Synthesis,characterization, and photovoltaic properties of dithienylbenzobisazole‐dithienylsilole copolymers

Three conjugated polymers comprised of dioctyl‐dithieno‐[2,3‐b:2',3'‐d]silole and a donor‐acceptor‐donor triad of either cis‐benzbisoxazole, trans‐benzobisoxazole or trans‐benzobisthiazole were synthesized via the Stille cross‐coupling reaction. The impact of varying the heteroatoms and/or the location within the benzobisazole moiety on the optical and electronic properties of the resulting polymers was evaluated via cyclic voltammetry and UV‐Visible spectroscopy. All of the polymers have similar optical band‐gaps of ～1.9 eV and highest occupied molecular orbital levels of ? 5.2 eV. However, the lowest unoccupied molecular orbitals (LUMO) ranged from ? 3.0 to ? 3.2 eV. Interestingly, when the polymers were used as donor materials in bulk‐heterojunction photovoltaic cells with PC₇₁BM as the electron‐acceptor, the benzobisoxazole‐based polymers gave slightly better results than the benzobisthiazole‐containing polymers with power conversion efficiencies up to 3.5%. These results indicate that benzobisoxazoles are promising materials for use in OPVs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1533–1540     

[32]π Fused Core‐Modified Heptaphyrin with Möbius Aromaticity

A new fused core‐modified 32π heptaphyrin with Möbius aromatic character is reported. The ¹H NMR data indicated a weak Möbius aromaticity at 298 K; however, at 213–183 K, the molecule predominates [4n]π Möbius conformation with strong diatropic ring current, which was further confirmed by X‐ray analysis. The protonation experiment led to preservation of the Möbius aromaticity at 298 K. Nevertheless, the experimental results were further supported by theoretical studies. Overall, this study represents the first example of Möbius aromatic fused core‐modified expanded porphyrin.     

HPTLC—Densitometry Method for Simultaneous Determination of Major Lignans and Flavonoids in Podophyllum hexandrum

JPC – Journal of Planar Chromatography – Modern TLC - A new quantitative method using thin-layer chromatography silica gel 60F254 plates as the stationary phase and the mobile phase...     

Beyond Chemoselectivity: Catalytic Site‐Selective Aldolization of Diketones and Exploitation for Enantioselective Alzheimer's Drug Candidate Synthesis

Site selectivity, differentiating instances of the same functional group type on one substrate, represents a forward‐looking theme within chemistry: reduced dependence on protection/deprotection protocols for increased overall yield and step‐efficiency. Despite these potential benefits and the expanded tactical advantages afforded to synthetic design, site selectivity remains elusive and especially so for ketone‐based substrates. Herein, site‐selective intermolecular mono‐aldolization has been demonstrated for an array of prochiral 4‐keto‐substituted cyclohexanones with concomitant regio‐, diastereo‐, and enantiocontrol. Importantly, the aldol products allow rapid access to molecularly complex ketolactones or keto‐1,3‐diols, respectively containing three and four stereogenic centers. The reaction conditions are of immediate practical value and general enough to be applicable to other reaction types. These findings are applied in the first enantioselective, formal, synthesis of a leading Alzheimer's research drug, a γ‐secretase modulator (GSM), in the highest known yield.     

Growth of small diameter multi-walled carbon nanotubes by arc discharge process

Multi-walled carbon nanotubes （MWCNTs） are grown by arc discharge method in a controlled methane environment. The arc discharge is produced between two graphite electrodes at the ambient pressures of 100 tort, 300 torr, and 500 torr. Arc plasma parameters such as temperature and density are estimated to investigate the influences of the ambient pressure and the contributions of the ambient pressure to the growth and the structure of the nanotubes. The plasma temperature and density are observed to increase with the increase in the methane ambient pressure. The samples of MWCNT synthesized at different ambient pressures are analyzed using transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. An increase in the growth of MWCNT and a decrease in the inner tube diameter are observed with the increase in the methane ambient pressure.     

