ZnO porous structures synthesized by CTAB-assisted hydrothermal process

ZnO porous structures have been fabricated by cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal process. X-ray diffraction (XRD) pattern indicated that the synthesized ZnO porous structures were hexagonal. It is found that CTAB influences the morphology of ZnO structures. On the basis of structural information provided by XRD, SEM, and TEM, a growth mechanism is proposed for the formation of ZnO porous structures.     

Electron transfer studies on cholesterol LB films assembled on thiophenol and 2-naphthalenethiol self-assembled monolayers

We have formed the cholesterol monolayer and multilayer LB films on the self-assembled monolayers of 2-naphthalenethiol (2-NT) and thiophenol (TP) and studied the electrochemical barrier properties of these composite films using cyclic voltammetry and electrochemical impedance spectroscopy. We have also characterized the cholesterol monolayer film using grazing angle FTIR, scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Cholesterol has a long hydrophobic steroid chain, which makes it a suitable candidate to assemble on the hydrophobic surfaces. We find that the highly hydrophobic surface formed by the self-assembled monolayers (SAM) of 2-NT and TP act as effective platforms for the fabrication of cholesterol monolayer and multilayer films. The STM studies show that the cholesterol monolayer films on 2-NT form striped patterns with a separation of 1.0 nm between them. The area per cholesterol molecule is observed to be 0.64 nm2 with a tilt angle of about 28.96 degrees from the surface normal. The electrochemical studies show a large increase in charge transfer resistance and lowering of interfacial capacitance due to the formation of the LB film of cholesterol. We have compared the behavior of this system with that of cholesterol monolayer and multilayers formed on the self-assembled monolayer of thiophenol.     

Imine-functionalized, fluorescent organomercury and -tellurium compounds

Unsymmetrical diorganotellurium(IV) dihalides, Ar′(Ar)TeCl₂ [Ar′ = 2-(R-CHN-C₆H₃Me; R = 1-pyrenyl, 9-anthracenyl and 9-phenanthrenyl; Ar = 4-MeO-C₆H₄, 1-C₁₀H₇, 2,4,6-Me₃-C₆H₂, C₆H₅, 4-Me-C₆H₄] were synthesized from transmetallation reactions of Ar′HgCl and ArTeCl₃. Orthomercuration of the Schiff’s bases (Ar′H) afforded Ar′HgCl. All of these compounds have been characterized with the help of IR, multinuclear (¹H, ¹³C) solution NMR and ESI-HRMS spectrometry. X-ray crystal structures of pyrenyl Ar′HgCl; pyrenyl Ar′(Ar)TeCl₂ (Ar = 4-MeO-C₆H₄); anthranyl Ar′(Ar)TeCl₂ (Ar = 4-MeO-C₆H₄ and 1-C₁₀H₇) and; phenathranyl Ar′(Ar)TeCl₂ (Ar = 1-C₁₀H₇) have been determined. Intramolecular Hg/Te?N interactions are present in these structures. Fluorescence studies of these compounds have also been carried out.     

Linear versus bent bonding in metal-phosphinidene complexes: Theoretical studies of the electrophilic phosphinidene complexes [(Cp)(CO)2MPMe)], [(Cp)(CO)3MPMe)] (M = Cr, Mo, W)

Density functional theory calculations have been performed for the title phosphinidene complexes using the exchange correlation functionals BP86 and B3LYP. The optimized bond lengths and angles of the model compounds are in excellent agreement with experiment. The M-P bond lengths in linear phosphinidene complexes correspond to a Pauling bond order of ∼ 3. The bent geometries at phosphorus in the bent metal phosphinidene complexes are consistent with the presence of a trivalent phosphorus(III) center which is singly bonded to carbon and doubly bonded to transition metal. The analysis of the delocalized Kohn-Sham orbitals shows the polarization of the M-P σ bonding orbitals towards the phosphorus atom in the MPMe bonds, while in the MPMe bond, the contributions of metal and phosphorus are almost the same. In the linear phosphinidene complexes the contributions of the covalent bonding ΔE_orb are more than the electrostatic interaction ΔE_elstat. The bent phosphinidene complexes have a lower degree of covalent bonding than the linear phosphinidene complexes. The major differences between the linear and bent phosphinidene complexes are found in the degree of π-bonding. The MPMe bonds show a true M-P π bond and a deviated π bond due to slight bent M-P-C bond angles. The MPMe bonds show a true M-P π bond and a lone-pair on phosphorus.     

