Global minimum geometries of acetylene clusters (HCCH)n with n ≤ 55 obtained by a heuristic method combined with geometrical perturbations

Geometry optimization of acetylene clusters (HCCH)_n in the range of n ≤ 55 was carried out with a recently proposed intermolecular potential consisting of Morse potentials, damped dispersion terms, and damped Coulomb terms. The heuristic method developed by the present author was used in the optimization: optimal geometries were searched by using geometry perturbations and subsequent local optimizations. The calculations were repeated until the global minimum was found for each cluster at least three times. The obtained results were analyzed to examine structural evolution of the clusters. The geometries of the clusters with n ≥ 25 were similar to the geometry in the cubic crystal of acetylene whereas smaller clusters take icosahedron‐based geometries. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010     

Experimental and theoretical study of N2-broadened acetylene line parameters in the ν1 + ν3 band over a range of temperatures

N₂-broadened line widths and N₂-pressure induced line shifts have been measured for transitions in the ν₁?+?ν₃ band of acetylene at seven temperatures in the range 213–333?K to obtain the temperature dependences of broadening and shift coefficients. For the room-temperature spectra the line mixing effects have been also investigated. The Voigt and hard-collision line profile models were used to retrieve the line parameters. All spectra were recorded using a 3-channel tuneable diode laser spectrometer. The line-broadening and line-shifting coefficients as well as their temperature-dependence parameters have been also evaluated theoretically, in the frame of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole–quadrupole and pairwise atom–atom interactions as well as on exact trajectories driven by an effective isotropic potential.     

几种非晶态Ni-B合金催化剂的物化和催化性能比较

用化学还原法制备非晶态Ni—B合金和浸渍-化学还原法制备非晶态Ni—B／Al2O3、Ni—B／SiO2、Ni—B／CNTs合金,研究丁催化剂的己炔选择加氧性能,并运用TEM、ICP、XPS、H2-TPD、CO化学吸附法对非晶态合金催化剂进行表征。结果表明,Al2O3、SiO2、CNTs载体不同程度促进了Ni—B合金的分散,提高了催化剂的活性镍表面积,其中以CNTs的效果最为突出。平均径粒为10nm左右的Ni—B粒予在CNTs表面均匀分散,使活性镍的表面积达30.6m^2／g,提高了氰的吸附量。此外,CNTs向非晶态Ni—B合金中的Ni转移电子,形成富电子的Ni。Ni—B／CNTs催化剂具有最好的乙炔加氢活性,Ni—B催化剂乙烯选择性最差。     

用乙炔稳频二极管-泵浦Er-Yb玻璃激光器

介绍了一种新颖的二极管-泵浦Er-Yb玻璃激光器,利用Pound-Drever-Hall技术并采用乙炔分子P（15）线对其实现了稳频。实验装置中将两个激光器的出射波长锁定到同一气室的乙炔P（15）吸收曲线的同一侧,使得温度对吸收峰值频率产生的漂移和温度导致气压变化使线宽增宽均对频率稳定性不产生影响。通过测量两个相同激光器系统间出射光波的拍频发现,激光的短期带宽窄于50kHZ,通过频率波动情况得出激光器有较高的相对频率稳定度。改进后的激光器稳定性和重复性显著提高,适合于实现高精度的光学频率标准。     

Molecular Mechanisms behind Acetylene Adsorption and Selectivity in Functional Porous Materials

Since its first industrial production in 1890s, acetylene has played a vital role in manufacturing a wide spectrum of materials. Although current methods and infrastructures for various segments of acetylene industries are well-established, with emerging functional porous materials that enabled desired selectivity toward target molecules, it is of timely interest to develop new efficient technologies to promote safer acetylene processes with a higher energy efficiency and lower carbon footprint. In this Minireview, we, from the perspective of materials chemistry, review state-of-the-art examples of advanced porous materials, namely metal–organic frameworks and decorated zeolites, that have been applied to the purification and storage of acetylene. We also discuss the challenges on the roadmap of translational research in the development of new solid sorbent-based separation technologies and highlight areas which require future research efforts.     

Carpet Beater Molecules: Synthesis and Characterization of Functional Hexa-peri-benzocoronene–Alkyne Coupling Products

Within the scope of this paper, nine π-expanded mono-substituted 5,8,11,14,17-pentakis-(tert-butyl)-hexa-peri-hexabenzocoronenes (HBC) are introduced. 2-Iodo-5,8,11,14,17-pentakis-(tert-butyl)-hexa-peri-hexabenzocoronene served as precursor and was reacted with ethynyltrimethylsilane in a Sonogashira coupling reaction. The acetylene unit is used as a linker and can undergo another Sonogashira coupling reaction combining different phenyl coupling partners with the HBC core. The electron-withdrawing groups such as nitrile, pyridine and carbonyl species (aldehyde, methylester, carboxylic acid) as well as the three quinoxaline based species (diphenylquinoxaline, dibenzo[a,c]phenazine, phenanthro[4’,5’-a,b,c]phenazine) serve as substitution moieties. Their influence on the optoelectronic properties were investigated by UV/Vis absorption spectroscopy demonstrating a maximum redshift of 7 nm compared to starting compound 2-Iodo-5,8,11,14,17-pentakis-(tert-butyl) HBC. As for the phenanthro[4’,5’-a,b,c]phenazine substituted HBC a dramatic decrease in the intensity of the absorption of the UV/Vis spectrum was observed. The fluorescence spectroscopy pointed out that the dibenzo[a,c]phenazine and phenanthro[4’,5’-a,b,c]phenazine substitution changed the spectra to one broad peak departing from the characteristic HBC-like emission pattern.     

Design and Application of Amphiphilic Polymeric Supports for Micellar Catalysis

In this contribution, the synthesis and application of amphiphilic poly(2-oxazoline)s with covalently bound transition metal catalysts for reactions in aqueous media is described. In the first example, bipyridine moieties were introduced via living ring-opening polymerization of functionalized oxazoline monomers and the resulting block copolymers were used as macroligands for ATRP (atom transfer radical polymerization) using Cu(I)Br as active metal species. Furthermore, the fixation of a chiral biphosphane and its use for enantioselective hydrogenation of enamides is presented as well as the fixation of a ruthenium catalyst. The latter one is used for polymerization of diethyl dipropargylmalonate (DEDPM), and represents the first example of an alkyne polymerization using a ruthenium catalyst. In the case of the polymers stable latex particles were obtained     

一个微孔钴基金属有机骨架的合成及其选择性气体吸附

利用硝酸钴与配体5，5''-di (1H-1，2，4-triazol-1-yl)-(1，1''-biphenyl)-2，2''-dicarboxylic acid (H₂DTBDA)进行溶剂热反应，制备了一个结构新颖的金属有机骨架{[Co (DTBDA)]₂·DMF·MeOH}_n (FJI-H37)。FJI-H37不仅具有适合气体分子吸附的0.69 nm的微孔，还具有良好的热稳定性及有机溶剂容忍性。气体吸附测试表明FJI-H37不仅能从C₂H₂/CO₂(体积比50∶50)混合气中选择性吸附C₂H₂，还可以从CO₂/N₂(体积比15∶85)和CO₂/CH₄(体积比50∶50)混合气中选择性捕获CO₂；固定床突破实验进一步证实了其高效的气体分离能力。