Determination of polarity parameters for liquid crystals using solvatochromic method in anisotropic and isotropic phases

The use of liquid crystals (LCs) as anisotropic solvents is desired for various potential applications and usually for other organic and inorganic compounds. In this work, solvent polarity parameters are obtained using a spectroscopic method for four LCs with a range of high and low dielectric anisotropy (?ε). Solvatochromic polarity parameters for these LCs were defined via Kamlet–Abboud–Taft polarity functions characterizing different temperatures and phases, isotropic and anisotropic, and using the Reichardt’s dye and 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio) phenolate standard probe. The investigated polarity parameters reveal the effects of LC media on the photo-physical behaviour of solute molecules in isotropic and anisotropic media. Subsequently, a new LC polarity parameter (Z_o) is introduced as an overall matrix anisotropy polarity parameter to characterize variation between isotropic and anisotropic phases. The values of Z_o are sorted from higher to lower dielectric anisotropies (?ε).     

Cloning and Characterization of Cold-Adapted α-Amylase from Antarctic <Emphasis Type="Italic">Arthrobacter agilis</Emphasis>

In this study, the gene encoding an α-amylase from a psychrophilic Arthrobacter agilis PAMC 27388 strain was cloned into a pET-28a(+) vector and heterologously expressed in Escherichia coli BL21(DE3). The recombinant α-amylase with a molecular mass of about 80 kDa was purified by using Ni²⁺-NTA affinity chromatography. This recombinant α-amylase exhibited optimal activity at pH 3.0 and 30 °C and was highly stable at varying temperatures (30–60 °C) and within the pH range of 4.0–8.0. Furthermore, α-amylase activity was enhanced in the presence of FeCl₃ (1 mM) and β-mercaptoethanol (5 mM), while CoCl₂ (1 mM), ammonium persulfate (5 mM), SDS (10 %), Triton X-100 (10 %), and urea (1 %) inhibited the enzymatic activity. Importantly, the presence of Ca²⁺ ions and phenylmethylsulfonyl fluoride (PMSF) did not affect enzymatic activity. Thin layer chromatography (TLC) analysis showed that recombinant A. agilis α-amylase hydrolyzed starch, maltotetraose, and maltotriose, producing maltose as the major end product. These results make recombinant A. agilis α-amylase an attractive potential candidate for industrial applications in the textile, paper, detergent, and pharmaceutical industries.     

Effect of addition of 1-butyl-3-methylimidazolium thiocyanate on conductivity of Na-containing polymer electrolyte

Research in the environmentally friendly energy field has grown rapidly due to severe problems such as global warming and climate change. Sodium-ion technology is one of the most promising alternatives to lithium-ion batteries. Use of ionic liquids containing thiocyanate anion has been considered because of their low cost, low viscosity, and nonhazardous nature. In this work, polyethylene oxide (PEO)–sodium perchlorate (NaClO₄) samples containing different amounts of 1-butyl-3-methylimidazolium thiocyanate ionic liquid were prepared by a solution casting method. Addition of the ionic liquid to the PEO–NaClO₄ electrolyte further increased the ionic conductivity. The electrolyte containing 30 wt% ionic liquid exhibited the maximum ionic conductivity of ~5.0 × 10^?4 S/cm at room temperature. Fourier-transform infrared (FT-IR) spectroscopy revealed the interaction between the polymer chain and salt ion complexes for various sodium salt contents. Differential scanning calorimetry (DSC) demonstrated that the crystallinity was reduced by addition of 1-butyl-3-methylimidazolium thiocyanate ionic liquid.     

Effects of mechanical stretching on average orientation of cellulose and pectin in onion epidermis cell wall: A polarized FT-IR study

The organization of polysaccharides in plant cell walls is important for the mechanics of plant cells. Spectral analysis of cell walls by polarized IR can reveal polysaccharide organization, but may be complicated by dipoles not aligned with the backbone. For instance, analysis of uniaxially-aligned cellulose Iβ film revealed that the dipole transition vector of the 1160 cm^?1 band involving stretch vibrations of glycosidic C1–O–C4 linkages is approximately at 30° with respect to the backbone of the cellulose chain, because of coupling with C5–O–C1 bonds in the six-membered rings. In the case of homogalacturonan, the dipole transition vector of the ester carbonyl group vibration (ν_C=O, 1745 cm^?1) is expected to be nearly normal to the homogalacturonan backbone. Using this information and the dichroism equation, the change in net orientation of cell wall polymers upon mechanical stretch was determined by polarized IR analysis. Never-dried abaxial outer epidermal cell walls of the second scale of onion bulb were mechanically stretched along longitudinal or transverse directions with respect to the long axis of the cells and then dried while under mechanical stretch. The average orientations of both 1160 and 1745 cm^?1 vibration transition dipoles were rotated by ~5° and ~4°, respectively, along the stretch direction from their initial random distributions upon longitudinal strain by 14%; and by ~4° and ~3°, respectively, upon transverse strain by 12%. These results imply that both cellulose microfibrils and pectins in the cell wall are passively realigned along the stretch direction by external mechanical force. The analytical methodology developed here will be useful to study how cell wall polymers might reorganize during cell wall growth and development.     

