Interesting periodic variations in physical and chemical properties of homonuclear diatomic molecules

We carry out a systematic study of various ground state and response properties of homonuclear diatomic molecules (from hydrogen to rubidium, including transition metals) as a function of atomic number of constituent atoms. We perform the ground state and response property calculations by using state of the art density functional theory/time dependent density functional theory. We observe that several properties of homonuclear diatomic molecules show periodic variations along rows and columns of the periodic table. The periodic variations in the ground state properties of diatomic molecules may be explained by the nature and type of the bond that exists between the constituent atoms. Similarly, the periodic variations in the response properties such as static dipole polarizability and strength of the van der Waals interaction between diatomic molecules have been correlated with the variations in metallic/nonmetallic character of the elements along the periodic table. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Design,Synthesis, Docking,DFT, MD Simulation Studies of a New Nicotinamide-Based Derivative: In Vitro Anticancer and VEGFR-2 Inhibitory Effects

A nicotinamide-based derivative was designed as an antiproliferative VEGFR-2 inhibitor with the key pharmacophoric features needed to interact with the VEGFR-2 catalytic pocket. The ability of the designed congener ((E)-N-(4-(1-(2-(4-benzamidobenzoyl)hydrazono)ethyl)phenyl)nicotinamide), compound 10, to bind with the VEGFR-2 enzyme was demonstrated by molecular docking studies. Furthermore, six various MD simulations studies established the excellent binding of compound 10 with VEGFR-2 over 100 ns, exhibiting optimum dynamics. MM-GBSA confirmed the proper binding with a total exact binding energy of −38.36 Kcal/Mol. MM-GBSA studies also revealed the crucial amino acids in the binding through the free binding energy decomposition and declared the interactions variation of compound 10 inside VEGFR-2 via the Protein–Ligand Interaction Profiler (PLIP). Being new, its molecular structure was optimized by DFT. The DFT studies also confirmed the binding mode of compound 10 with the VEGFR-2. ADMET (in silico) profiling indicated the examined compound’s acceptable range of drug-likeness. The designed compound was synthesized through the condensation of N-(4-(hydrazinecarbonyl)phenyl)benzamide with N-(4-acetylphenyl)nicotinamide, where the carbonyl group has been replaced by an imine group. The in-vitro studies were consonant with the obtained in silico results as compound 10 prohibited VEGFR-2 with an IC₅₀ value of 51 nM. Compound 10 also showed antiproliferative effects against MCF-7 and HCT 116 cancer cell lines with IC₅₀ values of 8.25 and 6.48 μM, revealing magnificent selectivity indexes of 12.89 and 16.41, respectively.     

Synthesis,Optoelectronic and Photoluminescent Characterizations of Green Luminous Heteroleptic Ternary Terbium Complexes

Journal of Fluorescence - This article presents four ternary terbium complexes based on fluorinated 2-thenoyltrifluoroacetone (TTFA) and N donor bidentate neutral ligands. The prepared complexes...     

EPR and NMR characterization of theS=9 excited state and spin density distribution in the single-molecule magnet Fe8Br8: Implications to theS=10 model and magnetization tunneling pathways

High-sensitivity, variable-frequency, high-field electron paramagnetic resonance (EPR) measurements and nuclear magnetic resonance (NMR) measurements are reported for theS=10 single-molecule magnet Fe₈Br₈. We find that theS=10 state is nested with its first excited state, withS=9, located at only 24±2 K above. Also reported are some preliminary⁸¹Br NMR measurements of the unpaired electron spin density on the Br^? sites. The results provide new insight and benchmarks for improved electronic and magnetic structural calculations and macroscopic tunneling pathways of this class of single-molecule magnets.     

