Polarized Raman Spectra VI. A Short Note on the Raman Spectra of p-Polyphenyls

The Raman spectra of the p-polyphenyls: benzene, biphenyl, p-terphenyl, and p-quaterphenyl, are compared with their electronic spectra. The relative intensity of the double bond stretching mode around 1600 Kaisers to that of the breathing mode around 1000K increases steadily when the phenyl chain is lengthened. This intensity ratio can be calculated using our theory proposed previously.¹ The results are in very good agreement with the experimental observations     

Polarized Raman Spectra VII Correlations and Assignments of Raman Lines in p-Polyphenyls

The Raman spectra of powdered biphenyl, p-terphenyl, and p-quaterphenyl are compared with each other and also with the Raman spectrum of benzene. Most Raman lines in polyphenyls can be considered as derived from normal vibrations in benzene. The intense lines are thus assigned and the correlations between them are established.     

基于定向纳米碳管气体放电的气敏传感器研究

介绍了一种基于定向纳米碳管的气敏传感器,以生长定向纳米碳管的氧化铝模板作为阳极,铝板作为阴极,利用纳米碳管的尖端发射效应,在较低的电压下使气体产生放电现象。通过对纳米碳管在气体中击穿电压和放电电流的测量,实现对气体的定性定量检测。同时纳米碳管气敏传感器还具有体积小、灵敏度高、稳定性好、响应速度快、在常温常压下即可进行检测等优点,具有较好的应用前景。     

Hydrogen bonding and π–π stacking in 6‐hydroxy­biochanin A monohydrate

In the lattice of the title compound (systematic name: 5,6,7‐trihydroxy‐4′‐meth­oxy­isoflavone monohydrate), C₁₆H₁₂O₆·H₂O, the isoflavone mol­ecules are linked into chains through R₄³(17) motifs composed via O—H⋯O and C—H⋯O hydrogen bonds. Centrosymmetric R₄²(14) motifs assemble the chains into sheets. Hydrogen‐bonding and aromatic π–π stacking inter­actions lead to the formation of a three‐dimensional network structure.     

A mechanistic and synthetic study of organocopper substitution reactions with some homoallylic and cyclopropylcarbinyl substrates : Application to isoprenoid synthesis

The double bond of cholesteryl and 5-norbornen-2-yl tosylates and the cyclopropane ring of cyclopropylmethylcarbinyl tosylate participate in organocuprate substitution reactions; retention of configuration at the nucleofugal sp³-C atom and skeletal reorganizations are observed. A plausible mechanism for these reactions is discussed. Coupling of homogeranyl iodide with a four-carbon, functionalized, vinylic cuprate reagent is applied to stereospecific synthesis of trans, trans-farnesol.     

One-pot Synthesis of Isoxazolines Using Soluble Polymer-supported Acrylate

An eficient liquid-phase synthesis of isoxazolines through a 1,3-dipolar cycloaddition is described.Soluble polymer-supported acrylate reacted with nitrile oxides generated in-situ,followed by cleavage from the support giving corresponding isoxazolines in high yields and excellent purities.     

Theoretical Study of the C_(60)O_3 Isomers

WiththepreparationandisolationofC,,O.'moreandmoreattentionwaspaidtotheirstructuresandpropertiest').WooddetectedC,,O.firstwhentheypreparedC,,byvaporizinggraphite").Fromthenon,thelaboratoriesallovertheworldhavepreparedC6,O.byvariousmethodssuchasPhotoxidationt2-4),Electrochemicaloxi-dation[si,Ozonizationt7.83andChemicaladditiont6'12-14iandsoon.Accordingtothefollow-uptheoreticalstudiesforC,,O.,itisindicatedthattherearetwoisomersofC,,O:eithertheoxygenatomislocatedoverthe6/6bondtogeneratethe6/…     

Development and validation of HPLC methods for enantioseparation of mirtazapine enantiomers at analytical and semipreparative scale using polysaccharide chiral stationary phases

Novel HPLC methods were developed for the analytical and semipreparative resolution of new antidepressant drug mirtazapine enantiomers. At analytical scale, the separation of the mirtazapine enantiomers was investigated using both cellulose and amylose tris(3,5-dimethylphenylcarbamate) (CDMPC and ADMPC) chiral stationary phases under normal-phases and polar organic modes. Good baseline enantioseparation was achieved using cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phases under both normal-phases and polar organic modes. Furthermore, the elution order of mirtazapine enantiomic pairs was found reversed by changing the stationary phase from the amylose-based ADMPC–CSPs to its cellulose-based counterpart, CDMPC–CSPs. The validation of the analytical methods including linearity, limit of detection (LOD), limit of quantification (LOQ), recovery and precision, together with the semipreparative resolution of mirtazapine racemate were carried out using cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phases and methanol as mobile phase without any basic additives under polar organic mode. At analytical scale, the elution times of both enantiomers were less than 6 min at normal temperature and 1.0 ml/min, with the separation factor () 1.99 and the resolution factor (Rs) 3.56. Then, the analytical methods were scaled up to semipreparative loading to obtain small quantities of both mirtazapine enantiomers. At semipreparative scale, about 16 mg/h enantiomers could be isolated and elution times of both enantiomers were less than 10 min at 2.0 ml/min. To increase the throughput, the technique of boxcar injections was used. One enantiomer ((−)-(R)-mirtazapine) was isolated with purity of >99.9% e.e. and >98.0% yield and another ((+)-(S)-mirtazapine) was isolated with purity of >97.0% e.e. and >99.0% yield. In addition, optical rotation and circular dichroism (CD) spectroscopy of both mirtazapine enantiomers isolated were also investigated.     

Self－assembly of Novel Hetero[3]rotaxane, [2]Rotaxanes and [2]Catenane

One linear template 13 and one cyclophane template 15, both incorporating two electron rich 1,4‐dialkoxybenzene units and one diamide unit, have been synthesized. By utilizing donor‐acceptor interaction and/or intermolecular hydrogen bonding assembling principles, one novel hetero[3]rotazane 22·4Cl, possessing one neutral and one tetracationic ring components, has been synthesized from 13, through neutral [2]rotaxane 21 as intermediate. With 15 as template, tetracationic [2]catenane 23·4PF₆ was assembled by using donor‐acceptor interaction, but no neutral [2]rotaxane could be obtained under the typical conditions of hydrogen bonding assembling principle. The interlocked supramolecular compounds have been characterized and their spectral properties are investigated.     

Microwave assisted hydrothermal synthesis of tin niobates nanosheets with high cycle stability as lithium-ion battery anodes

SnNb₂O₆ and Sn₂Nb₂O₇ nanosheets were synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. Compared with Sn₂Nb₂O₇ and the previously reported pure Sn-based anode materials, the SnNb₂O₆ electrode exhibited outstanding cycling performance.