On minimizers for the isotropic–nematic interface problem

In this paper, we investigate the structure and stability of the isotropic-nematic interface in 1-D. In the absence of the anisotropic energy, the uniaxial solution is the only global minimizer. In the presence of the anisotropic energy, the uniaxial solution with the homeotropic anchoring is stable for \(L_2<0\) and unstable for \(L_2>0\). We also present many interesting open questions, some of which are related to De Giorgi conjecture.     

Synthesis of SMND-309, a derivate of salvianolic acid B

(E)-2-(6-((E)-2-carboxyvinyl)-2,3-dihydroxyphenyl)-3-(3,4-dihydroxyphenyl) acrylic acid, designated SMND-309, was synthesized starting from 2-hydroxy-3-methoxybenzaldehyde in 12 steps and with an overall yield of 44%. The synthetic key features were the conversion of aryl aldehyde into aryl acetic acid for one-carbon extended, the Perkin condensation, and the Heck coupling for construction of α,β-unsaturated ester.     

Acid–base and coordination properties of <Emphasis Type="Italic">Meso</Emphasis>-substituted porphyrins in nonaqueous solutions

Acid–base and coordination properties of alkyl and aryl meso-substituted porphyrins are studied spectrophotometrically in nonaqueous solutions. It is found that the nature of the substituent greatly affects the basicity of ligands for porphyrins characterized by a flat structure of macrocycle. The electronic effects of substituents have a much weaker influence on the kinetics of complexing. These effects could be due to the opposite orientation of some factors: an increase in the basicity and stability of the N–H bonds of porphyrin reaction centers. Dissociation constants pK _b of the cationic forms of meso-substituted derivatives of porphyrin are measured. The values of pK _b are in good agreement with classic concepts of the nature of substituents, particularly those indirectly included in the macrocycle through phenyl buffer rings.     

Elemental Analysis of Stone Fruits by Inductively Coupled Plasma Mass Spectrometry and Direct Mercury Analysis

This study reports the concentrations of eight trace essential (Zn, Mn, Cu, Ni, Cr, Co, V, and Se) and four toxic elements (Pb, As, Cd, and Hg) in commonly consumed stone fruits from South Korea. The samples were digested by microwave-induced combustion and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of mercury were analyzed by direct mercury analysis (DMA). The analytical techniques were validated by linearity, limits of detection and quantification, precision, recovery, and for accuracy by analyzing a spinach leave-certified reference material; satisfactory results were obtained in all cases. The concentrations of essential trace elements varied considerably among the stone fruits. Generally stone fruits contained comparatively high concentrations of Zn (0.946 to 7.86?µg/g) and Mn (below the limit of detection to 1.66?µg/g), while lower contents of Cu (0.214 to 1.24?µg/g), Cr (0.032 to 0.114?µg/g), Ni (0.006 to 0.091?µg/g), Co (0.004 to 0.016?µg/g), V (below the limit of detection to 0.023?µg/g), and Se (0.0002 to 0.005?µg/g) were obtained. The concentrations (µg/g) of toxic metals were 0.007 (peach) to 0.016 (cherry) for Pb, 0.001 (plum) to 0.007 (cherry) for As, 0.002 (apricot and cherry) to 0.003 (peach) for Cd, and 0.0003 (peach) to 0.0016 (jujube) for Hg. The values for the estimated dietary intakes, target hazard quotients, and hazard indices were lower than the recommended safety limits by World Health Organization. Therefore, the analyzed stone fruits were deemed to be safe for human consumption.     

Signal-Induced Release of Guests from a Photolatent Metal–Phenolic Supramolecular Cage and Its Hybrid Assemblies

The coordination chemistry of plant polyphenols and metal ions can be used for coating various substrates and for creating modular superstructures. We herein explored this chemistry for the controlled release of guests from mesoporous silica nanoparticles (MSNs). The selective adsorption of tannic acids (TAs) on MSN silica walls opens the MSN mesoporous channels without disturbing mass transport. The channel may be closed by the coordination of TA with Cu^II ions. Upon exposure to light, photolysis of Trojan horse guests (photoacid generators, PAGs) leads to acid generation, which enables the release of payloads by decomposing the outer coordination shell consisting of TA and Cu^II. We also fabricated a modular assembly of MSNs on glass substrates. The photoresponsive release characteristics of the resulting film are similar to those of the individual MSNs. This method is a fast and facile strategy for producing photoresponsive nanocontainers by non-covalent engineering of MSN surfaces that should be suitable for various applications in materials science.     

Ternary and binary copper(II) complexes: synthesis,characterization, ROS-inductive,proteasome inhibitory,and anticancer properties

Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H₂O, [Cu(phen)(L-leu)Cl]·4½H₂O, and [Cu(phen)(L-tyr)Cl]·3H₂O, and four binary copper(II) complexes, [Cu(phen)Cl₂]_, Cu(L-phe)₂·½H₂O, Cu(L-leu)₂·½H₂O, and Cu(L-tyr)₂·H₂O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl^- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl₂, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin.