摘要:

AbstractFor heat energy storage application, polyurea microcapsules containing phase change material,n‐eicosane, were synthesized by using interfacial polymerization method with toluene‐2,4‐diisocyanate (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Poly(ethylene glycol)octyl‐phenyl ether (OP), a nonionic surfactant, was the emulsifier for the system. The experimental result indicates that TDI was reacted with DETA in a mass ratio of 3 to 1. FT‐IR spectra confirm the formation of wall material, polyurea, from the two monomers, TDI and DETA. Encapsulation efficiency ofn‐eicosane is about 75%. Microcapsule ofn‐eicosane melts at a temperature close to that ofn‐eicosane, while its stored heat energy varies with core materialn‐eicosane when wall material fixed. Thermo‐gravimetric analysis shows that core materialn‐eicosane, micro‐n‐eicosane and wall material polyurea can withstand temperatures up to 130, 170

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220502

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractRapid parallel liquid‐phase synthesis of pyrazoles has first been developed. The 1,3‐dipolar cycloaddition between nitrilimines generatedin situand soluble polymer‐supported alkynyl or alkenyl dipolarophiles in parallel one‐pot fashion gave the corresponding PEG‐supported regioisomeric pyrazoles or regiospecific pyrazolines. The latter was assuredly oxidated by DDQ to PEG‐supported regiospecific pyrazoles. Cleavage from the support under mild conditions afforded pyrazoles in good yields and

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220503

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractHomocoupling of aryl iodides catalyzed by cyclopalladated complexes of tertiary arylamines gives symmetric biaryls with good yields in DMA or ionic liquid [Bmim]BF4. This catalytic alternative of the Ullmann reaction has proved to be sensitive to both electronic and steric factors of substrates.

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220504

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractPromotion of ionic liquid, 1‐ethyl‐3‐methylimidazolium bromide (emimBr), to the synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide in the presence of potassium carbonate and less amount of methyl iodide under mild conditions was investigated. The results showed that the high selectivity and raised yield of DMC was achieved due to the addition of emimBr in the reaction system. And effect of several reaction conditions such as Temperature, pressure and amount of emimBr was disc

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220505

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractThe structures of barbituric acid derivatives substituted with Schiff base were optimized usingab initioHF method at 6‐31G basis set. Based on the optimized structures, the electronic spectra were obtained by INDO/CI method. The second‐order nonlinear optical (NLO) coefficients βμ were calculated according to the sum‐over‐states (SOS) formula. In addition, the effect of conjugation on electronic specra and second‐order NLO coefficients was investigated. The influence of exchange between C and N atoms as well as the substituted effect on the barbituric acid was discussed. It was indicated that the exchange between C and N atoms on Schiff base is important for enhancing the NLO coefficient of the whole molecule with donor and acceptor (D‐A). Meanwhile significant changes in electron donation and acception were observed as substituents changes positions. Among the designed models, molecule lb has maximal βμ value of 124.65×10−‐30esu. About molecule lb, barbituric acid is considered as an accepted electronic group and the position of N atom on Schiff

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220506

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractThe two possible reaction paths of producing ethane on coupling reaction of methane through plasma were theoretically investigated by B3LYP and MPF2 methods with 6‐311G* respectively and further compared with the previous results calculated from B3LYP/6‐31G*. The new investigated results consistently confirmed the previous conclusion. And the influences of the calculation methods and basis sets on the calculated results were also discus

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220507

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractA new niobate compound with the chemical composition of Ba5LiTiNb9O30was synthesized by doping Li+into the system BaO‐TiO2‐Nb2O5in conventional solid state reaction method. The crystalline structure was determined by X‐ray dilation analysis (XRD). The results showed that crystal structure of Ba5LiTiNb9O30belongs to tetragonal tungsten bronze structure with space group P4bmand its unit cell parameters:a=b=1.2512(2) nm,c=0.4008(5) nm. The microstructure of reaction products was observed by scanning electron microscopy

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220508

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractThe luminescence properties of aluminate sodalite Ca8[Al12O24](WO4)2(CAW) un doped and doped with Tb3+are reported and discussed. At morn temperature the emission of tetrahedral WO42‐in CAW showed an abnormally small Stokes shift (9060 cm−1), which is related to the crystal structure of CAW. A strong absorption band in the excitation spectrum of the Tb3+‐activated CAW is ascribed to the absorption of the charge transfer state Tb4+‐W5+, into which the excitation resulted in the efficient emission from the5D4level of Tb3+, but not from the5

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220509

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractThe cadmium selenide quantum dots (QD) have been synthesized by template‐control in an emulsion liquid membrane system. The system consisted of kerosene as solvent, L152 (dialkylene succinimide) as surfactant, N7301 (trialiphatic amine, Ra, R=C8‐C10) as carrier, 0.1 mol/L CdCl2solution as internal‐aqueous phase and H2Se gas as external phase. Additive organic template agent in internal‐aqueous phase was necessary to fom CdSe QD. The influence of the nature of template and its concentration on sizes of the formed CdSe QD has also been studied. Transmission electron microscopy showed that the sizes of the products could be controlled down to 3‐4 nm. X‐ray diffraction analysis revealed that the crystals had cubic structure. The formation process and the optical properties of CdSe QD have also bee

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220510

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractNanometer‐sized fluorescent particles (poly‐4‐vinylaniline nanoparticles) have been prepared under ultrasonic radiation. The fluorescence of poly‐4‐vinylaniline nanoparticles (PVN) isca. 50 folds higher than that of 4‐vinylaniline. In comparison with single organic fluorophores, these nanoparticle probes are brighter, more stable against photobleaching, and do not suffer from blinking of light emission. A new fluorimetric method for the determination of reduced glutathione (GSH) has been developed with poly‐4‐vinylaniline nanoparticles as a probe. The maximal fluorescence for the reagent occurs at excitation and emission wavelengths of 306 and 380 nm, respectively. Under optimal conditions, PVN reacts with GSH ando‐phthalaldehyde (OPA) to give a highly fluorescent derivative in Na2CO3‐HCl buffer (pH= 10.55). The fluorescence excitation and emission wavelengths of the fluorescent derivative are located at 340 and 428 nm, respectively. The relative fluorescence intensity (RF) is linear in the range of the GSH concentration from 3.0 × 10−7to 1.2 × 10−5mol/L. The method has been applied to the determination of GSH in synthetic samples

ISSN:1001-604X    

DOI:10.1002/cjoc.20040220511

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY