The synthesis and ligand properties of the dihydro-bis-(1-indazolyl)borate anion

Summary Potassium dihydro-bis-(1-indazolyl)borate, synthesized from potassium borohydride and indazole, has been used as a reagent to yield complexes with copper(II), nickel(II), cobalt(II), manganese(II) and iron(III) ions. From i.r. spectral studies the ligand is uninegative and bidentate and coordination occurs through the nitrogen atom at position 2 of the indazole ring system in all cases. With the sole exception of the copper(II) complex, the nitrogen atom at position 1 is also involved in forming a bridge with an adjacent metal ion. On the basis of electronic spectral studies and magnetic susceptibility measurements a distorted square planar structure involving chlorine bridges has been proposed for the copper complex. An octahedral geometry with ligand bridges for all complexes is tentatively proposed and it appears that all are polymers.     

Matrix-assisted laser desorption/ionization mass spectrometry with re-engineered 2,5-dihydroxybenzoic acid derivative

Dihydroxybenzoic acid was modified to three analogues (M2, M4 and M6). The analogues exhibited specific properties that resulted in enhancement of analyte signal intensity with or without addition of iodine compared to the underivatized parent. Addition of iodine to M2, an ester of dihydroxybenzoic acid that had a terminal double bond in the alkyl chain, resulted in peak intensities comparable to the parent, indicating that iodine interaction across the double bond resulted in enhancement although the exact mechanism is not fully understood. No enhancement on addition of iodine was observed for M4, which had a long alkyl chain that contained no double bonds. The alkyl chain allowed micelle formation in solution, which in turn allowed more uniform analyte-to-matrix mixing. The final analogue combined the long alkyl chain of M4 with the double bond of M2 and exhibited either similar peak intensities to that of dihydroxybenzoic acid or better. Micelle formation in solution was examined using spectroscopy and in the solid by reflective microscopy. The standard deviation from spot to spot was considerably lower relative to dihydroxybenzoic acid (RSD 3.4%vs. 14.2%). Unlike dihydroxybenzoic acid, the novel matrix M6 was able to yield characteristic peaks for analytes such as ubiquitin.     

Interaction of Carrier Protein with Potential Metallic Drug Candidate N-Glycoside ‘GATPT’: Validation by Multi-Spectroscopic and Molecular Docking Approaches

Lysozyme is often used as a model protein to study interaction with drug molecules and to understand biological processes which help in illuminating the therapeutic effectiveness of the drug. In the present work, in vitro interaction studies of 1-{(2-hydroxyethyl)amino}-2-amino-1,2-dideoxy-d-glucose triphenyl tin (IV) (GATPT) complex with lysozyme were carried out by employing various biophysical methods such as absorption, fluorescence, and circular dichroism (CD) spectroscopies. The experimental results revealed efficient binding affinity of GATPT with lysozyme with intrinsic binding (K_b) and binding constant (K) values in the order of 10⁵ M⁻¹. The number of binding sites and thermodynamic parameters ΔG, ΔH, and ΔS at four different temperatures were also calculated and the interaction of GATPT with lysozyme was found to be enthalpy and entropy driven. The CD spectra revealed alterations in the population of α–helical content within the secondary structure of lysozyme in presence of GATPT complex. The morphological analysis of the complex with lysozyme and lysozyme-DNA condensates was carried out by employing confocal and SEM studies. Furthermore, the molecular docking studies confirmed the interaction of GATPT within the larger hydrophobic pocket of the lysozyme via several non-covalent interactions.     

Heat pipes: progress in thermal performance enhancement for microelectronics

Journal of Thermal Analysis and Calorimetry - The aim of this study is to oversee the impact of various techniques on thermal performance of heat pipes and to comprehensively cover the progress...     

