2-(1或2萘基)苯并噁唑的电子结构与光物理性质

本文用PPP-SCF-CI法对2-(1或2萘基)苯并噁唑及其Z、E同分异构体的电子结构及紫外光谱进行了理论研究,讨论了各分子的光谱特性,解析了对应于实验的不同异构体紫外吸收光谱,找到了该分子体系的主要生色团,理论计算与实验结果的偏差约在1%以内。这为深入研究苯并噁唑类分子的光物理性质、进一步预测具有更好性能的新型材料提供了理论依据。     

氮杂双环型化合物结构的NMR研究

该文基于2-苯基-2-环戊基-2-羟基乙酸-3-甲基-3-氮杂双环(3,3,1)壬-9?-酯,对氮杂双环型化合物的立体化学结构的NMR测定方法进行了研究.结果表明,采用选择性远程DEPT与多频率位移选择激发一维(1D)NOESY相结合的方法,可有效解决该类化合物NMR谱的碳信号归属困难的问题,同时有助于构型和立体结构的测定.该方法对于准确阐明氮杂双环型化合物的化学结构和立体化学特征具有较好的指导意义.     

镧系离子与L—组氨酸配合物^13CNMR波谱及其结构的研究

本文以XL-200型超导NMR谱仪对镧系离子与L-组氨酸配合物进行了一系列的研究,测得微酸性条件下的顺磁诱导位移,对这些诱导位移进行分析计算,得到了各磁性核的配合物生成位移、接触位移和准接触位移,同时以准接触位移为依据,对配合物结构进行模拟,获得了有关的结构参数.并对镧系离子在磁学性质上的特征进行了讨论.     

层状结构化合物研究的进展

近年来,层状化合物的研究日益受到重视。本文从介绍层状化合物的晶体结构出发,讨论层状化合物的电子结构和物理性质的研究进展,侧重于石墨插层化合物和过渡金属二硫属元素化合物。对电荷密度波也作了简单的介绍。     

Investigations on ternary B-C-N materials

Isoelectronic BC _x N compounds have been researched widely. However, electron-deficient boron-rich B-C-N solids have also attracted much interest both theoretically and experimentally. In this paper, we introduce the synthesis, theoretical prediction, and physical properties of crystalline ternary B-C-N compounds. Our recent work reveals that the novel B-C-N materials may have a wide variety of crystal structures with different characteristics.      

Mössbauer spectroscopic studies of MIIMIVS3 (MII=Sn,Pb; MIV=Sn,Ge, Hf) and PbSnS2Se

Temperature-dependent Mössbauer experiments have been carried out to examine the lattice dynamical properties of tin sites in Sn₂S₃ and its related compounds. The differences in the lattice parameters, estimated from the temperature dependence of the area intensities for the compounds, are attributed to the characteristics of their crystal structures.     

The investigation of the photonic waveguide structure made of silicon carbide by means of the method of the singular integral equations

Here we present the analyses of the open (without a metal screen) ridged and photonic waveguide structures by means of the electrodynamical rigorous method of the Singular Integral Equations (SIE). The waveguides are made of a lossy silicon carbide (SiC) material. We have discovered peculiarities of the dispersion characteristics. We have found the numerical solutions to the complex wave equations. The dispersion characteristics of both waveguide structures are numerically analyzed and compared with each other. It was found that the losses of modes propagating in the waveguide structure with air openings (channels) are smaller than the losses in the waveguide structure without air openings. We came to the conclusion that it is possible to optimize the dispersion characteristics by adding openings of different shapes and sizes into the waveguide structures.     

The electronic properties of SiCAlN quaternary compounds

We have investigated the properties of SiCAlN quaternary compounds composed of SiC and AlN polytypes by first-principle calculations. We find that their band gaps have a large tunability and are sensitive to the polytype structures. Their electronic properties vary from wide-band-gap semiconducting to metallic due to the complex charge transfer between the two constituents SiC and AlN. The formation energies are also calculated. These results show SiCAlN quaternary compounds have potential applications in the electronic devices that can be tuned over a large wavelength range.     

Spectral, luminescent, photochemical, and laser properties of a series of boron fluoride complexes of dipyrrolylmethenes in solutions

We have studied the spectroscopic and lasing characteristics of active media based on two synthesized boron fluoride complexes of alkyl-substituted dipyrrolylmethenes and the photostability of the complexes in comparison with complexes of this kind that were previously studied in the literature under identical excitation conditions. We have determined and analyzed conditions under which new compounds have either merits or drawbacks as compared to the known dye with respect to both lasing efficiency and resource characteristics.     

Magnetism of actinide compounds

We review the physical properties of actinide compounds, with particular emphasis on their magnetic characteristics. Because of the complexity of these materials, mainly the simplest compounds are treated, some of which have properties that can be theoretically explained.     

Structural, electronic and phonon properties’ investigation of YP and YAs compounds

We have studied the structural, electronic and phonon properties of the YP and YAs compounds in NaCl(B1) and CsCl(B2) structures using the density functional theory within the generalized gradient approximation (GGA). The calculated lattice constants, static bulk modulus, first-order pressure derivative of the bulk modulus and transition pressure are reported and compared with previous calculations. We have carried out the calculations of band structure and density of states (DOS) for YP and YAs. Then, a linear-response approach to the density-functional theory is used to derive the phonon frequencies and DOS in both B1 and B2 structures.     