Magic angle spinning NMR on single crystals as a new aid in characterizing phase transitions: application to squaric acid

Accurate measurement of δ_ISO, the isotropic part of the NMR chemical shift tensor, is usually difficult for solids. This study suggests that the technique of magic angle sample spinning (MAS), employing single crystals, might be suitable for this purpose. In our ¹³C CP(cross polarization)/MAS measurements on squaric acid (H₂C₄O₄), single crystals yielded about five-fold narrower line widths than powder samples. The resolution enhancement thus obtained enabled us to measure δ_ISO for all four carbons of squaric acid, and to show that the average O-H distance can serve as an order parameter for the phase transition at 373 K. Additionally, the ¹³C δ_ISO data suggest that the transition mechanism involves a significant displacive component, in addition to the known order-disorder behavior, thus demonstrating the high potential of the single crystal MAS-NMR methodology for studying the microscopic mechanism of phase transitions.     

Enantioseparation of (RS)-Bupropion and determination of configuration

Racemate of (RS)-Bupropion (Bup) has been separated by derivatization approach and thin layer chromatography (TLC). It was extracted from commercially available tablets, purified, and characterized. A new chiral derivatization reagent (CDR) was synthesized by introducing L-leucine amide and butoxy group in cyanuric chloride (CC) moiety. Derivatization reaction was carried out using a two-fold molar excess of CDR under microwave irradiation (MWI). The diastereomeric pair was separated by TLC and the same were recovered by the preparative method; these were purified and characterized. Absolute configuration of the Bup moiety in the diastereomeric derivatives was confirmed by recording their ¹HNMR spectra and thus elution order was also established.     

Secretion of human interleukin-2 fused with green fluorescent protein in recombinatn <Emphasis Type="Italic">pichia pastoris</Emphasis>

Methylotrophic yeast Pichia pastoris is convenient for the expression of eukaryotic foreign proteins owing to its potential for posttranslational modifications, protein folding, and facile culturing. In this work, human interleukin (hIL)-2 was successfully produced as a secreted fusion form in recombinant P. pastoris. By employing green fluorescent protein (GFP) as a monitoring fusion partner, clear identification of fusion protein expression and quantification of intracellular hIL-2 were possible even though there was no correlation between culture supernatant fluorescence and secreted hIL-2 owing to high media interference. Importantly, by the addition of casamino acids in basal medium, we were able to enhance threefold amount of secreted hIL-2, which was present both as a fusion and as a clipped fragment.     

Evaluation of Hydride-Based Stationary Phases for LC-MS

Two hydride-based stationary phases (cholesterol and bidentate C18) are evaluated for use in chromatographic analyses with mass spectroscopic detection. The stability of the bonded moieties and the background signal in the effluent from these columns are investigated. Separations of steroids and catecholamines are used to characterize these separation materials. Peak symmetries and efficiencies can provide additional insights into the effectiveness of the two phases. In one case a small column configuration directly connected to the mass spectrometer inlet is also tested.     

Synthesis of Biologically Active Carvacrol Compounds using Different Solvents and Supports

Natural monoterpenoids have been documented for their acute toxicity and repellent, antifeedent, reproduction inhibitory, and insecticidal actions. The present work aims to derive a variety of ether and ester compounds using polymer‐supported reactions from the polymer‐supported carvacrol anion was reacted with alkyl halides and acid chlorides to afford carvacryl ethers and esters, respectively. Furthermore, a special study on the effect of different solvents and supports revealed that Amberlite IRA 400 (chloride form) was found to be the best polymer support and acetone among the solvents.     

Effect of plant extracts on book deteriorated fungal species

Abstract

The aim of the study was to evaluate the effect of leaf extracts of four plants against some isolated fungal species from deteriorated books. Aqueous, methanol and chloroform extracts of selected plant species were screened in vitro for their antifungal activity against some book deteriorating fungal species. Fifteen species belonging to 09 genera were isolated and identified from infested books in library. Aqueous and solvent extracts of leaves of Azadiracta indica, Callistemon citrinus, Eucalyptus lanceolatus and Pongamia pinnata were tested against some dominant fungal species viz. Chaetomium spiralis, Alternaria alternata, Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus and Rhizopus stolonifer. Solvent extracts exhibited potent inhibitory activity than aqueous extracts. However, these plant extracts exhibited moderate activity against A. flavus, C. spiralis, R. stolonifer and A. alternata.