Bifunctional Calix[4]arene Sensor for Pb(II) and Cr2O7 2− Ions

A readily available chromionophore 5,11,17,23-tetra-tert-butyl-25,27-bis(hydrazidecarbonylmethoxy)-26,28-dihydroxycalix[4]arene (HCC4) was employed as a chromogenic sensing probe selective for Pb(II) and Cr₂O₇ ^2? ions among a series of various ions such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) as well as Cr₂O₇ ^2?, CH₃CO₂ ^?, Br^?, Cl^?, F^?, I^?, ClO₄ ^? and NO₃ ^? that have been examined by UV-visible and fluorescence spectroscopic techniques. The HCC4 in DCM-MeCN system forms 2:1 (ligand-metal) complex with Pb(II). It also shows 2:1 stoichiometry with Cr₂O₇ ^2?. The complexation phenomenon has been confirmed by FTIR spectroscopy that favors the selective nature of HCC4 with Pb(II) and Cr₂O₇ ^2?. Thermal gravimetric analysis (TGA) also supports its utility in drastic conditions.     

Conjugated polymer-wrapped carbon nanotubes: physical properties and device applications

The aim of this article is to present an overview about the preparation method and physical properties of a new hybrid system consisting of single-walled carbon nanotubes (SWNTs) wrapped by conjugated polymers. The technique firstly demonstrated in 2007 has attracted great interest because of the high purity of the resulting semiconducting SWNTs and the possibility of applying them in electronic devices. Here, we will review recent progresses regarding the preparation of these nano-hybrids, their photophysical properties and application in field-effect transistors and photovoltaic devices.     

Special jordan H*-triple systems

This work, jointly with [9], completes the structure theory and classification of the Jordan H ^*- triple systems. The problem of describing the Jordan H ^*-triple systems is reduced in [5] to that of describing the topologically simple ones. Ruling out the finite-dimensional case, we have that any of these H ^*-triples has an underlying triple system structure of quadratic type (and these can be fully described), or it is the H ^*-triple system associated to the odd part of a topologically simple Z₂-graded Jordan H ^*-algebra, whose classification is given in [13].     

Level Structures on the Weierstrass Family of Cubics

Let W → 𝔸 ² be the universal Weierstrass family of cubic curves over ?. For each N ≥ 2, we construct surfaces parameterizing the three standard kinds of level N structures on the smooth fibers of W. We then complete these surfaces to finite covers of 𝔸 ². Since W → 𝔸 ² is the versal deformation space of a cusp singularity, these surfaces convey information about the level structure on any family of curves of genus g degenerating to a cuspidal curve. Our goal in this note is to determine for which values of N these surfaces are smooth over (0, 0). From a topological perspective, the results determine the homeomorphism type of certain branched covers of S ³ with monodromy in SL₂ (?/N).     

Single-Molecule Observation of Intermediates in Bioorthogonal 2-Cyanobenzothiazole Chemistry

We report a single-molecule mechanistic investigation into 2-cyanobenzothiazole (CBT) chemistry within a protein nanoreactor. When simple thiols reacted reversibly with CBT, the thioimidate monoadduct was approximately 80-fold longer-lived than the tetrahedral bisadduct, with important implications for the design of molecular walkers. Irreversible condensation between CBT derivatives and N-terminal cysteine residues has been established as a biocompatible reaction for site-selective biomolecular labeling and imaging. During the reaction between CBT and aminothiols, we resolved two transient intermediates, the thioimidate and the cyclic precursor of the thiazoline product, and determined the rate constants associated with the stepwise condensation, thereby providing critical information for a variety of applications, including the covalent inhibition of protein targets and dynamic combinatorial chemistry.     

A new aliphatic ester of hydroxysalicylic acid from fermented Carica papaya L. preparation with a potential hair growth stimulating activity

Abstract

An aliphatic ester of hydroxysalicylic acid (6), reported for the first time from a natural source in addition to five known compounds were isolated from the fermented Carica papaya L. preparation, a commercialized functional food. The known compounds were identified as 5-hydroxymethylfurfuraldehyde (1), trans-caffeic acid (2), butyl 4-hydroxybenzoate (butylparaben) (3), lycopene (4), benzyl isothiocyanate (5). Compounds 1 and 3 were reported for the first time from Papaya fruits through this study. The new compound showed a moderate antioxidant activity and a potent hair growth stimulating activity in vitro.     

Improving the visible-light photocatalytic activity of SnO<Subscript>x</Subscript>·SiO<Subscript>2</Subscript> glass systems by introducing SnO<Subscript>x</Subscript> nanoparticles

Tin silicate glass without SnO_x nanoparticles (SiO₂·SnO_x), a silica glass containing only SnO_x nanoparticles (SiO₂·SnO_xNP) and the improved product, which combines the tin silicate glass with SnO_x nanoparticles (SiO₂·SnO_x·SnO_xNP) was prepared. For the structural analysis ¹¹⁹Sn Mössbauer spectroscopy and X-ray diffraction were applied. The ¹¹⁹Sn Mössbauer spectra showed that the SiO₂·SnO_x·SnO_xNP sample had the largest Sn^II content (12.0%). It also had an outstanding methylene blue degradation with the first-order rate value with (18?±?2) × 10^?3 min^?1 with visible light irradiation.     

Phase behavior and chain dynamics of elastin-like peptides versus amino acid sequences

Journal of Thermal Analysis and Calorimetry - Elastin fibrillogenesis is conditioned by multiple self-assembly processes. Previous studies have evidenced the crucial influence of amino acid...     

Synthesis and X-ray structure of tetrakis[μ-(3,4-dimethoxy-α-β-dihydrocinnamato)] dimethanoldicopper(II)

The synthesis, magnetic, and structural properties of the title compound are reported. The crystals are triclinic, space groupP¯1, witha=15.084(2),b=11.820(1),c=7.5253(7) Å, =71.50(1),=77.61(1), =68.68(1)° andZ=1; the structure was solved by Patterson and Fourier methods and refined toR 0.0351 for 4147 observed reflections. The content of the unit cell consists of a centrosymmetrical copper acetate-like molecule in which each copper can be described as square-pyramidally surrounded by four carboxylic oxygens in the basal plane [1.955(2)–1.970(2) Å], one methanolic oxygen in the apical site [2.206(2) Å] and a CuCu interaction of 2.612(5) Å at a sixth position of a distorted octahedron. The dimers are packed by means of hydrogen bonds formed between the methanolic OH group and the carboxylic O(2) atom of one adjacent complex and by normal Van der Waals contacts. The subnormal magnetic moment, characteristic of exchange interactions between the two copper(II) ions, and the energy of the d-d band observed are consistent with the reported dinuclear copper(II) acetate-like structure.