Determination of inorganic nitrate impurity from nicorandil and its tablet dosage form by simple reversed phase liquid chromatographic method

A simple, fast, precise, specific and economical reverse phase liquid chromatographic method was developed for determination of nitrate (NIT) impurity from nicorandil (NIC) and its tablet dosage form. NIT is process impurity as well as a degradation product of NIC. This article is based on application of amino propyl silane (APS) column for determination of NIT in presence of NIC and various excipients using potassium nitrate as a standard. The developed method was validated for its intended use by evaluating various important parameters like linearity, accuracy, recovery and specificity. The developed method was applied to evaluate the compatibility study of NIC with various excipients by monitoring the NIT content.     

Elastomeric polypeptide-based biomaterials

Elastomeric proteins are characterized by their large extensibility before rupture, reversible deformation without loss of energy, and high resilience upon stretching. Motivated by their unique mechanical properties, there has been tremendous research in understanding and manipulating elastomeric polypeptides, with most work conducted on the elastins but more recent work on an expanded set of polypeptide elastomers. Facilitated by biosynthetic strategies, it has been possible to manipulate the physical properties, conformation, and mechanical properties of these materials. Detailed understanding of the roles and organization of the natural structural proteins has permitted the design of elastomeric materials with engineered properties, and has thus expanded the scope of applications from elucidation of the mechanisms of elasticity to the development of advanced drug delivery systems and tissue engineering substrates.     

Purification and Characterization of Enterocin LR/6, a Bacteriocin from <Emphasis Type=Italic>Enterococcus faecium</Emphasis> LR/6

Enterocin LR/6, a bacteriocin obtained from the culture filtrate of Enterococcus faecium strain LR/6, has been purified to homogeneity using ammonium sulfate precipitation, cation-exchange chromatography, gel-filtration, and checked on reverse-phase high-performance liquid chromatography. It is active at high temperatures (boiling as well as autoclaving) and over a wide range of pH (2.0–8.0). Also, it is sensitive to a number of proteolytic enzymes but is stable in the presence of surfactants and organic solvents. The protein could be stored at least up to 1 year at low temperatures (4 °C and −20 °C) without any loss of activity. The N-terminal sequence of enterocin LR/6 showed no homology with known enterocins or other bacteriocins present in the database, suggesting it to be a novel enterocin. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry and tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed its mass to be ∼6.1 kDa. It showed a bactericidal mode of action against indicator strain, Micrococcus luteus.     

Preparation of highly crystalline blue emitting MVO4:Tm (M=Gd, Y) spherical nanoparticles: Effects of activator concentration and annealing temperature on luminescence, lifetime and quantum yield

Highly crystalline spherical nanoparticles of MVO₄:Tm³⁺ (M=Gd, Y) having a size of 20–45 nm were prepared using ethylene glycol as both capping agent and reaction medium. X-ray diffraction study shows linear decrease in the unit cell volume with an increase in Tm³⁺ concentrations in MVO₄ (M=Gd, Y; Tm³⁺=0, 2, 5, 7, 10, 15, 20, 40, 60, 80 and 100 at%), indicative of quantitative substitution of Gd³⁺/Y³⁺ lattice sites by Tm³⁺ ions in MVO₄. Blue light emission at 475 nm is observed after excitation at 310 nm due to energy transfer from VO₄³⁻ absorption band to Tm³⁺. Emission intensity and average decay lifetime increase with an increase in heat treatment from 500 to 900 °C. This has been attributed to an extent of reduction in non-radiative process arising from surface. The emission intensity of Tm³⁺ in GdVO₄ host is higher than that in YVO₄ and thus the former host is better. Quantum yield increases with increase in heat-treatment temperature. This material will be the alternative blue light emitter.     

New Dual Donor–Acceptor (2D‐π‐2A) Porphyrin Sensitizers for Stable and Cost‐Effective Dye‐Sensitized Solar Cells

A series of porphyrin sensitizers that featured two electron‐donating groups and dual anchoring groups that were connected through a porphine π‐bridging unit have been synthesized and successfully applied in dye‐sensitized solar cells (DSSCs). The presence of electron‐donating groups had a significant influence on their spectroscopic, electrochemical, and photovoltaic properties. Overall, the dual anchoring groups gave tunable electronic properties and stronger attachment to TiO₂. These new dyes were readily synthesized in a minimum number of steps in gram‐scale quantities. Optical and electrochemical data confirmed the advantages of these dyes for use as sensitizers in DSSCs. Porphyrins with electron‐donating amino moieties provided improved charge separation and better charge‐injection efficiencies for the studied dual‐push–pull dyes. Attenuated total reflectance–Fourier‐transform infrared (ATR‐FTIR) and X‐ray photoelectron spectroscopy of the porphyrin dyes on TiO₂ suggest that both p‐carboxyphenyl groups are attached onto TiO₂, thereby resulting in strong attachment. Among these dyes, cis-Zn2BC2A , with two electron‐donating 3,6‐ditertbutyl‐phenyl‐carbazole groups and dual‐anchoring p‐carboxyphenyl groups, showed the highest efficiency of 4.07 %, with J_SC=9.81 mA cm^?2, V_OC=0.63 V, and FF=66 %. Our results also indicated a better photostability of the studied dual‐anchored sensitizers compared to their mono‐anchored analogues under identical conditions. These results provide insight into the developments of a new generation of high‐efficiency and thermally stable porphyrin sensitizers.     

