Synthesis and Crystal Structure of [Ni(II)(L)(py)_3]·(py)

1 INTRODUCTION Schiff bases and their metal complexes are useful reagents in organic synthesis[1], and they have exhi- bited some biological activities as anticancer and antitumor drugs[2]. The crystal structures and physi- cal and chemical properties of many Schiff bases and their transition metals complexes have been re- ported[3~5]. Further interest in the coordination che- mistry of nickel(II) arises from the role of these complexes in several catalytic reactions, such as electrocat…     

Unusual Disordering of Potassium Ions in the Structures of Cluster Rhenium Thiohalides K3[Re6S7Br7] and K4[Re6S8Cl6]

New cluster compounds — rhenium and potassium thiohalides K₃Re₆S₇Br₇ (I) and K₄Re₆S₈Cl₆ (II) — have been synthesized. Their crystal structures have been determined by single crystal X-ray diffraction. The compounds are monoclinic; (I): space group P2₁/c, a = 9.32(1) Å, b = 13.528 Å, c = 12.413 Å, β = 110.21°, Z = 2, R = 0.038; (II): space group C2/m, a = 10.614 Å, b = 17.268 Å, c = 10.448 Å, β = 110.755°, Z = 2, R = 0.042. In both structures, the potassium ions are considerably distorted. The occupancies of the potassium sites are 0.17-0.34 (I) and 0. 01-0.26 (II), correlating well with the coordination numbers (c.n. 7-10 and 2-7 for I and II, respectively). In I, adjacent positions of potassium atoms are aggregated into discrete tetrahedral and angular clusters; in II, the individual (four-and six-membered) cyclic clusters of potassium sites are present along with bent chains of vertex-and edge-sharing tetrahedral “potassium clusters.” The shortest K-K distances in these “clusters” vary from 1.31 Å to 1.54 Å (I) and from 0.66 Å to 1.65 Å (II). The “instability” of the potassium site suggests that I and II are ion conductors.Original Russian Text Copyright © 2004 by S. F. Solodovnikov, S. S. Yarovoi, Yu. V. Mironov, A. V. Virovets, and V. E. Fedorov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 909–917, September–October, 2004.     

Thermal Study of Surfactant and Anion Adsorption on Clinoptilolite

The mechanism of surfactant adsorption on various forms of clinoptilolite was studied by DTA, TG and DTG analyses. The examined series of surfactant modified clinoptilolite (SMC) was previously prepared by the adsorption of the surface-active oleylamine on Ca²⁺, Na⁺, H⁺ and mechanochemically treated forms of clinoptilolite. The oleylamine was most strongly adsorbed on H⁺-forms of clinoptilolite due to the largest number and strength of adsorption sites. The surfactant adsorption mechanism on H⁺-form of clinoptilolite was studied by recording the series of variously surfactant-loaded samples. The products of sulphate, dihydrogenphosphate and hydrogenchromate adsorption on SMC were analyzed by DTA, TG and DTG in order to investigate the mechanism of anion adsorption.This revised version was published online in November 2005 with corrections to the Cover Date.     

Identification of<Emphasis Type="Italic"> N</Emphasis>-glycosylation sites of the murine neural cell adhesion molecule NCAM by MALDI-TOF and MALDI-FTICR mass spectrometry

Mass spectrometry has been shown in recent years to be a powerful tool to determine accurate molecular masses and sequences of peptides and proteins and post-translational modifications such as glycosylation, phosphorylation, and sulfation. For glycosylation, it has been increasingly recognized to be of pivotal importance to identify whether potential glycosylation sites are actually modified by glycans, because functions of proteins may be modulated or depend on the presence of glycans at specific sites. Several recent reports have established that mass spectrometric techniques such as matrix-assisted laser desorption/ionization or electrospray ionization mass spectrometry (MALDI-TOF or ESI-MS, respectively) with or without preceding HPLC and in combination with PNGase F treatment are suited to analyze whether consensus sequences for N-glycosylation are glycosylated or not. Here we report the mass spectrometric analysis of the six potential N-glycosylation sites of the neural cell adhesion molecule NCAM from adult mouse brain. Unmodified peptides and glycopeptides each carrying a single glycosylation site were generated from NCAM by AspN and trypsin treatment and submitted to reversed-phase HPLC with or without prior enzymatic release of N-glycans. The resulting peptides were analyzed by MALDI-TOF-MS. In addition, high-resolution Fourier transform–ion cyclotron resonance (MALDI-FTICR) mass spectrometry was performed after in-gel deglycosylation and subsequent trypsin digestion. By using these procedures all six consensus sequences were shown to be glycosylated; the observation of an unmodified peptide with the consensus sequence N-1 indicates only partial glycosylation at this site.Abbreviations amu atomic mass units - AspN endoproteinase AspN - CAM cell adhesion molecule - ESI electrospray ionization - FTICR Fourier transform–ion cyclotron resonance - IgSF immunoglobulin superfamily - MALDI-TOF matrix-assisted laser desorption ionization–time of flight - MS mass spectrometry - NCAM neural cell adhesion molecule - PNGase F peptide-N ⁴-(N-acetyl--glucosaminyl)asparagine amidase - PSA polysialic acid - TFA trifluoroacetic acid     

10种2-[(N-取代芳胺基)羰基]苯甲酸与Cr(Ⅲ)的配合物研究

Complexes of Cr(Ⅲ) with ten of substituted phthalanilic acids have been prepared and characterized by the basis of elemental analysis, infrared and electronic spectra and magnetic susceptibility. The ligand field parameters, e.g. 10Dq, LFSE, B, β, λ, g-have been evaluated from the spectral and magnetic data for all the complexes. The results show that coordination occurs though two oxygen atoms in amido and hydroxy of carboxylates and the complexes have octahedral structure.     

