Metal‐Helix Frameworks from Short Hybrid Peptide Foldamers

The potential of structured peptides has not been explored much in the design of metal‐organic frameworks (MOFs). This is partly due to the difficulties in obtaining stable secondary structures from the short α‐peptide sequences. Here we report the design, crystal conformations, coordination site dependent different silver coordinated frameworks of short α,γ‐hybrid peptide 12‐helices consisting of terminal pyridyl moieties and the utility of metal‐helix frameworks in the adsorption of CO₂. Upon silver ion coordination the 12‐helix terminated by the 3‐pyridyl derivatives adopted a 2:2 macrocyclic structure, while the 12‐helix terminated by the 4‐pyridyl derivatives displayed remarkable porous metal‐helix frameworks. Both head‐to‐tail intermolecular H‐bonds of the 12‐helix and metal ion coordination have played an important role in stabilizing the ordered metal‐helix frameworks. The studies described here open the door to design a new class of metal‐organic‐frameworks from peptide foldamers.     

Metalo Hydrogen-Bonded Organic Frameworks (MHOFs) as New Class of Crystalline Materials for Protonic Conduction

Recently, proton conduction has been a thread of high potential owing to its wide applications in fuel-cell technology. In the search for a new class of crystalline materials for protonic conductors, three metalo hydrogen-bonded organic frameworks (MHOFs) based on [Ni(Imdz)₆]²⁺ and arene disulfonates (MHOF1 and MHOF2) or dicarboxylate (MHOF3) have been reported (Imdz=imidazole). The presence of an ionic backbone with charge-assisted H-bonds, coupled with amphiprotic imidazoles made these MHOFs protonic conductors, exhibiting conduction values of 0.75×10⁻³, 3.5×10⁻⁴ and 0.97×10⁻³ S cm⁻¹, respectively, at 80 °C and 98 % relative humidity, which are comparable to other crystalline metal-organic framework, coordination polymer, polyoxometalate, covalent organic framework, and hydrogen-bonded organic framework materials. This report initiates the usage of MHOF materials as a new class of solid-state proton conductors.     

Synthesis and characterization of nanostructured (Pb1− x Sr x )TiO3 thin films by a modified chemical route

The coating solutions of nanostructured (Pb_{1– x} Sr _x )TiO₃ (PST) thin films have been prepared by the sol–gel combined metallo-organic decomposition method. The coating solutions were deposited on Pt/Ti/SiO₂/Si substrates using a spin-coating technique with spinning speed of 4300 rpm and annealed at 650°C. The effect of Sr content in reducing the grain size and tetragonal distortion of PST films has been studied. The optimum conditions for crystalline phase formation in the films have been analyzed by thermogravimetric, differential thermal analysis and Fourier transform infrared spectroscopy. The phase and microstructure of the films were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). The XRD pattern shows that the PST thin films are crystallized into tetragonal structures without any impurity phase and the distortion ratio reduces with increasing Sr concentration. The AFM results indicate an increase in grain size with increasing annealing temperature of the film and reduction in grain size with increasing Sr concentration.     

Effect of non-zero Schottky barrier on the J-V characteristics of organic diodes

Current-voltage (J -Vcharacteristics of poly(3-hexylthiophene) (P3HT) are studied at different temperatures upto high voltages ∼ 20 V in the hole-only device configuration. The characteristics are studied in the temperature range 310-210K. In the intermediate voltage range the J -V characteristics follow J V ^l+1 , where l > 1 . As the voltage increases to high values J still varies as a power law i.e. as V^m, but contrary to the literature result m becomes < 2 . This behavior is explained theoretically in terms of non-zero injection Schottky barriers. The complete analytical expressions for the actual trap filled limit voltage (V′ _TFL) and J -V curves beyond V′ _TFL are presented.     

Microorganisms: A Potential Source of Bioactive Molecules for Antioxidant Applications

Oxidative stress originates from an elevated intracellular level of free oxygen radicals that cause lipid peroxidation, protein denaturation, DNA hydroxylation, and apoptosis, ultimately impairing cell viability. Antioxidants scavenge free radicals and reduce oxidative stress, which further helps to prevent cellular damage. Medicinal plants, fruits, and spices are the primary sources of antioxidants from time immemorial. In contrast to plants, microorganisms can be used as a source of antioxidants with the advantage of fast growth under controlled conditions. Further, microbe-based antioxidants are nontoxic, noncarcinogenic, and biodegradable as compared to synthetic antioxidants. The present review aims to summarize the current state of the research on the antioxidant activity of microorganisms including actinomycetes, bacteria, fungi, protozoa, microalgae, and yeast, which produce a variety of antioxidant compounds, i.e., carotenoids, polyphenols, vitamins, and sterol, etc. Special emphasis is given to the mechanisms and signaling pathways followed by antioxidants to scavenge Reactive Oxygen Species (ROS), especially for those antioxidant compounds that have been scarcely investigated so far.     

SYNTHESIS, CHARACTERIZATION AND CATALYTIC ACTIVITY OF N,N''''-BIS(3-ALLYL SALICYLIDENE)ETHYLENEDIAMINE COBALT(Ⅱ) SCHIFF BASE COMPLEX ANCHORED ON A NEW POLYMER SUPPORT

INTRODUCTIONAlthough homogeneous catalysts have higher selectivity and act under mild experimental conditions in variousreactions they have problems of separation and recovery from reaction products. Hence current research activitiesare aimed at developing catalysts of coordination compounds anchored on suitable supports[1,2]. This techniqueof immobilization of catalyst on an inert support increases the catalytic activity, selectivity, efficiency[3],operational flexibility and stability. …     

Spider Monkey Optimization algorithm for numerical optimization

Swarm intelligence is one of the most promising area for the researchers in the field of numerical optimization. Researchers have developed many algorithms by simulating the swarming behavior of various creatures like ants, honey bees, fish, birds and the findings are very motivating. In this paper, a new approach for numerical optimization is proposed by modeling the foraging behavior of spider monkeys. Spider monkeys have been categorized as fission–fusion social structure based animals. The animals which follow fission–fusion social systems, split themselves from large to smaller groups and vice-versa based on the scarcity or availability of food. The proposed swarm intelligence approach is named as Spider Monkey Optimization (SMO) algorithm and can broadly be classified as an algorithm inspired by intelligent foraging behavior of fission–fusion social structure based animals.     

Enantioselective nitroaldol (Henry) reaction using copper(II) complexes of (-)-sparteine

The dichloro[(-)-sparteine-N,N']copper(II) complex provides Henry adducts with high enantioselectivities (73-97% ee) in Henry reaction between nitromethane and various aldehydes.