Synthesis,mesomorphic, photophysical and computational studies of new achiral four-ring unsymmetrical bent-core mesogens and their Copper(II) complexes

New achiral four-ring unsymmetrical bent-core mesogens derived from 2,5-dihydroxybenzaldehyde and their copper(II) complexes have been synthesised as a new design with an imine and ester linkage. These new bent-core molecules resemble hockey-stick shape, which possesses 4-n-alkyloxy chain (4-n-hexyloxy and 4-n-decyloxy) at one end and methyl or methoxy group at the other end of the molecule. The synthesis, spectroscopic characterisation, phase transition temperature and characterisation of phase behaviour are reported. The bent-core molecules exhibited monotropic nematic and smectic A phase depending on the terminal chain length. Interestingly, copper(II) complexes of bent-core molecules displayed monotropic nematic phase. This is the first report on copper(II) complexes of bent-core molecules that exhibited nematic phase. The four-ring bent-core molecule exhibited fluorescence with large stoke shift. The density functional theory calculations of bent-core molecules and their copper(II) complexes are carried out using Gaussian 09 program at B3LYP level to obtain the stable molecular conformation, dipole moment, highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energies and bending angle of the compounds. The natural atomic charges and electronic configurations of the atoms of free ligands as well as the complexes have been evaluated.     

Volumetric Properties of Aqueous 2-Chloroethanol Solutions and Volumes of Transfer of Some Amino Acids and Peptides from Water to Aqueous 2-Chloroethanol Solutions

Densities and apparent molar volumes of aqueous 2-chloroethanol were determined at temperatures from 15.0 to 34.4°C using digital densimetry. The results of the volumetric measurements have been used to calculate the following thermodynamic quantites at 25°C: V ₂ ^o = 55.05 ± 0.02 cm³-mol^–1, (V ₂ ^o/T)_p = 0.01486 ± 0.00318 cm³-K^–1-mol^–1, and (² V ₂ ^o/T ²)_p = 0.02972 ± 0.00318 cm³-K^–2-mol^–1. Partial molar volumes of transfer from water to 1 mol-dm^–3 2-chloroethanol have also been determined for L-glycine, L-alanine, L-serine, L-glutamic acid, and L-aspartic acid at 35.0°C. The transfer results have been explained in terms of the nature of the interactions of the groups in the solute and solvent. Hydration numbers of L-glycine and L-alanine have also been calculated in aqueous 2-chloroethanol.     

Encapsulating Au‐Fe3O4 Nanodots into AIE‐active Supramolecular Assemblies: Ambient Visible‐light Harvesting “Dip‐Strip” Photocatalyst for C−C/C−N Bond Formation Reactions

The present study demonstrates the development of a supramolecular porous ensemble consisting of hetero‐oligophenylene derivative 6 and Au‐Fe₃O₄ nanodots. Supramolecular assemblies of AIE‐active hetero‐oligophenylene derivative 6 served as reactors for the generation of Au‐Fe₃O₄ nanodots. The as prepared supramolecular ensemble functioned as an efficient recyclable photocatalytic system for C(sp²)?H bond activation of anilines for the construction of quinoline carboxylates. Interestingly, the “dip catalyst” prepared by depositing PTh‐co‐PANI‐6: Au‐Fe₃O₄ nanodots on a filter paper served as a recyclable strip (up to 10 cycles) for C?C/C?N bond formation reaction.     

Triphenylene based copper ensemble for the detection of cyanide ions

The binding behavior of triphenylene based copper ensemble prepared in situ has been investigated toward various anions (F(-), Cl(-), Br(-), I(-), CH(3)COO(-), H(2)PO(4)(-), NO(3)(-), OH(-), ClO(4)(-), CN(-), CO(3)(-) and SO(4)(-)) by UV-vis and fluorescence spectroscopy. Among various anions tested, 1-Cu(2+) ensemble shows selective and sensitive response towards cyanide ions and responds to CN(-) ions even in the presence of bovine serum albumin and in blood serum milieu. Further, as practical application of compound 1, we utilized the TLC strips coated with THF solution of 1 for the solid state detection of copper and cyanide ions.     

One-pot synthesis of trichloromethyl carbinols from primary alcohols

Versatile trichloromethyl carbinols can be prepared in one pot from primary alcohols by treatment with Dess-Martin periodinane (DMP) in CHCl(3) followed by introduction of commercially available 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). A modification of the method was used to convert chiral primary alcohol (R)-(-)-2,2-dimethyl-1,3-dioxolane-4-methanol to the corresponding trichloromethyl carbinol with complete stereochemical fidelity, despite the reactant proceeding through a base-sensitive aldehyde intermediate.