Metabolic Engineering of Biosynthetic Pathway for Production of Renewable Biofuels

Metabolic engineering is an important area of research that involves editing genetic networks to overproduce a certain substance by the cells. Using a combination of genetic, metabolic, and modeling methods, useful substances have been synthesized in the past at industrial scale and in a cost-effective manner. Currently, metabolic engineering is being used to produce sufficient, economical, and eco-friendly biofuels. In the recent past, a number of efforts have been made towards engineering biosynthetic pathways for large scale and efficient production of biofuels from biomass. Given the adoption of metabolic engineering approaches by the biofuel industry, this paper reviews various approaches towards the production and enhancement of renewable biofuels such as ethanol, butanol, isopropanol, hydrogen, and biodiesel. We have also identified specific areas where more work needs to be done in the future.     

Transportation of drug–gold nanocomposites by actinomyosin motor system

Nanotechnology is playing an important role in drug delivery to overcome limitations of conventional drug delivery systems in terms of solubility, in vivo stability, pharmacokinetics, and bio-distribution. The controlled transportation of drug into the cell and within the cell is a major challenge to be addressed. Cellular molecular motors have been exploited for their cargo carrying capacity for various applications including engineering and health care. Combination of nanotechnology and biomolecular motors can address some of the challenges in drug delivery. In the present study, transportation of drug nanocomposites has been demonstrated. Nanocomposites of 6-mercaptopurine and levodopa drugs (cancer and Parkinson’s disease, respectively) were prepared with gold nanoparticles (GNPs) by covalent attachment and these nanocomposites were attached to actin filaments. These nanocomposites were in-turn transported by actin filaments on myosin tracks. Characterization of drug nanocomposites formation was done by UV–Vis spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and confocal microscopy. GNP composites of 6-mercaptopurine and levodopa were formed by sulfide and amide bond formation, respectively. Average velocity of actin filament attached to nanocomposites was found to be 3.17 and 3.89 μm/s for levodopa and 6-mercaptopurine, respectively, as compared to actin filaments with velocity of 4.0–6.0 μm/s. Three concepts have been proposed for the study of drug transportation into the cell based on polycationic complex formation, interaction of actin with cellular myosin and Biomolecular Adaptor for Retrograde Transport (BART) technology. The aspects of this study heads toward the development of an approach to utilize molecular motors for nanoscale transportation endogenously.     

Development of thermoplastic polyurethane/polyaniline-doped membranes for the separation of glycine through electrodialysis

Recently, membrane-based separation processes, particularly electrodialysis, have attracted attention for the separation and purification of organic and amino acids from animal feedstock waste. In this study, cation exchange membranes were synthesized by making a composite of thermoplastic polyurethane and polyaniline (PANI) via the doping of various aromatic sulfonic acids, such as β -naphthol sulfonic acid and phenol sulfonic acid. The PANI was prepared using a standard method, which was further used in the composite blending at varying concentrations of 10%–20%. The impact of the concentration of PANI and the nature of the dopant on the membrane characteristics were comparatively studied. The membranes were analyzed by electric conductivity, water swelling, morphological studies (SEM), and thermogravimetric analysis. The membranes were used for the separation of glycine hydrochloride via electrodialysis.     

Green chemistry-assisted synthesis of biocompatible Ag,Cu, and Fe2O3 nanoparticles

Green chemistry-assisted biocompatible copper (Cu), silver (Ag), and iron oxide (Fe₂O₃) nanoparticles (NPs) synthesis along with surface modification using Koelreuteria apiculata is demonstrated in this research, for the first time. Appropriate analytical techniques were utilized to confirm the preparation, spherical morphology, and crystalline structure of each of the NPs. The antioxidant nature of synthesized NPs was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. Besides, the antimicrobial activity was also performed using bacterial strains of Staphylococcus aureus, Escherichia coli, and Salmonella typhi. Aspergillus sp. was designed as marker specie for the antifungal studies. The outcomes of NPs exposure, analyzed with reference to Chlorella sp. of the algal family exhibit the numerical values around 833% for AgNPs, 497% of CuNPs, and 456% for Fe₂O₃NPs. Phytotoxicity assay performed on the seeds of Vigna radiata and Cicer arietinum further validate the accordant nature of NPs towards vivacity. Allium cepa was also used as a test model to ascertain the genotoxic effects of the NPs wherein the mitotic index (MI) was calculated for AgNPs, CuNPs, and Fe₂O₃NPs as 42.1, 51.7, and 54.2% respectively. The outcomes of this research proved the suitability and affordability of our NPs developed using green synthesis for new industrial applications of in-situ reduction of carcinogenic compounds from water and soil.