煤结构模型研究及展望

从煤大分子结构模型、分子间结构模型和复合结构模型3个方面对煤的十几种典型结构模型进行了归类,对各模型的研究背景和研究方法进行了介绍和简要评述,并引入了我国学者新近发表的若干煤结构模型概念,指出其中的煤嵌布结构模型是目前煤化学界所提出的最为系统和全面的关于煤复合结构的概念描述,其研究过程反映了该嵌布结构模型是煤组成结构本质的一种自然体现,对煤溶解过程中的各种现象及煤的黏结性等可以作出合理的解释。

Effects of Solvent Molecules on the Interlayer Spacing of Graphene Oxide

Graphene oxide （GO） contains numerous functional groups that facilitate the intercalation of polar solvents. The properties and applications of GO are closely related to its interlayer spacing. We report on the changes in the interlayer spacing of GO after the adsorption of water molecules and the polar organic solvents C2H602 （EG）, C3HTNO （DMF）, C5H9NO （NMP）. Experiments were conducted to investigate the variations in the functional groups and structure of GO after solvent adsorp-tion, and they play a vital role in modeling and verifying the results of molecular dynamics simulation. The most stable GO structures are obtained through molecular dynamics simulation. The expansion of the interlayer spacing of GO after the adsorption of monolayer solvent molecules corresponds to the minimum three-dimensional size of the solvent molecules. The spatial arrangement of solvent molecules also contributes to the changes in interlayer spacing. Most adsorbed molecules are oriented parallel to the carbon plane of GO. However, as additional molecules are adsorbed into the interlaminations of GO, the adsorbed molecules are oriented perpendicular to the carbon plane of GO, and a large space forms between two GO interlayers. In addition, the role of large molecules in increasing interlayer spacing becomes more crucial than that of water molecules in the adsorption of binary solvent systems by GO.

STRUCTURE AND MORPHOLOGY CHANGES OF HYDROBIOTITES MODIFIED BY CATIONIC SURFACTANTS

In this study, X-ray diffraction （XRD）, Fourier transform infrared spectrometer （FTIR） together with Scanning probe microscopy （SPM） were used to characterize the structure and morphology of the complexes, where the hydrobiotites （Xinfiang） were modified by single-chain surfactants octyltrimethylammonium bromide （OTMA） and octadecyltrimethylammonium bromide （ODTMA）. XRD patterns showed that the structure of complexes was significantly influenced by the surfactant concentration and the alkyl chain length, because obvious changes took place in the basal spacing. Furthermore, according to the XRD results, several arrangements of surfactant molecules within the hydrobiotite interlayer space were deduced. The FTIR spectrum indicated that the surfactant contents in complexes dramatically increased with the alkyl chain length. The SPM micrographs demonstrated that the surfaces of complexes prepared at lower surfactant concentration were relatively flat compared with that prepared at higher concentration, while those with higher surfactant concentration had much steeper surface due to the alkyl chain length. It was concluded that structure and morphology of surfactant/hydrobiotite complexes depend not only on the surfactant concentration, but also strongly on the surfactant species.

Gelling Behavior of Plant Proteins and Polysaccharides in Food Systems

Biological macromolecules, such as proteins and polysaccharides, are widely used in food systems because their interactions impart a desirable texture to food products. Plant proteins interact with food components via protein-protein and protein-polysaccharide associations, and the formation of a matrix, which can entrap other food components such as water, lipids and flavors. These networks provide structural integrity to food products and can serve as important functional ingredients in processed foods. Intermolecular interactions of typical polysaccharides result either in simple associations or in the form of a double or triple helix. The linear double helical segments may then interact to form a super junction and a three-dimensional gel network. The formation of these structural networks takes place during processing and involves the transformation from a liquid or viscous sol into a solid material with elastic properties. Interests in the behavior of mixed gels center on the prospects of enhanced flexibility in their mechanical and structural properties compared to those of pure gels. Findings on molecular interactions between plant proteins （e.g., soy, canola and pea proteins） and polysaccharides （e.g., guar gum, carrageenan, and pectin） allow for the modification of physical and textural characteristics of mixed biopolymers to meet desired functional property.

Metal and Ligand Control on Structure and Functions of Ni（Fe）ARD： Role of Supramolecular Structures

Role of Ni（Fe）-macrostructures due to H-bonds in mechanisms of Ni（Fe）ARD action in methionine salvage pathway is discussed. The AFM method was used to research the possibility of the formation of stable supramolecular nanostructures based on Ni（Fe）ARD model systems {Ni（acac）2 ＋ L2 ＋ Tyr} （L2 = NMP （NMP = N-Methyl-2-pirrolidone）, His （His = L-Histidine）, Tyr （Tyr = L-Tyrosine）---with the assistance of intermolecular H-bonds. In the course of scanning of investigated samples, it has been found that the structures based on model systems are fixed on a surface strongly enough due to H-bonding. The self-assembly-driven growth of the supramolecular structures on modified Silicone surface based on researched complexes, due to H-bonds and perhaps the other non-covalent interactions was observed.

