Transitions of bipolar to radial orientation of liquid crystal droplets in amphiphilic system of PDLC film

The orientation order of nanoscale droplets of thermotropic liquid crystals (LCs) suspended in polymer dispersed liquid crystal (PDLC) solutions prepared with different medias (e.g., polymers, surfactants, nonpolar materials like dyes) respond sensitively and differently via molecular interactions. Such a valuable knowledge provides basis for understanding the properties of PDLC devices. Previously, many studies have explored the droplets size, electro-optical property variations in PDLC films by varying the materials types and its compositions. However, the variations in droplet orientation order with respect to material type and composition provide a new class of study in this particular field. The current study explored the transition in droplet orientation from bipolar to radial on varying the amphiphilic block copolymer concentrations. Further, the variations in surface energies of LCs in different series of block copolymer medias were investigated by contact angle measurements.     

Synthesis and Structure of the Cyclic Borenium Cation 1,1,3,3-tetramethyl-1,3λ<Superscript>4</Superscript>,2-diazaborolidin-1-ium chloride

The solid state structure of an N-heterocyclic borane 1,1,3,3-tetramethyl-1,3λ⁴,2-diazaborolidin-1-ium chloride is reported. This molecule features numerous Cl?H hydrogen bonds.

Graphical Abstract

The crystal structure of 1,1,3,3-tetramethyl-1,3λ⁴,2-diazaborolidin-1-ium chloride shows multiple C–H?Cl interactions in the solid state.

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Phenolic Constituents from Wendlandia tinctoria var. grandis (Roxb.) DC. Stem Deciphering Pharmacological Potentials against Oxidation,Hyperglycemia, and Diarrhea: Phyto-Pharmacological and Computational Approaches

Wendlandia tinctoria var. grandis (Roxb.) DC. (Family: Rubiaceae) is a semi-evergreen shrub distributed over tropical and subtropical Asia. The present research intended to explore the pharmacological potential of the stem extract of W. tinctoria, focusing on the antioxidant, hypoglycemic, and antidiarrheal properties, and to isolate various secondary metabolites as mediators of such activities. A total of eight phenolic compounds were isolated from the dichloromethane soluble fraction of the stem extract of this plant, which were characterized by electrospray ionization (ESI) mass spectrometric and ¹H NMR spectroscopic data as liquiritigenin (1), naringenin (2), apigenin (3), kaempferol (4), glabridin (5), ferulic acid (6), 4-hydroxybenzoic acid (7), and 4-hydroxybenzaldehyde (8). The dichloromethane soluble fraction exhibited the highest phenolic content (289.87 ± 0.47 mg of GAE/g of dried extract) and the highest scavenging activity (IC₅₀ = 18.83 ± 0.07 µg/mL) against the DPPH free radical. All of the isolated compounds, except 4-hydroxybenzaldehyde, exerted a higher antioxidant effect (IC₅₀ = 6.20 ± 0.10 to 16.11 ± 0.02 μg/mL) than the standard butylated hydroxytoluene (BHT) (IC₅₀ = 17.09 ± 0.01 μg/mL). Significant hypoglycemic and antidiarrheal activities of the methanolic crude extract at both doses (200 mg/kg bw and 400 mg/kg bw) were observed in a time-dependent manner. Furthermore, the computational modeling study supported the current in vitro and in vivo findings, and the isolated constituents had a higher or comparable binding affinity for glutathione reductase and urase oxidase enzymes, glucose transporter 3 (GLUT 3), and kappa-opioid receptor, inferring potential antioxidant, hypoglycemic, and antidiarrheal properties, respectively. This is the first report of all of these phenolic compounds being isolated from this plant species and even the first demonstration of the plant stem extract’s antioxidant, hypoglycemic, and antidiarrheal potentials. According to the current findings, the W. tinctoria stem could be a potential natural remedy for treating oxidative stress, hyperglycemia, and diarrhea. Nevertheless, further extensive investigation is crucial for thorough phytochemical screening and determining the precise mechanisms of action of the plant-derived bioactive metabolites against broad-spectrum molecular targets.     

Biotransformation of (+)-androst-4-ene-3,17-dione

Fermentation of (+)-androst-4-ene-3,17-dione (1) with Curvularia lunata for 10 days yielded five oxidative and reductive metabolites, androsta-1,4-diene-3,17-dione (2), 17beta-hydroxyandrosta-1,4-dien-3-one (3), 11alpha-hydroxyandrost-4-ene-3,17-dione (4), 11alpha,17beta-dihydroxyandrost-4-en-3-one (5) and 15alpha-hydroxyandrosta-1,4-dien-17-one (6). The structures of these metabolites were elucidated on the basis of spectroscopic techniques. These microbially transformed products were assayed against the clinically important enzymes, tyrosinase and prolyl endopeptidase.     

New cholinesterase inhibiting steroidal alkaloids from the leaves of Sarcococca coriacea of Nepalese origin

From the leaves of Sarcococca coriacea two new steroidal alkaloids, epoxynepapakistamine-A [(20S)-20-(N-methylamino)-3beta-(tigloylamino)-5alpha-pregna-16alpha,17alpha-epoxy-2beta,4beta-di-O-acetate] (1), and epoxysarcovagenine-D [(20S)-20-(N-methylamino)-3beta-(tigloylamino)-5alpha-pregna-2-en-16alpha,17alpha-epoxy-4-one] (2), and two known compounds funtumafrine C [(20S)-20-(N,N-dimethylamino)-5alpha-pregna-3-one] (3) and N-methylfuntumine (4) were isolated. Their structures were elucidated on the basis of their spectral properties. The compounds 1, 3 and 4 were found to have cholinesterase inhibitory activity when tested for the inhibition of electric eel acetylcholinesterase and horse serum butyrylcholinesterase. They inhibited both enzymes in a concentration dependent fashion.     

