β-榄香烯振动光谱的量子化学从头计算

利用G98及GAMESS从头计算程序的RHF／6－31方法,对β－榄香烯的全部振动基频作了计算,并与实测红外光谱做了对比,归属了它们的振动模式,讨论了它们的特征基频,并对理论计算的振动频率进行了标度校正。     

Editorial

Mobile pedestrian navigation systems are one of the most popular Location-Based Services. In the era of Web 2.0, current mobile navigation systems often suffer from the following problems: the lack of social navigation support (utilising other people's experiences) and the challenge of making user-generated content (UGC) useful. In this article, some collective intelligence-based route recommendation methods are designed to address these problems. The proposed methods can make use of UGC (reflecting other users’ navigation experiences), and provide users with the least complex and the length-complexity-optimised (LCO) routes. Some simulations using the street network of the first district of Vienna (Austria) are designed to evaluate the proposed methods. The results show that compared to the shortest route, the collective intelligence-based routes (i.e. the least complex and the LCO routes) have a significant improvement of the route quality (with lower complexity ratings), thereby more effectively supporting users’ navigation tasks (more chances of reaching the destination, fewer mistakes made and shorter distance travelled).     

A 2D Co(II) coordination polymer based on 1,3,5-tris(1H-imidazol-1-yl)benzene: photocatalytic properties and theoretical analysis

Abstract

A new 2D Co(II) based coordination polymer (CP), {[Co₂(tib)₂(NO₃)₃(H₂O)₂·NO₃]_n (1), has been synthesized using 1,3,5-tris(1-imidazolyl)benzene (tib) ligand. The single crystal X-ray diffraction study indicates that 1 possesses an infinite 2D layer, which is further extended into a 3D supramolecular network via O–H···O hydrogen bonding interactions. Additionally, the thermogravimetric analysis (TGA) of CP indicates its decomposition temperature was about 268?°C. The UV/Vis diffuse-reflection spectrum of 1 indicates its semiconducting nature on the basis of which the photocatalytic properties of 1 against photodecomposition of organic dyes have been studied. The possible mechanism associated with the photocatalytic activity of 1 against organic dyes is addressed using density of states (DOS) calculations.     

Coumarinyl azoimidazolyl complexes of osmium(II) hydridocarbonyls: spectroscopic and structural characterization,oxidation catalysis,photovoltaic effect and density functional theory computation

Os(II) hydridocarbonyl complexes of coumarinyl azoimidazoles, [Osh(CO)(PPh₃)₂(CZ‐4R‐R′)]^0/+ ( 3 , 4 ) (CZ‐R‐H = 2‐(coumarinyl‐6‐azo)‐4‐substituted imidazole or 1‐alkyl‐2‐(coumarinyl‐6‐azo)‐4‐substituted imidazole), were characterized from spectroscopic data and the single‐crystal X‐ray data for one of the complexes, [Osh(CO)(PPh₃)₂(CZ‐4‐Ph)] ( 3c ) (CZ‐4‐Ph = 2‐(coumarinyl‐6‐azo)‐4‐phenylimidazolate), confirmed the structure. The complexes show higher emission (quantum yield ? = 0.0163–0.16) and longer lifetime (τ = 1.4–10.3 ns) than free ligands (? = 0.0012–0.0185 and τ = 0.685–1.306 ns). Cyclic voltammetry shows quasi‐reversible metal oxidation at 0.67–0.94 V for [Os(III)/Os(II)] and 1.21–1.36 V for [Os(IV)/Os(III)] and subsequent azo reductions (?0.68 to ?0.95 V for [? N?N? ]/[? N N? ]^? and irreversible < ?1.2 V for [? N N? ]^?/[? N? N? ]^2?) of the chelated coumarinyl azoimidazole. The complexes are photostable and show better photovoltaic power conversion efficiency than free ligands. Also, the complexes were used as catalysts for the oxidation of primary/secondary alcohols to aldehydes/ketones using oxidizing agents like N‐methylmorpholine N‐oxide, t‐BuOOH and H₂O₂. Density functional theory computation was carried out from the optimized structures and the data obtained were used to interpret the electronic and photovoltaic properties. Copyright © 2016 John Wiley & Sons, Ltd.     

Computation and conversion of brain pH values obtained with two algorithms of phosphorus magnetic resonance spectroscopy data analysis

The intracellular brain pH in phosphorus magnetic resonance spectroscopy is calculated using the chemical shift between the inorganic phosphate and phosphocreatine with the Henderson–Hasselbalch equations. Researchers use various mathematical formulas that have different parameters and get various results for the same input data as a consequence. Thus, the aim of this article was to determine the mathematical formulas that allow the conversion of the pH values obtained by the most popular analysis methods to each other. To determine the relationships between pH results and the applied mathematical formula, the pH values were calculated using two algorithms for the theoretical chemical shift values. The pH results were compared with each other using the appropriate t-tests. Mathematical formulas were designed to simplify the conversion of pH values obtained by two data analysis methods to each other. The pH values with were obtained this way did not differ significantly from the pH values calculated directly from the given formula. The computed mathematical formulas will make it possible to simplify pH conversions without knowing the chemical shift between inorganic phosphate and phosphocreatine but only basing on the final pH values obtained by one of the formulas.     

