Synthesis and binding studies of novel thiacalixpodands and bisthiacalixarenes having O,O″-dialkylated thiacalix[4]arene unit(s) of 1,3-alternate conformation

A series of thiacalixpodands and bisthiacalixarenes with imine units have been prepared by condensation of O,O″-bis(2-aminoethyl)-O′,O?-dipropyl-p-tert-butylthiacalix[4]arene of 1,3-alternate conformation with different aromatic (di)aldehydes. The molecules derived from pyridine-2-carbaldehyde and -2,6-dicarbaldehyde quantitatively extract silver ion from aqueous into organic phase with complete selectivity over other metal ions (Na⁺, K⁺ and Cs⁺) under neutral conditions. The former compound forms a 1:2 (L:M) complex with silver ion as proved by NMR spectroscopy, Job’s plot and X-ray crystallography.     

The full 2p-h tda and other self-energy approximants: a comparative investigation

A super-operator formulation for decoupling symmetry blocks of the full 2p-h TDA electron propagator matrix is presented, accuracy is explored using the full 2p-h TDA overlap amplitudes to calculate relative ionization intensities for N₂ and H₂O. The effect of excluding orbitais on IPs and relative ionization cross sections is reported.     

Synthesis,characterization, DNA binding and cleavage activity of homoleptic zinc(II) β-oxodithioester chelate complexes

New homoleptic zinc(II) complexes, [Zn(L)₂], where L = methyl-3-hydroxy-(3-pyridyl)-2-propenedithioate L1 1, and methyl-3-hydroxy-(4-pyridyl)-2-propenedithioate L2 2, have been synthesized and characterized by elemental (C, H, and N) analysis, ESI-MS, and (IR, UV–vis, NMR) spectroscopy; the structure of 1 has been deduced by X-ray crystallography. The DNA binding and cleavage activity of the complexes have been studied. The cleavage potential of pBR322 DNA by 1 and 2 has been checked. Complex 1, which contains nitrogen of the pyridine group in the 3-position enhances DNA cleavage potential in the presence of ascorbic acid; however, the complex is protective against DNA cleavage in the presence of DMSO or H₂O₂. Also, 1 causes cytotoxicity against the MCF-7 breast cancer cell line. The efficient cytotoxic activity and DNA cleavage ability of 1 in the presence of ascorbic acid shows its potential anticancer properties and the need for further investigations of its potential as an anticancer drug.     

Synthesis of p-tert-Butylcalix[4] Arenes with Diester Bridge Spanning the 1,3-(Distal) Positions on the Lower Rim

Abstract

p-tert-Butylcalix[4]crown ether esters have been synthesized in good yield using two synthetic methods.     

Relationships of labile pool of Mn with some general soil properties and extractable soil Mn contents

Labile pool (E-value) of Mn and extractable soil Mn content using six multinutrient extractants were estimated in fifty surface (0–15 cm) soil samples. Labile pool of Mn was poorly correlated to the general soil properties and modified Olsen’s-; 0.01 M CaCl₂- and 1 M MgCl₂-extractable Mn contents but it was positively and significantly correlated to diethylene triamine pentaacetic acid (DTPA), pH 7.3; ammonium bicarbonate + DTPA (pH 7.6); and Mehlich-3-extractable soil Mn contents. The multinutrient extractants involving only simple salt solutions were not useful to assess the availability of Mn in soils.     

Synthesis of New Macrocyclic Polyaza Compounds Containing 1-Methylpyrazole

New macrocyclic polyaza compoundscontaining the 1-methylpyrazole moiety are synthesizedin high yield by [2+2]dipodal condensation andreduction. The ring contracted structure of the Schiffbase has been elucidated by NMR. Two of thesemacrocycles form dinuclear complexes with copper andsilver. Macrocyclic Schiff base 5a extracts74.5% silver from aqueous to organic phase.     

Symmetry groups and similarity solutions for the system of equations for a viscous compressible fluid

Here, using Lie group transformations, we consider the problem of finding similarity solutions to the system of partial differential equations (PDEs) governing one-dimensional unsteady motion of a compressible fluid in the presence of viscosity and thermal conduction, using the general form of the equation of state. The symmetry groups admitted by the governing system of PDEs are obtained, and the complete Lie algebra of infinitesimal symmetries is established. Indeed, with the use of the entailed similarity solution the problem is transformed to a system of ordinary differential equations(ODEs), which in general is nonlinear; in some cases, it is possible to solve these ODEs to determine some special exact solutions.     

An explorative study on diarylquinoline-based inhibitor targeting Enterococcus faecium MurF

Structural Chemistry - Enterococcus faecium MurF (EfMurF) enzyme catalyzes the addition of d-alanyl-d-alanine to form murein UDP-N-acetylmuramoyl-pentapeptide. This is the last cytoplasmic step of...     

Determination of the 15N chemical shift anisotropy in natural abundance samples by proton-detected 3D solid-state NMR under ultrafast MAS of 70 kHz

Chemical shift anisotropy (CSA) is a sensitive probe of electronic environment at a nucleus, and thus, it offers deeper insights into detailed structural and dynamic properties of different systems, for example, chemical, biological, and materials. Over the years, massive efforts have been made to develop recoupling methods that reintroduce CSA interaction under magic angle spinning (MAS) conditions. Most of them require slow or moderate MAS (≤20 kHz) and isotopically enriched samples. On the other hand, to the best of the authors' knowledge, no ¹³C or ¹⁵N CSA recoupling schemes at ultrafast MAS (≥60 kHz) suitable for cost-effective natural abundant samples have been developed. We present here a proton-detected 3D ¹⁵N CS/¹⁵N CSA/¹H CS correlation experiment which employs ¹H indirect detection for sensitivity enhancement and a γ-encoded -symmetry-based CSA recoupling scheme. In particular, two different symmetries, that is, R8³₇ and R10⁴₉, are first tested, in a 2D ¹⁵N CSA/¹H CS version, on [U-¹⁵N]-L-histidine·HCl·H₂O as a model sample under 70 kHz MAS. Then the 3D experiment is applied on glycyl-L-alanine at natural abundance, resulting in site-resolved ¹⁵N CSA lineshapes from which CSA parameters are retrieved by SIMPSON numerical fittings. We demonstrate that this 3D R-symmetry-based pulse sequence is highly robust with respect to wide-range offset mismatches and weakly dependent to rf inhomogeneity within mis-sets of ±10% from the theoretical value.