Metal complexes of biological active 2-aminothiazole derived ligands

The most imperative outcomes of extensive sterdies (synthesis, spectral, structural characterization and biological applications) of metal complexes with thiazole derived ligands are reviewed. A large number of coordination compounds are known but still there is a need of new compounds to develop various efforts in different fields for biomedical applications. The synthesis of Schiff base ligands is very important, and it has recently drawn the attention of numerous research groups, making this area constantly evolve. Authors are also synthesizing some novel biologically potent ligands and their unique complexes and complexes found more biological active agents than that of ligands against bacteria, fungi and herbs. Highlights: Schiff bases and their metal chelates catalyze reactions; Schiff bases derived from sulfane thiadiazole show toxicities against insects; Schiff bases of thiadiazole have good plant regulator activity; Phenyl ring attached to the thiazole group showed interesting structure activity.     

Slow motion of a sphere away from a wall: Effect of surface roughness on the viscous force

An asymptotic analysis is given for the effect of roughness exhibited through the slip parameter β on the motion of the sphere, moving away from a plane surface with velocityV. The method replaces the no-slip condition at the rough surface by slip condition and employs the method of inner and outer regions on the sphere surface. For β > 0, we have the classical slip boundary condition and the results of the paper are then of interest in the microprocessor industry.     

EPR and optical study of Mn2+ doped ammonium tartrate single crystals

EPR study of Mn2+ doped ammonium tartrate single crystals is carried out at room temperature. The spin Hamiltonian parameters are: gx=1.9225+/-0.0002, gy=1.9554+/-0.0002, gz=2.1258+/-0.0002, A=(78+/-2) x 10(-4) cm(-1), B=(75+/-2) x 10(-4) cm(-1), D=(191+/-2) x 10(-4) cm(-1), E=(61+/-2) x 10(-4) cm(-1) and a=(22+/-1) x 10(-4) cm(-1) for site I and gx=1.9235+/-0.0002, gy=1.9574+/-0.0002, gz=2.0664+/-0.0002, A=(78+/-2) x 10(-4) cm(-1), B=(75+/-2) x 10(-4) cm(-1), D=(180+/-2) x 10(-4) cm(-1), E=(57+/-2) x 10(-4) cm(-1) and a=(22+/-1) x 10(-4) cm(-1) for site II, respectively. The observed optical bands are fitted with inter-electronic repulsion parameters (B and C), crystal field parameter (Dq) and Trees correction (alpha) and the values found are B=752, C=2438, Dq=765 and alpha=76 cm(-1). The data obtained are further used to discuss the surrounding crystal field and the nature of metal-ligand bonding in the crystal.     

Crystal and molecular structure of 5-trifluorothymine, a metabolite from human urine: Role of fluorine in stacking and hydrogen bonded interactions

The crystal structure of the metabolite from urine, 5-trifluorothymine [5F₃T] has been determined by single crystal X-ray diffractometric methods. Crystals of 5F₃T are monoclinic, space group P2₁/c with cell dimensions a = 6.7468(2), b = 15.0740(6), c = 13.4405(6), β = 90.412(2), V = 1366.88(8), Z = 8 (two molecules per asymmetric unit). Crystal structure of 5F₃T was determined with 3039 independent data and refined by full-matrix least squares methods to a final reliability factor of 0.047. Molecules of 5F₃T are connected by dimeric type of NH?O hydrogen bonding linking molecules related by a center of inversion into an extensive layer of dimeric molecules. These layers are stacked on top of each other at a stacking distance of 3.280 Å with a head-to-head stacking of the fluorine atoms on top of each other with no hydrogen bonding involving the fluorine atoms.     