Inulinase synthesis from a mesophilic culture in submerged cultivation

A newly isolated mesophilic bacterial strain from dahlia rhizosphere, identified as Staphylococcus sp. and designated as RRL-M-5, was evaluated for inulinase synthesis in submerged cultivation using different carbon sources individually or in combination with inulin as substrate. Inulin appeared as the most favorable substrate at a 0.5–1.0% concentration. Media pH influenced the enzyme synthesis by the bacterial strain, which showed an optimum pH at 7.0–7.5. Supplementation of fermentation medium with external nitrogen (organic and inorganic) showed a mixed impact on bacterial activity of enzyme synthesis. The addition of soybean meal and corn steep solid resulted in about an 11% increase in enzyme titers. Among inorganic nitrogen sources, ammonium sulfate was found to be the most suitable. Maximum enzyme activities (446 U/L) were obtained when fermentation was carried out at 30°C for 24 h with a medium containing 0.5% inulin as a sole carbon source and 0.5% soybean meal as the nitrogen source. Bacterial inulinase could be a good source for the hydrolysis of inulin for the production of d-fructose.     

Toward resistance‐compromised DHFR inhibitors part 1: Combined structure/ligand‐based virtual screenings and ADME‐Tox profiling

The front‐line antimalarial drugs, for example, chloroquine, mefloquine, sulfadoxine, pyrimethamine, atovaquone, and artemether, are often failing because of the worldwide spread of drug‐resistant parasites. There has been significant recent interest in virtual screening to drive innovative drug discovery and to combat resistance efforts for a wide range of diseases. In fact, virtual screening has become the “gold standard” for major pharmaceutical industries and some university groups. Therefore, we present herein a structure‐based LibDock/CHARMM modeling and a set of appropriate scoring function evaluation criteria: correlation, consensus score, correlation‐based score, generally applicable replacement for root‐mean‐square deviation using a training set of 38 phenylthiazolyl‐1,3,5‐triazines from our previous reports and followed by a ligand‐based model to identify molecular features like hydrogen‐bond acceptor, hydrogen‐bond donor, hydrophobicity, and ring aromatic (RA) using Catalyst HipHop/HypoGen module. Next, TOPKAT module was applied to predict ADME‐Tox properties. The combined structure/ligand‐based approaches inadvertently arrived at a conserved Arg122 binding site from reliable LigScore1_dreiding top scoring function and are subsequently attributed to reserve important interactions and combat mutational drug resistance. The best pharmacophore model suggested that 1 hydrogen‐bond acceptor, 2 hydrophobicities, and 1 ring aromatic feature with good sensitivity at 0.50, specificity at 0.66, enrichment at 1.60, and accuracy at 0.50. Finally, good pharmacokinetics, metabolic stability, and toxicity endpoints were predicted in the comparison of proguanil and cycloguanil. These druggability insights are useful for researchers to deliver more effective, safer, both wild‐type and resistance‐compromised, and more economical dihydrofolate reductase inhibitors in the near future.     