Manifestation If Substance Molecular Structure in Temperature Effects of Light Scattering

DCMSL （depolarization components of molecular scattering of light） have been studied within the wide spectral range （0-200 cm-1） and in the temperature intervals （20-200 ℃） in toluol （C6HsCH3） and aniline （C6HsNH2）. It has been shown that when a liquid is heated and temperatures approach to critical ones, a significant contribution of DCMSL is made by vibration motion of molecules. The special properties of the temperature-frequency behavior of DCMSL spectra are discussed from the view point of hindered rotation of liquid molecules with consideration of intermolecular interaction.

Theoretical Study on the Rotational Spectra of Ar-D232S Complex

We report a theoretical study on the rotational spectra of Ar-D232S. The intermolecular po- tential energy surface was transformed from our latest ab initio three-dimensional potential of Ar-H232S. The rotational energy levels and wavefunctions of the complex were calcu- lated by using the radial discrete variable representation/angular finite basis representation method and the Lanczos algorithm. The calculated rotational transition frequencies and structural parameters were found to be in good agreement with the available experimental values.

Synthesis and Crystal Structure of 2,2-Pentamethylene-1,2,3,4-tetrahydroquinazolin-4-one

The title compound 2,2-pentamethylene-1,2,3,4-tetrahydroquinazolin-4-one is of monoclinic, space group P21/n with a = 10.387(1), b = 10.954(2), c = 10.827(2) ? b = 110.77(1), C13H16N2O, Mr = 216.28, Z = 4, V = 1151.8(4) 3, Dc = 1.247 g/cm3, m(MoKa) = 0.080 mm-1, F(000) = 464, R = 0.0499 and wR = 0.1217 for 1575 observed reflections (I > 2s(I)). X-ray analysis reveals that the pyrimidine and cyclohexane rings adopt half-chair and chair configurations, respectively. In addition, there exists an intermolecular hydrogen bond (N(1)H(1)…O) in the product molecule.

Controlling the solid-state luminescence of gold(I) N-heterocyclic carbene complexes through changes in the structure of molecular aggregates

Thermally stable, solid-state luminescent organic materials are highly desired for the development of practical applications.Herein we synthesized new gold(I) complexes with N-heterocyclic carbene ligands, which have the ability to form strong metalorganic bond. Consequently, their thermochemical stability is enhanced at temperatures around 300 °C. Precise design of the molecular structure of the ligands, with a focus on ensuring low steric hindrance around Au atoms in order to limit disturbances to Au/Au interactions, provided a complex with a densely packed crystal with a shorter intermolecular Au–Au distance(3.17 ?)than the typical distance. In the solid state, this complex exhibited strong aurophilic interactions, which generated intense phosphorescence even in air at room temperature(quantum yield=16%) in spite of absence of any phosphorescence in solution.This behavior is characteristic for solid-state luminescence referred to as aggregation-controlled emission. Furthermore, the gold(I) complex displays capacity for mechano-and vapo-chromism—that is, the ability to change color reversibly in response to the application of external stimuli. We believe that the proposed design framework, which involves controlling thermal stability and luminescence property separately, provides a new opportunity for the development of practical applications using solid-state luminescent organic molecules.

Prevalent intrinsic emission from nonaromatic amino acids and poly(amino acids)

Nonaromatic amino acids are generally believed to be nonemissive, owing to their lack of apparently remarkable conjugation within individual molecules. Here we report the intrinsic visible emission of nonaromatic amino acids and poly(amino acids) in concentrated solutions and solid powders. This unique and widespread luminescent characteristic can be well rationalized by the clustering-triggered emission(CTE) mechanism, namely the clustering of nonconventional chromophores(i.e. amino, carbonyl,and hydroxyl) and subsequent electron cloud overlap with simultaneous conformation rigidification. Such CTE mechanism is further supported by the single crystal structure analysis, from which 3 D through space electronic communications are uncovered.Besides prompt fluorescence, room temperature phosphorescence(RTP) is also detected from the solids. Moreover, persistent RTP is observed in the powders of exampled poly(amino acids) of ε-poly-L-lysine(.-PLL) after ceasing UV irradiation. These results not only illustrate the feasibility of employing the building blocks of nonaromatic amino acids in the exploration of new luminescent biomolecules, but also provide significant implications for the emissions of peptides and proteins at aggregated or crystalline states. Meanwhile, they may also shed lights on further understanding of autofluorescence from biological systems.

Recent advances of intermolecular Diels–Alder reaction in bio-inspired synthesis of natural products

The Diels–Alder(D–A)reaction is one of the most powerful reactions in organic synthesis.The intermolecular D–A reaction attracts much less attentions than its intramolecular counterpart in natural product synthesis,possibly due to the issues of reactivity and selectivity.In the past decade,the intermolecular D–A reaction has been increasingly utilized in the total synthesis of structurally complex natural products.In this article,we present a few examples for the elegant applications of the intermolecular D–A reaction that are inspired by biosynthetic hypotheses of the target natural products.These examples demonstrate that D–A reaction is not only useful for preparing building blocks but also powerful for coupling structurally complicated and sterically demanding segments in a highly chemo-and stereo-controlled fashion,which may inspire further developments of intermolecular D–A reaction from both strategy and methodology perspectives.

Fluctuation limits of strongly degenerate branching systems

Functional limit theorems for scaled occupation time fluctuations of a sequence of generalized branching particle systems in Rd with anisotropic space motions and strongly degenerated splitting abilities are studied in the cases of critical and intermediate dimensions. The results show that the limit processes are time-independent measure-valued Wiener processes with simple spatial structure.