汉语特色新词语及其英译问题探析

通过阐述汉语特色新词语的概念界定、主要特点和分类构成,梳理并探析了国内外在汉语特色新词语英译研究领域所取得的成就和存在的问题。在此基础上,有针对性地给出了汉语特色新词语准确英译的一些翻译策略和实用技巧。     

RP-HPLC-DAD method for the identification of two potential antioxidant agents namely verminoside and 1-O-(E)-caffeoyl-β-gentiobiose from Spathodea campanulata leaves

A simple and reliable high-performance liquid chromatographic method was successfully developed for the study of fingerprint chromatograms of extract and fractions from the leaves of Spathodea campanulata (SC) using verminoside (1) and 1-O-(E)-caffeoyl-β-gentiobiose (2) as marker compounds. Antioxidant activity of SC was determined by using free radical of 2,2-diphenyl-1-picryl-hydrazyl-hydrate as an experimental model. The docking study of selected target, tyrosinase and ligands (ascorbic acid, compounds 1 and 2) was performed through Autodock Vina v0.8. Fingerprints of methanol, chloroform, ethylacetate, n-butanol and water extracts could resolve 13, 11, 22, 16 and 5 peaks, respectively. Extract, fractions and compounds 1 and 2 previously isolated from SC displayed remarkable antioxidant activity with radical-scavenging activity ranging from 2.5 to 6.7 μg/mL. In silico study identified compounds 1 and 2 as potential inhibitors of tyrosinase correlating with the observed antioxidant activity in vitro.     

Synthesis and antioxidant activity study of carbothioamide and their corresponding thiazole derivatives

A novel series of 5-(p-(prop-2-ynyloxy)phenyl)-3-aryl-4,5-dihydropyrazole-1-carbothioamides 2a-f and functionalized 2-(3-(aryl)-5-(4-(prop-2-ynyloxy)phenyl)-4,5-dihydropyrazol-1-yl)-4-(3-arylsydnone-4-yl)thiazoles 4a-l were synthesized. The newly synthesized compounds were elucidated by analytical and spectral analysis. From the single-crystal X-ray diffraction method, it was observed that 2d crystallizes in a monoclinic crystal system with P21/n space group. The compounds 2d crystallized with cell parameters a = 15.0614 (19) Å, b = 6.0805 (7) Å, c = 20.903 (7) Å, α = 114.136 (6)^o, β = 110.709 (14) ^o, γ = 96.553 (5) ^o, V = 1790.6 (4) ų, Z = 4. From the Hirshfeld surface computational method, the major intercontacts present in these molecules are H…H (31.6%), C…H (18.2%) and S…H (12.2%), respectively. The newly synthesized compounds were tested for their ability to bleach 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical using DPPH scavenging assay. Among the synthesized compounds carbothioamide compounds 2c (90.7%) and 2b (89.8%) exhibited good DPPH scavenging activity compared to the rest of the compounds. Most of the synthesized carbothioamide molecules ( 2a-f ) found to be potent compared to the thiazole derivatives ( 4a-l ).     

Domino ring-opening metathesis-ring-closing metathesis of bicyclo[2.2.2]octene derivatives: scope and limitations

Domino metathesis involving ring-opening metathesis-ring-closing metathesis (ROM-RCM) of a bicyclo[2.2.2]octene derivative having an appropriate alkene chain, expected to produce a 7/6 fused bicyclic system, provided a decalin system in contrast to ROM-RCM of the corresponding bicyclo[2.2.1]heptene analogues, which as expected produced the 7/5 fused bicycles. The expected 6/7 bicyclic system could, however, be made through RCM of the elusive ROM product prepared from the same bicyclo[2.2.2]octene analogue by a nonmetathetic route. A rationale to explain the difference in reactivity pattern between these two systems toward ROM-RCM has been forwarded.     

Laser-Induced Breakdown Spectroscopy: An Approach to Detect Adulteration in Turmeric

In the present paper, four turmeric samples, A, B, C, and D, were analyzed using the laser-induced breakdown spectroscopic (LIBS) technique. Laser-induced breakdown spectra of A, B, and C give the spectral lines of elements such as carbon, sodium, potassium, magnesium, calcium, iron, and molecular bands of CN, whereas spectral signatures of the toxic elements lead and chromium are also present in sample D, demonstrating the adulteration in it. Principal component analysis of the LIBS data of the turmeric samples has been used for instant discrimination. The plots and principal components provide clusters belonging to two groups, enabling laser-induced breakdown spectroscopic data along with principal component analysis to be used as an instant monitoring tool.