A New Dinuclear Copper (II) Complex of a Bis‐macrocyclic Ligand: Synthesis,Characterization, Crystal Structure and Magnetic Properties

A new dinuclear Cu(II) complex, [Cu₂L(N₃)₂](ClO₄)₁.₅ (OH)_4.5 · 2H₂O 0.5C₂H₅OH (1), of a bis‐macrocyclic ligand, 2,6‐bis(l,4,7,10‐tetraazacyclododecan‐10‐ylmethyl)‐methoxybenzene (L), has been synthesized, characterized and structurally determined by X‐ray diffraction analysis. Complex 1 crystallizes in orthorhombic crystal system, Pca2(l) space group with a = 1.5371(3), b = 1.6641(3), c = 3.0950(6) nm, V = 7.917(3) nm³, F_w = 904.62, Z=8, D_c= 1.529 g/cm³ and final R = 0.0568, wR = 0.1406 for 10410 observed reflections with I≥2σ (I). Both Cu(II) centers in the structure are coordinated by four nitrogen atoms of 1,4,7, 10‐tetraazacyclododecane (cyclen) and a nitrogen donor of the axial azide anion. Each Cu(II) center is in a square‐pyramidal coordination environment, and the intra‐and nearest inter‐molecular Cu? Cu nonbonding distances are 0.9855 and 0.7298 nm, respectively. Variable temperature magnetic susceptibility measurements in the range of 4.2–300 K indicate mat there exists weak intra‐ and inter‐molecular antiferromagnetic coupling between the Cu(II) centers with 27= ?4.2 cm^?1 and Θ = ?0.47 K.     

The Magnetic Field Effect on the Polymerization of Styrene in Supercritical Carbon Dioxide

Over the past decade there has been a growing interest in using supercritical fluids (SCFs) to promote reactions and to replace hazardous solvents with environmentally benign solvents, such as supercritical CO2 and H2O. Many reactions in SCFs have been studied1, including polymerization in scCO22. It is known that a small change in the pressure near critical point of a fluid causes a significant change in density-dependent properties such as the solubility parameter, viscosity, and dielect…     

Hydrothermal synthesis, structure and quantum chemistry of transition metal complex supported by metal-oxo cluster [(Ni(phen)22 (ξ-Mo8O26)]

A nickel-1,10-phenanthroline complex supported on an octamolybdate, [(Ni(phen)_{2 2}(ξ-Mo₈O₂₆)], has been hydrothermally synthesized with MoO₃, H₂MoO₄, Ni(OAc)₂ 6H₃O and 1,10-phenathroline (1,10-phen) as raw materials. The crystals of the compound belong to monoclinic P2₁/n space group,a = 1.2952(2),b = 1.6659(10),c = 1.3956(12) nm, β =106.273(8)°,V = 2.8906(5) nm³,Z = 2. 5604 observable reflections (I >2σ(I)) were used for structure resolution and refinements to converge to finalR ₁ = 0.0414,wR ₂ = 0.0815. The result of structure determination shows that the compound contains octamolybdate possessing a novel structure type (named as ξ-isomer). The feature of ξ-[Mo₈O₂₆]^4- is that it is composed of Mo₆O₆ ring and two MoO₆ octahedral located at cap positions on opposite faces. The Mo₆O₆ ring contains two octahedral and four trigonal-bipyramidal Mo^VI atoms. Each ξ-[Mo₈O₂₆]^4- unit is bonded with two [Ni(phen)₂]²⁺ through terminal oxygen atoms of octahedral and neighbouring trigonal-bipyramidal Mo atom in the Mo₆O₆ ring. IR and UV-Vis spectra of the compound were measured and its electronic structure was studied by EHMO method.     