Studies on differential sensing of dopamine at the surface of chemically sensitized ormosil-modified electrodes

We report herein the preparation of few chemically sensitized organically modified sol–gel glass (ormosil) films and sensing of dopamine at the surface of the modified electrodes derived from these films. The chemical sensitization in ormosil-modified electrodes is introduced by incorporating: (a) potassium ferricyanide and (b) either Nafion, or dibenzo-18-crown-6 or in situ generated Prussian blue from potassium ferricyanide. Electrochemical sensing of dopamine on the surfaces of these modified electrodes have been investigated and found that: (i) the presence of dibenzo-18-crown-6 facilitate the magnitude of dopamine sensing, (ii) conversion of potassium ferricyanide into Prussian blue also enhances the magnitude of dopamine sensing as compared to that of control and Nafion sensitized modified electrodes, (iii) both dibenzo-18-crown-6 and Nafion sensitized ormosil-modified electrodes are found selective to dopamine in the presence of ascorbic acid present under physiological concentration range. These finding again directed our attention to investigate the sensing of dopamine: (a) on dibenzo-18-crown-6 incorporated within Prussian blue sensitized modified electrode and (b) in the presence of varying concentrations of dibenzo-18-crown-6 in the Prussian blue modified electrodes. The investigations made on these lines again suggested the following: (1) increase in dibenzo-18-crown-6 concentrations in the modified electrode increases the magnitude of dopamine sensing upto an optimum concentration of macrocycle; (2) the detection limit of dopamine sensing goes down to 30 nM as compared to that of dibenzo-18-crown-6 incorporated with potassium ferricyanide which was found to the order of 100 nM. Investigations of the interference of ascorbic acid revealed that the presence of dibenzo-18-crown-6 introduces selectivity in dopamine sensing in the presence such common interfering analyte like ascorbic acid.     

Simultaneous quantitation of acetylsalicylic acid and clopidogrel along with their metabolites in human plasma using liquid chromatography tandem mass spectrometry

The interest in therapeutic drug monitoring has increased over the last few years. Inter‐ and intra‐patient variability in pharmacokinetics, plasma concentration related toxicity and success of therapy have stressed the need of frequent therapeutic drug monitoring of the drugs. A sensitive, selective and rapid liquid chromatography coupled with tandem mass spectrometry (LC‐MS/MS) method was developed for the simultaneous quantification of acetylsalicylic acid (aspirin), salicylic acid, clopidogrel and carboxylic acid metabolite of clopidogrel in human plasma. The chromatographic separations were achieved on Waters Symmetry Shield^TM C₁₈ column (150 × 4.6 mm, 5 µm) using 3.5 mm ammonium acetate (pH 3.5)–acetonitrile (10:90, v/v) as mobile phase at a flow rate of 0.75 mL/min. The present method was successfully applied for therapeutic drug monitoring of aspirin and clopidogrel in 67 patients with coronary artery disease. Copyright © 2015 John Wiley & Sons, Ltd.     

Fine‐Tuning of Saponification‐Triggered Gelation by Strategic Modification of Peripheral Substituents: Gelation Regulators

A pioneering approach towards controlling the efficiency of saponification assisted gelation in ethyl ester based Zn^II‐complexes have been described. Using four new ester containing bis‐salen Zn^II complexes ( C1–C4 ) involving different para‐azo phenyl substituted ligands it has been clearly shown that gelation efficiency is greatly influenced by the electronic effects of the substituents (‐H ( C1 ), ‐CH₃ ( C2 ), ‐NO₂ ( C3 ), and ‐OCH₃ ( C4 )). Morphological, photophysical, and rheological investigations corroborated the experimental observations well and established that gelation efficiency was enhanced with electron‐withdrawing characteristics of substituents ( C4 < C2 < C1 < C3 ). This conclusion was also supported by DFT studies.     

Effective Floquet Hamiltonian for spin I = 1 in magic angle spinning NMR using contact transformation

Contact transformation is an operator transformation method in time-independent perturbation theory which is used successfully in molecular spectroscopy to obtain an effective Hamiltonian. Floquet theory is used to transform the periodic time-dependent Hamiltonian, to a time-independent Floquet Hamiltonian. In this article contact transformation method has been used to get the analytical representation of Floquet Hamiltonian for quadrupolar nuclei with spin I = 1 in the presence of an RF field and first order quadrupolar interaction in magic angle spinning NMR experiments. The eigenvalues of contact transformed Hamiltonian as well as Floquet Hamiltonian have been calculated and a comparison is made between the eigenvalues obtained using the two Hamiltonians.