Synthesis of novel Schiff base doped sol–gel silicas

Sulfonamide Schiff bases were doped uniformly in silica sol–gels prepared from liquid precursors by a fast and easy way at room temperature and processed to form xerogels. Schiff bases are efficient chelating agents, bioactive and catalytically active compounds. The structures of the newly synthesized Schiff base doped xerogels were elucidated by their physical (morphology, surface area, porosity), spectral (FTIR) and analytical (CHNSO/Si) data. The powder X-ray diffraction studies were carried out to confirm the formation of single phase. Characterization confirmed that Schiff base molecules are entrapped inside the pores as well as physically bound onto the silica surface. All Schiff base doped xerogels are stable mesoporous materials showing hydrophilic properties. Loadings of Schiff bases from 0.10 to 0.23 g/g of xerogel were obtained resulting amorphous materials. The doping of Schiff bases with xerogel caused change in surface area, pore volume and pore diameter of xerogel without damaging the main framework of siliceous skeleton. Morphology and colour of xerogel was also changed after doping. The entrapment of Schiff bases in xerogel caused increase in their decomposition temperatures. The final Schiff base doped xerogels show remarkable thermal stability.     

Insulator-metal transitions induced by electric field and photoirradiation in organic Mott insulator deuterated κ-(BEDT-TTF)2Cu[N(CN)2]Br

The Mott insulator-metal transition induced by an external stimulus such as electric field, pressure, chemical doping, or photoirradiation has received considerable attention because of the potential use in new optoelectronic functional devices. Here we report an abrupt Mott insulator-metal transition observed as a current jump in a molecular-based Mott insulator, namely, deuterated κ-(BEDT-TTF)(2)Cu[N(CN)(2)]Br, where BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene, upon application of a pulsed voltage of certain magnitude (threshold voltage). Furthermore, the threshold voltage needed for the transition is shown to be reduced by photoirradiation. Thus, the Mott insulator-metal transition can be controlled by a combination of an external electric field and photoirradiation.     

Synthesis, characterization, anti-inflammatory and in vitro antimicrobial activity of some novel alkyl/aryl substituted tertiary alcohols

The synthesis of some novel alkyl/aryl substituted tertiary alcohols was accomplished in two steps. The synthetic route involves preparation of Grignard reagents by treating alkyl/aryl bromides with magnesium turnings in dry ether. Then substituted chalcones were reacted with the Grignard reagents to afford alkyl/aryl substituted tertiary alcohols 1-10. The structures of the synthesized compounds were assigned on the basis of FT-IR, 1H-NMR, 13C-NMR and mass spectroscopic data. The in vivo anti-inflammatory activity of the synthesized compounds was evaluated using the carrageenan-induced hind paw edema method and was compared with that of ibuprofen. Some of the newly synthesized compounds showed promising anti-inflammatory activity. The tertiary alcohols 1-10 were also screened for antibacterial activity against ten bacterial strains using seven Gram-positive and three Gram-negative bacteria and for antifungal activity against Aspergillus Flavus, Aspergillus Niger and Aspergillus pterus. Tertiary alcohols 1-10 were found to exhibit good to excellent antimicrobial activities compared to levofloxacin and fluconazole used as standard drugs.     

Photorefractive performance of a CdSe/ZnS core/shell nanoparticle-sensitized polymer

We report the photorefractive performance of a polymer composite sensitized by CdSe/ZnS core/shell nanoparticles, and also comprising poly(N-vinylcarbazole) and an electro-optic chromophore. The nanoparticles are characterized by absorption and photoluminescence spectroscopy, elemental analysis, transmission electron microscopy, and powder x-ray diffraction. The electro-optic response of the composite is measured independently of the photorefractive effect by transmission ellipsometry. An asymmetric two-beam coupling gain of 30.6+/-0.4 cm(-1) is obtained, confirming photorefractivity. Degenerate four-wave mixing is used to assess photorefractive performance and, at a poling field of 70 V microm(-1), yields a diffraction efficiency of 4.21%+/-0.03%, a holographic contrast of 3.05 x 10(-4)+/-1 x 10(-6), a space-charge rise time of 25+/-2 s, and a sensitivity of 4.7 x 10(-5)+/-4 x 10(-6) cm3 J(-1). These results constitute a significant improvement on the performance of previous nanoparticle-sensitized photorefractive polymer composites.     

Investigating the Calculation of Rotational Viscosity of the Mixture Comprising Different Kinds of Liquid Crystals:Molecular Dynamics Computer Simulation Approach

Molecular dynamics (MD) computer simulation techniques, as a powerful tool commonly utilized by the liquid crystal display (LCD) community, usually are employed for computing the equilibrium and transport properties of a classical many body system, since they are very similar to real experiments in many respects. In this paper we present molecular dynamics computer simulation results taken for a mixture of the two different kinds of nematic liquid crystals (LCs). We calculated rotational viscosity from Brownian behavior with friction of the mean director of the mixture comprising pentylcyanobiphenol (5CB) and decylcyanobiphenol (10CB) by using molecular dynamics computer simulation, where intermolecular potential parameter is Generalized AMBER force field (GAFF). Our computed results show a good agreement with the experimental results.