Co(H2O)62+/3+体系电子转移反应动力学的理论研究

A theoretical scheme is presented which is based on an activation model for calculating the rate of the electron- exchange reaction between transition metal complexes in aqueous solution and applies to Co(H2O)6 2+/3+ electron transfer system. The activation parameter and activation energy of the system are obtained via the activation model. The slopes of the potential energy surfaces (curves) of the reacting system at the separated reactants are calculated from the fitted potential energy curves. The coupling matrix element is determined by using the perturbation theory and numerical integral method. Theoretical rate constants are obtained for the system at both UHF/6-311G and UMP2/6-311G levels. The agreement of the theoretical results with experimetal values is excellent. This fact indicates the scheme proposed is feasible and accurate in studying the self- exchange eletron transfer reaction.     

Main Q-eigenvalues and generalized Q-cospectrality of graphs

Let Q ^G denote the signless Laplacian matrix of a graph G. An eigenvalue μ of Q ^G is said to be a main Q-eigenvalue of G if μ has an eigenvector which is not orthogonal to an all-ones vector e. We give some basic properties of main Q-eigenvalues. For a graph G of order n, G is called Q-controllable if G has n distinct main Q-eigenvalues. We show that a graph H is generalized Q-cospectral with a Q-controllable G if and only if H is Q-controllable and there exists a unique rational orthogonal matrix R such that R _e = e, Q _H = R ^? Q _G R.     

An Overview of Infrared Spectroscopy Based on Continuous Wavelet Transform Combined with Machine Learning Algorithms: Application to Chinese Medicines,Plant Classification,and Cancer Diagnosis

Abstract

Infrared spectroscopy has been a workhorse technique for materials analysis and can result in positively identifying many different types of material. In recent years there have been reports using wavelet analysis and machine learning algorithms to extract features of Fourier transform infrared spectrometry (FTIR). The machine learning algorithms contain back-propagation neural network (BPNN), radial basis function neural network (RBFNN), and support vector machine (SVM). This article reviews the important advances in FTIR analysis employing a continuous wavelet transform (CWT) and machine learning algorithms, especially in the applications of the method for Chinese medicine identification, plant classification, and cancer diagnosis.     

A note on operator‐valued Fourier multipliers on Besov spaces

Let X be a Banach space. We show that each m : ? \ {0} → L (X ) satisfying the Mikhlin condition sup_{x ≠0}(‖m (x )‖ + ‖xm ′(x )‖) < ∞ defines a Fourier multiplier on B ^s _p,q (?; X ) if and only if 1 < p < ∞ and X is isomorphic to a Hilbert space; each bounded measurable function m : ? → L (X ) having a uniformly bounded variation on dyadic intervals defines a Fourier multiplier on B ^s _p,q (?; X ) if and only if 1 < p < ∞ and X is a UMD space. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Invertible linear maps preserving {1}-inverses of matrices over PID

Let R be a PID,chR = 2,n > 1, M_n(R) be then xn full matrix algebra over R.f denotes any invertible linear map preserving {1}-inverses from M_n(R) to itself. In this paper, we have proven thatf is an invertible linear map on M_n(R) preserving {1}-inverses if and only iff satisfies any one of the following two conditions: (i) there exists a matrixP ? GL _n(R) such thatf(A) =PAP ^?1 for allA ? M _n(R), (ii) there exists a matrixP ? GL _n(R) such thatf(A) =PA ^t P^?1 forA ? M _n(R).     

Nd:YAG纳米粉体的制备和光谱性质

采用共沉淀方法，以碳酸氢铵（NthHC03）为沉淀剂制备得到Nd：YAG前驱物，将其在不同的温度下煅烧并采用红外光谱（FT-IR）、X射线衍射（XRD）、透射电镜（TEM）、荧光光谱分析等技术对样品进行了表征。在900～1000℃下煅烧前驱物，出现YAP和YAM中间相并对共沉淀法中间相出现的原因进行了分析；获得纯YAG晶相的煅烧温度为1100℃，晶粒粒度分布约为40～80nm，具有良好的分散性。光谱研究表明Nd：YAG纳米粉体的发光性能良好，其红外光谱及荧光光谱与单晶无明显的差异。