摘要:

AbstractPresent paper discusses the behaviour of transfer free energy of some amino acids from water to aqueous solution of Ethanol, 2‐PrOH ad t‐BuOH at different compositions. Dissection of transfer free energy into cavity term, interaction term and electrical term reveals that cavity forming free energy of transfer ΔGt0(Cav.) plays an important role in dictating actual interaction of amino acids in these mixed solvents. Cavity forming free energy of transfer has been estimated by using Scaled Particle Theory (

ISSN:0009-4536    

DOI:10.1002/jccs.200400001

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractA new analytic method for the determination of gibberellic acid (GA) by perturbation causing different amounts of GA on the BZ oscillating chemical system involving the Mn(II)‐catalyzed reaction between L‐alanine, potassium bromate, and malonic acid in the acidic medium is proposed. The method relies on the linear relationship between the change in the oscillating period of the chemical system and the concentration of GA, which is in this work exposed for the first time. The calibration curve is linearly proportional to the concentration of GA over the range 1.0 × 108−1.0 × 10−6M, where the regression coefficient is 0.9998, and the detection limit is 5.0 × 10−9M of GA. Some aspects of the potential mechanism of action of GA on the BZ oscillating chemical system are discuss

ISSN:0009-4536    

DOI:10.1002/jccs.200400002

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractMulticenter electric multipole moment integrals over Slater type orbitals with integer and noninteger principal quantum numbers are expressed in terms of overlap integrals. The computer results for the integer case agree best with the prior literature. The accuracy of the computer results for noninteger case is not compared with the literature due to the lack of relevant literature, but the limit of the noninteger case is compared with the integer case and good agreement is achieved for wide changes in the relevant molecular parameters.

ISSN:0009-4536    

DOI:10.1002/jccs.200400003

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractThis paper reports the utilization of solid phase extraction and the reversed‐phase high‐performance liquid chromatography (RP‐HPLC) for the determination of six transition metal ions (iron, cobalt, nickel, copper, zinc and manganese) in biological samples. The samples were digested by microwave digestion. The iron, cobalt, nickel, copper, zinc and manganese ions in the digested samples can react with 2‐(2‐quinolinylazo)‐5‐diethylaminophenol (QADEAP) to form colored chelates in pH 4.0 acetic acid‐sodium acetic buffer solutions and cetyl trimethylammonium bromide (CTMAB) medium. These chelates were enriched by solid phase extraction with C18cartridge. Then the chelates were separated on a Waters Nova‐Pak‐C18column (3.9 × 150 mm, 5 μm) by gradient elution with methanol (containing 0.5% of acetic acid and 0.1% of CTMAB) and 0.05 mol/L pH 4.0 acetic acid‐sodium acetic buffer solution (containing 0.1% of CTMAB) as mobile phase at a flow rate of 0.5 mL/min. The detection limits of iron, cobalt, nickel, copper, zinc and manganese are 3 ng/L, 4 ng/L, 2 ng/L, 4 ng/L, 8 ng/L, 10 ng/L, respectively. This method was applied to the determination of iron, cobalt, nickel, copper, zinc and manganese in biological sa

ISSN:0009-4536    

DOI:10.1002/jccs.200400004

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractA novel cyan‐bridged macrocyclic nickel complex [{NiL1}{Fe(bipy)(CN)4}]2·5H2O1(L1= 3,10‐dimethyl‐1,3,6,8,10,12‐hexaazacyclotetradecane, bipy = 2,2‐bipyridine) was synthesized and structurally characterized. The complex exhibits one‐dimensional zigzag chain structures. Each ferrous(II) ion connects two nickel(II) ions using twotransCN−groups, and the remaining CN−groups are terminal. Magnetic measurement shows weak ferromagnetic interaction between the nearest Ni(II) ions through the diamag

ISSN:0009-4536    

DOI:10.1002/jccs.200400005

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractThe η1‐thiocarbamoyl palladium complexes [Pd(PPh3)(η1‐SCNMe2)(η2‐S2R)] (R = P(OEt)2,2; CNEt2,3) andtrans‐[Pd(PPh3)2(η1‐SCNMe2)(η1‐Spy)],4, (pyS: pyridine‐2‐thionate) are prepared by reacting the η2‐thiocarbamoyl palladium complex [Pd(PPh3)2(η2‐SCNMe2)][PF6],1with (EtO)2PS2NH4, Et2NCS2Na, and pySK in methanol at room temperature, respectively. Treatment of1with dppm (dppm: bis(diphenylphosphino)methane) in dichloromethane at room temperature gives complex [Pd(PPh3)(η1‐SCNMe2)(η2‐dppm)] [PF6],5. All of the complexes are identified by spectroscopic methods and complex1is determined by