Phytochemical Analysis,Pharmacological and Safety Evaluations of Halophytic Plant,Salsola cyclophylla

Salsola cyclophylla, an edible halophyte, is traditionally used for inflammation and pain. To confirm the claimed anti-inflammatory and analgesic properties, a detailed study on respective pharmacological actions was undertaken. The activities are contemplated to arise from its phytoconstituents. The LC-MS analysis of S. cyclophylla 95% aqueous-ethanolic extract revealed the presence of 52 compounds belonging to phenols, flavonoids, coumarins, and aliphatics class. A high concentration of Mn, Fe, and Zn was detected by atomic absorption spectroscopic analysis. The ethyl acetate extract showed the highest flavonoid contents (5.94 ± 0.04 mg/g, Quercetin Equivalents) and Fe2⁺-chelation (52%) potential with DPPH radicals-quenching IC₅₀ at 1.35 ± 0.16 mg/mL, while the aqueous ethanolic extract exhibited maximum phenolics contents (136.08 ± 0.12 mg/g, gallic acid equivalents) with DPPH scavenging potential at IC₅₀ 0.615 ± 0.06 mg/mL. Aqueous ethanolic extract and standard quercetin DPPH radicals scavenging’s were equal potent at 10 mg/mL concentrations. The aqueous ethanolic extract showed highest analgesic effect with pain reduction rates 89.86% (p = 0.03), 87.50% (p < 0.01), and 99.66% (p = 0.0004) after 60, 90, and 120 min, respectively. Additionally, aqueous ethanolic extract exhibited the highest anti-inflammation capacity at 41.07% (p < 0.0001), 34.51% (p < 0.0001), and 24.82% (p < 0.0001) after 2, 3, and 6 h of extract’s administration, respectively. The phytochemical constituents, significant anti-oxidant potential, remarkable analgesic, and anti-inflammatory bioactivities of extracts supported the traditionally claimed anti-inflammatory and analgesic plant activities.     

Computational analysis of entropy generation in mixed convection flow past a vertical wavy cone

Journal of Thermal Analysis and Calorimetry - The problem of entropy generation in mixed convection flow of incompressible viscous fluid along an isothermal vertical wavy cone is investigated...     

Two new proanthocyanidin trimers isolated from Cistus incanus L. demonstrate potent anti-inflammatory activity and selectivity to cyclooxygenase isoenzymes inhibition

Two new proanthocyanidin trimers have been isolated from Cistus incanus herb; gallocatechin-(4α→6)-gallocatechin-(4α→8)-gallocatechin (compound 1) and epigallocatechin-3-O-gallate-(4ß→8)-epigallocatechin-3-O-gallate-(4ß→8)-gallocatechin (compound 2). The structures were determined on the basis of 1D- and 2D-NMR (HSQC, HMBC) of their peracetylated derivatives, MALDI-TOF-MS and by acid-catalysed degradation with phloroglucinol. A more abundant proanthocyanidin oligomer was also isolated, purified and its chemical constitution studied by ¹³C-NMR and phloroglucinol degradation. The mean molecular weight of the polymer was estimated to be about 7 to 8 flavan-3-ol-units with a ratio of procyanidin?:?prodelphinidin units at 1:5, some of which are derivatised by gallic acid. Water extract and higher oligomeric proanthocyanidin fractions of C. incanus significantly inhibited TPA-induced oedema when applied topically at doses of 0.5 and 1 mg/ear in mice. Furthermore, the extracts and the pure compounds inhibited COX-1 and COX-2 activities. In addition, compound 2 exhibited an IC₅₀ of 4.5 μM against COX-2 indicating its high selectivity towards COX-2.     

纳米多级孔分子筛：简短的综述

分子筛是一种三维微孔结构的硅铝酸盐晶体,具有灵活多变的骨架和组成、较高的物理和水热稳定性、无毒、高比表面积、离子可交换性以及很低的成本等特点,因而在油品精制、石油化学、农业、水和污水处理等众多领域中用作离子交换剂、催化剂和吸附剂。尽管分子筛的应用是基于其本身的微孔结构,但微孔也导致体积较大的反应物和产物分子的传质阻力高。通过制备纳米尺度和多级孔结构的分子筛等多种手段可克服常规分子筛所具有的传质限制。人们已经开发了多种方法制备了新型的分子筛材料,并考察了它们在各种催化反应和吸附反应中的性能。在反应体系中采用这种多级孔的纳米分子筛,有可能提高催化剂的使用寿命和催化性能,抑制积碳和失活。本综述概述了多级孔分子筛和纳米分子筛的高性能及其合成方法的最新进展,讨论了每个合成方法的优缺点,简述了纳米分子筛和二级孔结构分子筛的催化应用,并与常规分子筛进行了比较。