Highly selective fenuron-imprinted polymer with a homogeneous binding site distribution prepared by precipitation polymerisation and its application to the clean-up of fenuron in plant samples

In the present study, two different imprinted polymers were synthesised by precipitation polymerisation using methacrylic acid (MAA) or 4-vinylpyridine (VP) as monomer and fenuron (FEN, a phenylurea herbicide) as template. After template removal, their ability to recognise fenuron was evaluated and the optimum loading, washing and elution conditions were established. From this study, it was concluded that imprinted binding sites were not formed in the vinylpyridine-based polymer. However, methacrylic acid-based polymer was able to recognise fenuron with high affinity and to selectively retain it from a mixture of several phenylurea herbicides. In addition, different rebinding experiments were carried out and the experimental binding isotherms were fitted to the Langmuir-Freundlich (LF) isotherm in order to assess the binding site distribution. It was concluded that the methacrylic acid-based polymer possesses a homogeneous binding site distribution and permits to achieve quantitative recoveries in a wide concentration range in molecularly imprinted solid-phase extraction (MISPE) processes. The developed MISPE procedure using methacrylic acid-based polymeric micro-spheres was evaluated for the trace-enrichment and clean-up of fenuron from plant sample extracts.     

Sn改性TS-1分子筛催化草酸二甲酯和苯酚酯交换合成草酸二苯酯

 研究了Sn改性TS-1催化剂催化苯酚和草酸二甲酯（DMO）酯交换合成草酸二苯酯(DPO)反应。以Sn改性TS-1为催化剂时，Sn活性中心和Lewis酸中心协同作用催化苯酚和DMO酯交换合成DPO反应。因为Sn的加入，在保持MPO和DPO高选择性的同时，DMO转化率显著提高。而且Sn活性中心有利于MPO歧化反应生成DPO，从而大大提高了DPO的选择性。但是，当Sn负载量大于2％时，SnO2由均匀分布在TS-1表面改变为以晶体状态存在，从而导致DMO转化率的大幅降低。     

[~3H] TYROSINE BINDING TO PLASMA MEMBRANE PREPARATION OF RAT CORPORA LUTEA

Plasma membrane preparations of rat corpora lutea have been incubated with [~3H]tyrosine. [~3H]-tyrosine binding sites are demonstrated and Scatchard analysis shows that there exist two types of binding sites, one with high affinity and low capacity, the other with low affinity and high capacity. The kinetics studies demonstrate that the [~3H]tyrosine binding to the two types of binding sites is reversible and the speed of binding to the high affinity type is faster than that to the low affinity type. The analysis of the chemical structure of tyrosine analogues and related compounds with respect to the specificity of the binding sites reveal that both types of binding sites show specificity, but the specificity of the high affinity sites is higher than that of the low affinity sites. The relations of tyrosine structure to binding processing and to tyrosine inhibitory action on hCG-induced progesterone production are discussed. It is suggested that the high affinity binding sites might be regarded as "ty     

HYDROGENATION OF CO_2 OVER A YBa_2Cu_3O_(6～7) CATALYST

研究了ＹＢａＣｕ３Ｏ６～７超导催化剂上ＣＯ２的加氢制醇反应。考察了温度、压力和空速等条件对催化剂反应性能的影响。反应的主要产物是甲醇、ＣＯ和少量甲醚。利用ＸＰＳ、ＸＲＤ和ＡＦＭ等技术对催化剂的结构、铜的存在状态和反应活性位进行表征发现，在反应过程中，ＹＢａ２Ｃｕ３Ｏ６～７由ｏｒｔｈｏｍｂｉｃ相转变为ｔｅｔｒａｇｏｎａｌ相。反应活性位可能是Ｃｕ（Ｉ）物种。反应后催化剂颗粒的分散程度明显提高     

Structural properties and potential reactivity of substituted 3- aroyldithiocarbazates

A series of substituted 3-aroyldithiocarbazates has been synthesized and studied. The corresponding acid dissociation constants have been determined potentiometrically. Semiempirical PM3 molecular orbital calculations suggest the existence of several tautomeric forms of the compounds. Geometrical parameters, proton affinities, and static reactivity indices have been examined. Structural properties and protonation sites are well described by calculations. The strong correlations between the pK _a values and the Hammett constants as well as the N(3) calculated proton affinities indicate that the N(3) atom is the most probable protonation site. The thermodynamics of the protonation process are mainly controlled by HOMO-LUMO rather than electrostatic interactions. According to PM3 results, 3-aroyldithiocarbazic acid should be quite stable in the gas phase, while a mechanism for its decomposition in solution is proposed.