Stability,elasticity and electronic structures of Co-Zr binary intermetallic compounds

ABSTRACT

The structural properties, enthalpies of formation and entropic temperatures of five stable Co-Zr intermetallics were systematically investigated by first-principles calculations. The calculated enthalpy of formation was used to measure the phase stability of the Co-Zr intermetallic compounds, and the results reveal that CoZr has the highest phase stability among these Co-Zr compounds. Considering the change of temperature, the entropic temperature T_S was used to illustrate the high-temperature stability of the Co-Zr intermetallic compounds. Additionally, the elastic constants, anisotropy indexes and Debye temperatures have been calculated. According to the calculated anisotropy indexes, CoZr₂ has the highest elastic anisotropy among the Co-Zr binary compounds. Furthermore, the bonding characteristics of these compounds have also been investigated by calculating the electronic structures.     

Photoprocesses in complex organic compounds

We present the results of investigations of photoprocesses in organic compounds. We have done a theoretical and experimental study of the relationship of photophysical and photochemical processes in organic molecules to the characteristics features of intramolecular and intermolecular interactions and the exciting electromagnetic field. We have developed quantum chemical procedures for theoretical prediction of the structure of organic compounds with specified physicochemical and optical properties. We have designed new active media for lasers with enhanced photostability and increased lifetime. Translated from Izvestiya Vysshkh Uchebnykh Zavedenii, Fizika, No. 8, pp. 76–86, August, 1998.     

Electronic and conformational properties of 2,3-benzodiazepine derivatives

Summary The molecular geometries and electronic structures of 2,3-benzodiazepine derivatives have been studied by means of the MNDO-PM3 method. A number of electronic properties have been computed and examined in order to find indication of the role of the electronic characteristics of the different molecules and their pharmacological properties. Theoretical data indicate that both electronic and structural properties appear responsible for the varying degree of anticonvulsant activity exhibited by compounds 1–4.     

Study on mechanical behavior and electronic structures of Al-Cu intermetallic compounds based on first-principles calculations

In this paper, we use first-principles calculations to study the correlation between mechanical behaviors and electronic structures of Al-Cu intermetallic compounds. We find that in general, the ductility of intermetallic compounds decreases with the increase in Cu content, while the corresponding work function increases but densities of states decrease. Moreover, homogeneous and symmetrical or small anisotropic charge distributions correspond to small brittleness. The present study therefore suggests that the primary origin of brittleness in intermetallic compounds can be well related to their electronic structures.     

美登木属植物中木栓烷型三萜的结构及其~(13)C NMR波谱特征

卫矛科美登木属(Maytenus)植物因发现具有较强抗肿瘤活性而备受关注,其中木栓烷型三萜是主要活性成分之一,并具有较特征的A环或A/B环均为芳香化结构.该文综述了近年(1995~2013年)来美登木属植物中木栓烷型三萜的结构类型及其13C NMR特征,为这类化合物的结构鉴定和波谱数据归属提供参考.     

Theoretical study of the phosphorescence of 8-azasteroids

We have used quantum chemical methods for a theoretical study of the luminescent characteristics (including estimating the rate constants for intramolecular T₁ → S₀ electronic transitions) of the molecules of four immunoactive compounds of the 8-azasteroid class. We have established that the T₁ state is localized on the enaminodicarbonyl moiety that is common to all the molecules. We have shown that for the studied compounds, the phosphorescence spectra and the physical mechanisms for deactivation of the lower triplet state T₁ are similar. For all the compounds, the results of the theoretical study are consistent with the corresponding conclusions of experimental studies of 8-azasteroids. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 751–755, November–December, 2006.     

Current-induced nonequilibrium spin polarization in semiconductor-nanowire/s-wave superconductor junctions with strong spin–orbit coupling

We have studied the characteristics of current-induced nonequilibrium spin polarization in semiconductor-nanowire/swave superconductor junctions with strong spin–orbit coupling. It was found that within some parameter regions the magnitude of the current-induced nonequilibrium spin polarization density in such structures will increase(or decrease) with the decrease(or increase) of the charge current density, in contrast to that found in normal spin–orbit coupled semiconductor structures. It was also found that the unusual characteristics of the current-induced nonequilibrium spin polarization in such structures can be well explained by the effect of the Andreev reflection.     

Structures and physical properties of R_2TX_3 compounds

Rare-earth compounds have been an attractive subject based on the unique electronic structures of the rare-earth elements. Novel ternary intermetallic compounds R2TX3 (R = rare-earth element or U, T = transition-metal element, X = Si, Ge, Ga, In) are a significant branch of this research field due to their complex and intriguing physical properties, such as magnetic order at low temperature, spin-glass behavior, Kondo effect, heavy fermion behavior, and so on. The unique physical properties of R2TX3 compounds are related to distinctive electronic structures, crystal structures, micro-interaction, and external environment. Most R2TX3 compounds crystallize in AlB2-type or derived AlB2-type structures and exhibit many similar properties. This paper gives a concise review of the structures and physical properties of these compounds. Spin glass, magnetic susceptibility, resistivity, and specific heat of R2TX3 compounds are discussed.     

Fluorescence Study of Imidazoquinoxalines

The fluorescence properties of eleven novel derivatives based on the imidazo[1,2-a]quinoxaline structures have been studied. The absorption and emission spectra of these compounds have been recorded in dimethylsulfoxide solution. The phenyl substituting group on position 1 gives them particular properties thanks to the diverse hydroxy or methoxy decorating moieties, especially when they are multiplied or mixed. The investigated fluorescence auto-quenching revealed that the decreasing fluorescence intensity correlated only with the chemical structures of the aromatic compounds.