Lewis acid-base adducts of zwitterionic alkali metal methanides and silanides with BH3

The synthesis, structures and spectroscopic properties of M(MeOCH₂CH₂OMe₂Si)₃CBH₃ (M-1-BH₃) and M(MeOCH₂CH₂OMe₂Si)₃SiBH₃ (M-2-BH₃) (M?=?Li, Na, K) derived from reactions of BH₃ with the alkali metal zwitterions [M(MeOCH₂CH₂OMe₂Si)₃C] (M-1) and [M(MeOCH₂CH₂OMe₂Si)₃Si] (M-2) (M?=?Li, Na, K), resp., are reported. X-ray analysis and DFT calculations reveal discrete zwitterionic structures with the octahedral alkali metal cations rigidly locked and charge separated from the BH₃ units via pendant donors groups. Solution experiments with the hydride acceptors B(C₆F₅)₃ and [Ph₃C]₂[B₁₂C₁₂] indicate that Na-1-BH₃ can donate hydrides to form cations of formula [Na(MeOCH₂CH₂OMe₂Si)₃CBH₂]⁺.     

柚皮素/β-环糊精超分子体系的包合行为

本文采用超声法制备了柚皮素（NAR）与β-环糊精（βCD）的包合物.粉末-X射线衍射（XRD）和红外吸收光谱（IR）测定均表明形成的包合物具有不同于主客体的新的结构性质.¹H NMR与ROESY核磁共振（NMR）实验表明NAR以苯环端从βCD的宽口端进入，并形成稳定的超分子包合物.量子化学计算分析NAR/βCD包合物的形成过程表明，驱动力源于焓驱动与氢键弱相互作用力；能隙和结合能分析得到的最优包合模式与NMR研究结果一致；ONIOM分层计算验证了上述结果.分子对接模拟出的最优包合模式也与量子化学计算、NMR的分析结果吻合.本文获取了清晰的NAR/βCD包合物构型及其形成机理，为该超分子药物的定量构效关系研究提供了理论参考.     

Anomalous electronic transport in quasicrystals and related complex metallic alloys

We analyse the transport properties in approximants of quasicrystals α-AlMnSi, 1/1-AlCuFe and for the complex metallic phase λ-AlMn. These phases present strong analogies in their local atomic structures and are related to existing quasicrystalline phases. Experimentally, they present unusual transport properties with low conductivities and a mix of metallic-like and insulating-like characteristics. We compute the band structure and the quantum diffusion in the perfect structure without disorder and introduce simple approximations that allow us to treat the effect of disorder. Our results demonstrate that the standard Bloch–Boltzmann theory is not applicable to these intermetallic phases. Indeed their dispersion relations are flat, indicating small band velocities, and corrections to quantum diffusion, which are not taken into account in the semi-classical Bloch–Boltzmann scheme, become dominant. We call this regime the small velocity regime. A simple relaxation time approximation to treat the effect of disorder allows us to reproduce the main experimental facts on conductivity qualitatively and even quantitatively.     

Crystal structure and DFT calculations of methanol {E-N′-(2-hydroxybenzlidene)benzohydrazido}dioxidomolybdenum (VI) complex

The crystal and molecular structure of methanol {E-N′-(2-hydroxybenzlidene)benzohydrazido}dioxidomolybdenum (VI) was determined by single crystal X-ray diffraction. B3LYP/DZP basis set theoretical calculations nicely reproduce the X-ray experimental geometry. The obtained results are discussed in connection with the electronic and structural properties of the compound.     

Formation and dissociation of protonated cytosine–cytosine base pairs in i-motifs by ab initio quantum chemical calculations

Formation and dissociation mechanisms of C-C＋ base pairs in acidic and alkaline environments are investigated, employing ab initio quantum chemical calculations. Our calculations suggest that, in an acidic environment, a cytosine monomer is first protonated and then dimerized with an unprotonated cytosine monomer to form a C-C＋ base pair; in an alkaline environment, a protonated cytosine dimer is first unprotonated and then dissociated into two cytosine monomers. In addition, the force for detaching a C-C＋ base pair was found to be inversely proportional to the distance between the two cytosine monomers. These results provide a microscopic mechanism to qualitatively explain the experimentally observed reversible formation and dissociation of i-motifs.