The construction of versatile azido-bridged Schiff base Copper(II) complexes with xanthine oxidase inhibitory activity

Structural Chemistry - Three new versatile azido-bridged Schiff base Copper(II) complexes, [Cu2(L1)2(μ1,1-N3)2]·2CH3OH (1), [Cu(L2)(μ1,3-N3)] n (2), and [Cu2(L3)(μ1,1-N3)2(N3)]2...     

Organophosphine/phosphite‐stabilized silver(I) complexes bearing N‐acetylbenzamide ligand: synthesis,characterization and potential application in metal organic chemical vapor deposition

New N‐silver(I) acetylbenzamide complexes of type L_n?AgNC₉H₈O₂ (L = PPh₃; n = 1, 2a; n = 2, 2b; n = 3, 2c; L = P(OEt)₃; n = 1, 2d; n = 2, 2e; n = 3, 2f) were prepared. These complexes were obtained in high yields and characterized by elemental analysis, ¹H NMR, ¹³C{H} NMR, ³¹P{H} NMR and IR spectroscopy, respectively. The molecular structure of 2b has been determined by X‐ray single‐crystal analysis in which the silver atom is in a distorted tetrahedral geometry and crystallizes as cis–trans. New N‐silver(I) acetylbenzamide complexes have a four‐membered ring, which could influence their chemical and physical properties and modulate volatility. Metal organic chemical vapor deposition experiments were carried out successfully at 400°C and 450°C using 2e as precursor for the deposition of silver films, respectively. The high‐purity silver film obtained at 400°C is dense and homogeneous. Copyright © 2012 John Wiley & Sons, Ltd.     

Theoretical study of the thermal rearrangement of chloromethylsilanes, and its mechanism

The thermal rearrangement reactions of chloromethylsilane, (chloromethyl)dimethylsilane, and (chloromethyl)vinylsilane have been studied by use of the density functional theory method at the B3LYP/6-311G(d, p) level. The structures of the reactants, transition states, and the products were determined and fully optimized. The geometries of the different stationary points and the harmonic vibrational frequencies were calculated at the same level. The results showed that thermal rearrangement of the chloromethylsilanes occurred via one pathway. The chlorine atom migrated from the carbon atom to the silicon atom, and the hydrogen atom migrated simultaneously from the silicon atom to the carbon atom through a double-three-membered-ring transition state, forming methylchlorosilane, trimethylchlorosilane, and vinylmethylchlorosilane. The energy barriers of the three rearrangements calculated at the B3LYP/6-311G(d, p) level were 217.4, 201.6, and 208.7 kJ mol^?1, respectively. The effects of alkyl substituents on silicon atom are discussed. Changes of thermodynamic functions, equilibrium constant, and reaction rate constant were calculated in accordance with Eyring transition-state theory over the temperature range 400–1,500 K.     

Homogenization of layered elastoplastic composites: Theoretical results

Exact closed-form solutions are derived that completely characterize the effective behavior of a composite material made of elastic-perfectly plastic parallel plane layers perfectly bonded together. The derivation is framed within a rigorous theory of homogenization for elastoplastic composites, and based on the fundamental fact that the in-plane part of the strain tensor and the out-of-plane part of the stress tensor are uniform throughout the composite provided no free-edge effects occur. The obtained expressions are coordinate-free and valid in the general anisotropic case. As an example, a layered composite material with isotropic constituents is examined in detail.     

Discontinuous crack-bridging model for fracture toughness analysis of nacre

Studying the structure–property relation of biological materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of advanced biomimetic materials. In this paper, we present a microstructure-based fracture mechanics model to investigate the toughening effect due to the crack-bridging mechanism of platelets. Our theoretical analysis demonstrates the crucial contribution of this mechanism to the high toughness of nacre. It is found that the fracture toughness of nacre exhibits distinct dependence on the sizes of platelets, and the optimized ranges for the thickness and length of platelets required to achieve higher fracture toughness are given. In addition, the effects of such factors as the mechanical properties of the organic phase (or interfaces), the effective elastic modulus of nacre, and the stacking pattern of platelets are also examined. Finally, some guidelines for the biomimetic design of novel materials are proposed based on our theoretical analysis.     

A theoretical study of some problems on low-noise pyroelectric detector-amplifier systems

The configurations of the coupling network, which can effectively aecrease the effect of the noise sources within the amplifier on the equivalent input noise of the whole pyroelectric detector-amplifier system, are studied. The influences of feedback upon the noise properties of the basic amplifiers are analyzed. The procedures of designing low-noise pyroelectric detector-amplifier systems are followed.     

稀土化合物RX的晶场参数分析

本文对NaCl型结构的稀土化合物RX(X=N,P,As,Sb,Bi)的晶场参数B₄⁰的实验值进行了分析。在此基础上我们提出一个新的利用简单点电荷模型计算RX晶场参数B₄⁰值的关系式:B₄⁰=k₃(B₄⁰)_p+c₃。用此关系式我们确定了一系列RX的晶场参数B₄⁰值,结果与实验值符合很好。对关系式的含义本文也作了充分讨论。 关键词：