摘要:

AbstractIn this paper, we carry out the calculation on the system (X@C60)(X=Li, Na, K, Rb, Cs; F, C1, Br, I), where the position ofXchanges along 5 typical symmetry directions. For the calculation of quantum chemistry we use EHMO/ASED method, for the calculation of molecular mechanics we uee Buckingham potential (exp‐6‐1) function, and for the calculation of thermo‐chemical cycle we use individually isolating the processes such as the structure variation, charge transfer and charge distribution, and their interactions etc. The calculation results show that (1) In the region of radius τ≈0.2 nm of the C60cage, the potential field is nearly spherical; (2) Except for Li and Na, the systems are the most stable with minimum energies at the center of C60cage. For Li and Na, the systems are the most stable with minimum energies at τ≈0.16 run and τ≈0.13 nm, respectively. In view of the interactive region of chemical bonds, the interactions between X and the C60cage do not belong to the classical chemical bonds; (3) The non‐bonding interaction between the X and C60cage are not purely electro‐static, in which the electro‐static interactions only occupy ∼90% at mat on an average. The repulsion owing to the overlap of the electron cloud and the attraction owing to the dispersion can not be neglected. These two interactions determine the variations of size and trend of the system energies with r; (4) The polarization due to the position of X deviating from the center of C60cage plays an important role at the moat stable

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160302

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

年代:1998

数据来源: WILEY

摘要:

AbstractThe electronic and molecular structures of the monomer and dimer of trimethylaluminium have been studied using density functional theory andab initioMP2 method. The optimized geometry of the monomer Al(CH3)3is of C3hsymmetry, whew that of the dimer [Al(CH3)3]2contains a carbon‐bridged four‐membered ring structure with C2hsymmetry. The hydrogen‐bridged six‐membered ring structure is found to be unstable. The calculated dimerization energy for the four‐membered ring structure is 78 kJ/mol, in close proximity to the experimental due of 85.

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160303

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

年代:1998

数据来源: WILEY

摘要:

AbstractAb initiocalculations have been used to study the decomposition pathways of monofluromethanol. Equilibrium geometries and transition state structures were optimized at the HF/6‐31G(d) and MP2/6‐31G(d) levels. Single point energies were obtained at different levels of theory. The most favorable reaction to dissociation is the 1,2‐HF elimination which is consistent with the experimental re

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160304

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

年代:1998

数据来源: WILEY

摘要:

AbstractA piezoelectric immunosensor has been developed for the detection of complement C4. Anti‐C4 antibody was immobilized onto the gold electrodes of a 9 MHz AT‐cut piezoelectric crystal. The coated crystal with the physical adsorption method to immobilize antibody showed the better results than the polyethyleneimine adhesion, glutaraldehyde cross‐linking method with respect to sensitivity and reproducibility. The antibody‐bound crystal with the physical adsorption method was successfully used for the detection of human complement C4 in the concentration range of 0.1—10 μg/mL for 40 min incubation time. The immunosensor system had good selectivity, and other materials in human Serum did not interfere the detection remarkably. The crystal could be regenerated nearly 15 times when the bound materials on the crystal surface were eluted by strong acid and strong alkali solutions and subsequently cleaned in a ultrason

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160305

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

年代:1998

数据来源: WILEY

摘要:

AbstractApplication of parallel and serial dual electrode detectors for capillary electrophoresis was first described. In parallel dual electrode approach, two 100 μm‐diameter Cu disks arranged side by side were used as the dual working electrode for the simultaneous determination of a mixture of carbohydrates and amino acids. In serial dual electrode approach, two working electrodes were arranged in a disk‐ring manner for the simultaneous determination of both cysteine and cystine; the disk electrode was Hg/Au serving as the upstream electrode, the ring electrode was 5% CoPC carbon paste serving aa the downstream elect

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160306

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

年代:1998

数据来源: WILEY

摘要:

AbstractThe mass transport and charge transfer kinetics of ozone reduction at Nafion coated Au electrodes were studied in 0.5 mol/L H2SO4and highly resistive solutions such as distilled water and tap water. The diffusion coefficient and partition coefficient of ozone in Nafion coating are 1.78×10−6cm2·s−land 2.75 at 25°C (based on dry state thickness), respectively. The heterogeneous rate constants and Tafel slopes for ozone reduction at bare Au are 4.1×10−6cm·s−1, 1.0×10−6cm·s−1and 181 mV, 207 mV in 0.5 mol/L H2SO4and distilled water respectively and the corresponding values for Nafion coated Au are 5.5×10−6cm·s−l, 1,1×10−6cm·s−1and 182 mV, 168 mV respectively. The Au microelectrode with 3 μm Nafion coating shows good linearity over the range 0–10 mmol/L ozone in distilled water with sensitivity 61 μA·ppm−1·cm−2, detection limit 10 ppb and 95% response time below 5 s at 25°C. The temperatur

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160307

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

年代:1998

数据来源: WILEY

摘要:

AbstractFive chiral stationary phases (CSPs) were used to separate the enantiomers of a series ofO,O‐diethyl (p‐methyl‐benzenesulfonamindo)‐aryl(alkyl)‐methylphosphonates. A chiral recognition mechanism was presented to explain the resolution of these compounds. Results show that CSP with strong π‐acceptor 3,5‐dinitrobenzoyl group and high steric hindrance has the best resolution ability in chiral separation ofO,O‐diethyl (p‐methylbenzenesulfonamindo)‐aryl(alkyl)‐methylphosphonates. When a CSP has just a strong π‐acceptor 3,5‐dinitrobenzoyl or high steric hindrance it does not have good chiral resolution ability. The chiral recognition is more difficult when the CSP has more

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160308

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

年代:1998

数据来源: WILEY

摘要:

AbstractPhosphatidylcholines (Ln's) and their neutral analogs 1,2‐diacyl‐sn‐glycerol‐3‐phosphoric acid bromoethyl esters (Pn's) have been found to exhibit different aggregation behaviors brought about by hydrophobic‐lipophilic interactions (HLI) by means of kinetic probe in MeOH‐H2O binary aquiorganic systems. The effects of the structure and the environment on the interesting aggregation of the amphiphilic molecules

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160309

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

年代:1998

数据来源: WILEY

摘要:

AbstractHomochiralcis, cis‐; cis,transandtrans,trans‐spiro[4,4]‐nonane‐1,6‐diols were prepared via diastereoselective reduction of enantiomerically pure spiro[4.4]nonane‐l,6‐dione (1) with the corresponding reducing agents: lithium n‐butyldiisobutylaluminium hydride forcis,cis‐diol (2) with 88% yield; BH3·THF for cis,trans‐diol (8) with 91% yield; LiAlH4fortrans,trans‐d

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160310

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

年代:1998

数据来源: WILEY

摘要:

AbstractHalogenation of the potassium or silver salts of bis(trifluoromethanesulfonyl)methane (CF3SO2)2CH2and its cyclo analogues 1 withN‐fluoro‐bis(trifluoromethanesulfonyl)imine [(CF3SO3)2NF], chlorine or bromine gave good yields of the corresponding α‐halo disulfone (CF3SO2)2CHX and cyclo analogues 9, 10. The chemical transformation of these fluorinated α‐halo‐disulfones ar

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160311

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

年代:1998

数据来源: WILEY