Synthesis and Crystal Structure of 4-Phenyl-5-(1''''t-butyl-5''''-methyl-4''''-pyrazolyl)-1,2,4-triazol-3-thione

COOEtCOCH3(CH3)2NNHNH2NNCH3OOEtNH2NH2NNCH3ONHNH2PhNCSNNCH3ONHNHCNHSOH-NNCH3NNHNPhS12345 1 INTRODUCTION A large number of 1,2,4-triazole derivatives have been synthesized in recent years[1～4]. Many of them are reported to exhibit broad spectrum biologi-…     

Isolation and Crystal Structure of Trans-2,2'''',4,4''''-tetramethyl-6,6''''-dinitro Azobenzene

1 INTRODUCTION The aconitum plants produce various diterpene and norditerpene alkaloids[1, 2]. Up to now more than 450 diterpenoid and norditerpenoid alkaloids have been isolated from the roots of this genus[3]. Sub- sequent studies on the flower of the same subspecies were directed to the other secondary metabolites such as flavonoids[4, 5]. The flavonoidic composi- tions of several oriental species of A. plants have been reported[6～8]. A. sungpanense hand. Mazz., a very highly poi- s…     

Synthesis, Characterization and Structure of the Dimmer Complex [Ni(TSSB)(phen)H_2O]·C_2H_5OH·0.5H_2O

1 INTRODUCTION Schiff base complexes containing sulfur and com- plexes of amino acid Schiff bases[1～5] have recently aroused increasing interest because of their antiviral, anticancer and antibacterial activities. Taurine, an amino acid containing sulfur, is indispensable to human beings and has important physiological func- tions. Recently, we have found that the Shiff base derived from taurine has manifold coordination modes[4～10]. Aromatic-ring stacking interaction is an important …     

Potential energy surfaces of an adenine-thymine base pair and its methylated analogue in the presence of one and two water molecules: molecular mechanics and correlated ab initio study

Potential energy surfaces of monohydrated and dihydrated adenine-thymine and 9-methyladenine-1-methylthymine base pairs were examined by the molecular dynamics/quenching technique using the Cornell et al. force field (J. Am. Chem. Soc. 1995, 117, 5179). Long runs of molecular dynamics/quenching calculations allowed us to evaluate the free energy surface. The most stable and populated structures found were fully reoptimized at the correlated ab initio level employing the resolution of identity M?ller-Plesset method. A systematic study of the base pairs' microhydration using both the empirical and the high-level correlated ab initio approaches is presented for the first time. We show that the occurrence of water molecules and their gradually increasing number as well as the methylation of the bases favor stacked structures over the planar hydrogen-bonded ones. These results based on the correlated ab initio calculations are in the excellent agreement with data obtained from our previous empirical potential molecular dynamics study (Kabelác et al. Chem.-Eur. J. 2001, 7, 2067).     

Multinuclear NMR Study of the Structure and Intramolecular Dynamics of (eta(2)-Acetone phenylhydrazonato)tetrafluorooxotungsten(VI)

Using one- and two-dimensional techniques of (1)H, (13)C, (15)N, and (19)F NMR spectroscopy, it was proved that acetone phenylhydrazone (H-aph) acts as a two-center N,N-donor ligand in the complex [WOF(4)(aph)](-). As a result of the coordination to tungsten, the ligand conformation changes from E to Z, and at the same time the phenyl ring is turned out of the >N-N=C< plane. At low temperatures (-30 degrees C), the equatorial plane of the pentagonal-bipyramidal tungsten polyhedron comprises two donor nitrogen atoms of hydrazone and three fluoro ligands. At elevated temperatures, stereoisomeric interconversion caused by hindered intramolecular rotation of the aph(-) ligand occurs. The mechanism of this process was elucidated on the basis of the dynamic effects in (19)F spectra and line-shape analysis of the trans-CH(3) resonance in (13)C spectra split due to direct "through-space" coupling with the proximate fluoro ligand.     

Extraction of some transition metals with N,N-dibutyl-N'-benzoylthiourea into molten paraffin at 65 degrees C

The solid-liquid extraction behaviour of some transition metals (Cu(II), Co(II), Ni(II), Cd(II) and Pb(II)) by the use of N,N-dibutyl-N'-benzoylthiourea as an extractant in paraffin (58-60 degrees C) has been investigated at 65.0+/-0.5 degrees C. The effect of equilibration time, pH of the aqueous phase, concentration of extractant and solid solvent used on the extraction efficiency of these metals have been discussed. The interferences of various ions are examined. The method has been applied to the determination of these metals in synthetic samples, mushrooms and sediment.     

Estimation of n-Octanol/water Partition Coefficients （lgKow） and the Aqueous Solubility （-lgSw） of all PCDF Congeners by Density Functional Theory

1 INTRODUCTION As is widely known, PCDFs together with poly- chlorinated dibenzo-p-dioxins (PCDDs) and poly- chlorinated biphenyls (PCBs) have been included in many blacklists, such as “persistent organic pol- lutants (POPs)” and suspected “environmental en- docrine disruptors (EEDs)”. This is because PC- DFs are chemically and thermally stable and com- plex PCDF mixtures are generally resistant to bio- degradation. Although the concentration of these chemicals is quite low o…     

Novel glucose non-interference biosensor for lactose detection based on galactose oxidase-peroxidase with and without co-immobilised beta-galactosidase

Two types of amperometric biosensors for lactose detection based either on co-immobilisation of two enzymes (galactose oxidase with peroxidase) or co-immobilisation of three enzymes (beta-galactosidase, galactose oxidase and peroxidase) were constructed. A graphite rod with pre-adsorbed ferrocene was used as a working electrode. The use of galactose oxidase instead of the frequently used glucose oxidase resulted in the construction of a glucose-non-interfering lactose sensor. Co-immobilisation of peroxidase with galactose oxidase allowed the effect of borate on the extension of the linear range and the effect of the working potential on galactose oxidase activation to be studied. The presence of beta-galactosidase greatly enhances the sensor's sensitivity, but its linear range is narrower than that of the sensor without beta-galactosidase. Addition of DEAE-dextran and inositol to the enzyme layer improved the half-life more than 16-fold compared with the sensor without stabilisers. A response time between 60 and 75 s (90% of the steady-state value) and a detection limit for lactose determination from 44 to 339 microM (signal-to-noise ratio = 3) were observed depending on the conditions. The precision of measurements of standard lactose solution for the trienzymatic and bienzymatic sensors was 2.19 and 2.02%, respectively. The precision of analysis of dairy products varied from 0.24 to 5.24%. Analyses of real samples showed good correlation with HPLC analysis; eight samples and 10 standard lactose solutions without pre-treatment were analysed in 1 h.     

Synthesis and Structure of anti-Configuration Complex [Cu(tssb)_2]·2[(H_3O)Cl]·4H_2O

1 INTRODUCTION The complexes of amino acid Schiff base have attracted considerable attention because of their bio- activities[1, 2]. Taurine is a special amino acid in be- ings, and recently the complexes of taurine conden- sation salicylaldehyde Schiff …