-dimensional grid structure with the help of bpy spacer ligands. The axial coordination sites at the metal are occupied by bulky unidentate dtbp ligands, which prevent any interpenetration of the individual grids. The change of reaction conditions from solvothermal to hydrothermal, for the attempted synthesis of a magnesium grid structure, however leads to the isolation of an organic phosphate [(H2bpy)(H2PO4)2] (7) and an inorganic phosphate [Mg(HPO4)(OH2)3] (8). Compound 7 can also be prepared quantitatively from a direct reaction between bpy and H3PO4. The new organic phosphate 7 is a unique example of a phosphate material with alternating layers of [H2bpy]2+ cations and [H2PO4]- anions that are held together by hydrogen bonds. Solid-state thermal decomposition of 4-6 produced the respective metaphosphate materials [M(PO3)2] (M = Mn (9), Co (10), and Cd (11)). All new metal-organic phosphates have been characterized by elemental analysis, thermal analysis (TGA, DTA, DSC), and IR and NMR spectroscopy. The metaphosphate ceramic materials were characterized by IR spectral and powder X-ray diffraction studies.     

Analysis on air suspended particles of Coimbatore — a FTIR study

An infrared absorption method has been used to identify the minerals in dust collected from some parts of Coimbatore, Coimbatore district, Tamil Nadu without grinding. The KBr pellet technique was employed. The results obtained from the IR spectra show the presence of quartz, asbestos, kaolinite, calcite, haematite, montmorllonite, nacrite and coal. The hazardous effect of inhalation of these minerals are explained. The results show Pollachi main road is more contaminated with hazardous minerals.     

Silver nanoparticles embedded in amine-functionalized silicate sol–gel network assembly for sensing cysteine,adenosine and NADH

Silver nanoparticles embedded in amine-functionalized silicate sol–gel network were synthesized and used for sensing biomolecules such as cysteine, adenosine, and β-nicotinamide adenine dinucleotide (NADH). The sensing of these biomolecules by the assembly of silver nanoparticles was triggered by the optical response of the surface plasmon resonance (SPR) of the silver nanoparticles. The optical sensor exhibited the lowest detection limit (LOD) of 5, 20, and 5 μM for cysteine, adenosine, and NADH, respectively. The sensing of biomolecules in the micromolar range by using the amine-functionalized silicate sol–gel embedded silver nanoparticles was studied in the presence of interference molecules like uridine, glycine, guanine, and guanosine. Thus, the present approach might open up a new avenue for the development of silver nanoparticles-based optical sensor devices for biomolecules.     

A 3-V electrochemical capacitor study based on a magnesium polymer gel electrolyte by three different carbon materials

An organic medium with lithium and sodium salts is not so safe in some cases. Structural features of carbon electrodes play a vital role on the capacitor parameters. Based on that above said, we have studied three kinds of supercapacitors using a gel electrolyte from 0.5 M of magnesium imide salt–polyethylene oxide (PEO) in propylene carbonate (PC). The cell electrodes were carbide derived carbon (CDC), PICACTIF and YECA activated carbons. The gel component interactions were viewed by infrared spectroscopy. The cell reversibility and symmetric were analyzed using cyclic voltammetry (CV) technique. Linear sweep voltammetry (LSV) technique was taken to approximate the electrolyte stability. Electrochemical impedance spectroscopy (EIS) result reflects the resistance and capacitive behavior of the cells, i.e., The YECA carbon shows a good capacitive behavior over the CDC- and PICACTIF-based cells whereas the CDC cell has shown a low resistance. Galvanostatic charge-discharge study (CD) results have shown a stable and ideal 2.5-V capacitor behavior. The capacitors have also proven an obtainable good specific capacitance, real power, and real energy density of ~25 F g^?1, 0.7 kW kg^?1, and 25 W·h kg^?1, respectively. Moreover, the cells were tested for 3-V limit.     

Metastable zonewidth, induction period and interfacial energy of zinc tris(thiourea) sulfate

Metastable zonewidth and induction period measurements on ZTS and ZTSP crystals are presented. The effect of pH on the solubility, metastable zonewidth and induction period has been studied. The effect of substitution of phosphate on the nucleation parameters has been presented. The interfacial energy for pure and phosphate mixed ZTS solutions at 30°C has also been estimated. There is a significant variation in the induction period and interfacial energy due to decrease in solution pH and phosphate substitution.     

Influence of alkali metal sodium doping on the properties of potassium hydrogen phthalate (KHP) crystals

The effect of doping sodium on the growth process and properties of potassium hydrogen phthalate (KHP) single crystals by slow evaporation solution growth technique has been investigated. Incorporation of sodium into the crystalline matrix even in the presence of low dopant concentration in aqueous growth medium is well confirmed by energy dispersive X-ray spectroscopy and quantified by atomic absorption spectroscopy and inductively coupled plasma emission spectrometer (ICP) techniques. The FT-IR spectral analysis confirms the slight distortion of the structure of the crystals as a result of doping. The TG-DTA studies reveal the purity of the material and no decomposition is observed up to the melting point. Low Na-doping (10 mol%) slightly increases the second harmonic generation efficiency, whereas heavy doping {[KHP]:[Na] = 1:1} results in significant enhancement. It has also been found that the doping results in morphological changes.     

Synthesis of some monocyclic‐N‐acetyl 4′‐aza‐D‐nucleosides

1,2,3,5‐Tetra‐O‐acetyl‐4‐deoxy‐4‐(acetamido)‐β‐D‐ribofuranose 5 was prepared from L‐lyxose, which on condensation with silylated nucleoside bases gave the corresponding protected 4′‐azanucleosides. The protecting groups were removed using methanolic ammonia to afford the N‐acetyl‐4′‐azanucleosides, wherein the sugar ring oxygen is replaced with a substituted nitrogen atom, in good yields. Further, the 1‐(4‐deoxy‐4‐acetamido‐β‐D‐ribofuranosyl)thymine 16 was transformed to the corresponding 2′‐deoxy, 2′,3′‐dideoxy derivatives. The stereochemical assignments of the synthesized nucleosides were established based on NMR and X‐ray studies.