ISSN:0009-4536    

DOI:10.1002/jccs.200400006

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractFourier‐transform infrared spectroscopy has been employed to investigate the adsorption and photo‐oxidation of CH4over powdered TiO2. The interaction between the CH4and TiO2surface is weak. It is found that no CH4molecules are adsorbed on the surface at 35 °C in a vacuum. Under UV irradiation, CH4decomposes to form CO(a), CO2(g), H20(a), and HCOO(a)in the presence of O2. The photoreaction rate is retarded and only small amounts of CO(a)and HCOO(a)are formed in the absence of O2. It is observed that the oxygen atoms of O2are incorporated into these photoproducts as18O2is used. The major18O‐containing products are C18O(a), C18O2(g), H218O(a), HC16O18O(a), and HC18O18O(a)after 180 min UV irradiation. However, the extent of18O incorporating into the adsorbed formate is dependent on UV irradiation time. In the early stage of UV irradiation HC16O16O(a)is the major formate form indicating the involvement of TiO2lattice oxygens for its formation, but HC18O18O(a)becomes the major one after 180 min indicating the involvement of18O2. Formate on TiO2further photodecomposes to CO2(g), but not to CO(a). CO(a)formation is directly from CH4photodecomposition with the participation of TiO2lattice oxygens

ISSN:0009-4536    

DOI:10.1002/jccs.200400007

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractThe reaction of Co(NO3)2·6H2O with two equivalents of PPz (PPz = piperazine hexahydrate) and two equivalents of NH4SCN in CH3OH afforded the complex [Co(NCS)2(PPz)2(CH3OH)2]. The reaction of Ni(NO3)2·6H2O with two equivalents of PPz and four equivalents of NH4SCN in CH3OH afforded the complex [Ni(NCS)4(PPz)2]. Their IR spectra have been recorded and the structures have been determined. Crystal data for1: space group P&1bar;, a = 6.7208(6) Å, b = 8.4310(8) Å, c = 8.5923(8) Å, a = 77.881(2)°, β = 76.342(2)°, γ = 83.936(2)°, V = 461.75(1) Å3, Z = 1 with final residuals R1 = 0.0650 and wR2 = 0.1725. Crystal data for2: space group P2(1)/n, a = 7.4209(6) Å, b = 11.0231(9) Å, c = 12.317(1) Å, β = 96.642(9)°, V = 1000.9(2) Å3, Z = 2 with final residuals R1 = 0.0378 and wR2 = 0.0809. Important NCS—H‐N and O‐H—N(PPz) hydrogen‐bonding interactions in compound1and NCS···H‐N hydrogen‐bonding interactions and NCS—SCN interactions in compound2play a significant role in aligning the po

ISSN:0009-4536    

DOI:10.1002/jccs.200400008

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractUsing the mixture of cetyltrimethylammonium bromide (CTAB) and p‐Octyl polyethylene glycol phenyl ether (OP‐10) as templates, siliceous MCM‐48 materials can be synthesized with low molar ratio of CTAB to silica (0.139:1) and low concentration of mixed surfactants (ca.5%) and within a wide range of OP‐10/CTAB ratio (0.08˜0.25). The materials were characterized by X‐ray powder diffraction, N2adsorption/desorption isotherm, TEM, TG‐DSC and29Si MAS NMR. Measurements indicated that the use of mixed surfactants allowed better condensation and higher ordering of the cubic mesostructure; at the same time, some properties of these materials were sensitive to the OP‐10/CTAB ratio. It was also found that the reduced pH of the gel which had been crystallized for a certain time gave a highly reproducible synthesis with a high silica yield (about 95%). Furthermore, the reaction mechanism of the synthesis is discu

ISSN:0009-4536    

DOI:10.1002/jccs.200400009

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY

摘要:

AbstractStable films made from chitosan (CS) on pyrolytic graphite (PG) electrode gave direct electrochemistry for incorporated enzyme nitrate reductase (NR). Cyclic voltammetry (CV) of NR‐CS films showed a pair of well‐defined and nearly reversible redox peaks at about −0.430 V vs. SCE at pH 7.0 phosphate buffers, which was considered as the redox of FAD and heme‐ion. The electron transfer between NR and PG electrode was greatly facilitated in CS films. Integration of reduction peaks at different scan rates from 0.01 to 0.5 V s−;1gave nearly constant charge values, which is characteristic of thin‐larger‐electrochemical behavior. The pH of the solution strongly affected the direct electron transfer of NR‐CS films. EDTA accelerated the electron transfer, and it was proposed as a stimulant for the system. Reflectance absorption infrared spectra demonstrated that NR retained a nearly native conformat

ISSN:0009-4536    

DOI:10.1002/jccs.200400010

出版商:WILEY‐VCH Verlag    

年代:2004

数据来源: WILEY