水溶性稠杂环均三唑并噻二唑体系的合成及生物活性(I): 哌嗪取代衍生物

4-氨基-5-吡啶-4-基-均三唑硫醇(1)在复合催化剂DMAP和TBAB作用下与对卤代苯甲酸经环缩合反应以高收率得到中间体6-(5-氯-3-甲基-1-取代苯基-1H-吡唑-4-基)-3-吡啶-3-基-均三唑并[3,4-b][1,3,4]噻二唑(2a～2c), 接着苯环卤原子与取代哌嗪在聚乙二醇催化作用下发生亲核取代反应得到相应的哌嗪游离碱(3a～3c). 其中, 单取代哌嗪游离碱3a与含功能基的卤代物缩合得到功能基取代的哌嗪衍生物(4a～4g). 这些产生的游离碱与盐酸反应得到相应的水溶性盐酸盐. 所合成新化合物的结构经元素分析和光谱数据表征, 并评价了它们的体外抗菌活性及构效关系.     

Some aspects of polymer colloids I. Preparation and properties of different types of latex particles

The boundary region separating a latex particle from the surrounding medium has a great influence on the properties of latex dispersions. Four types of polystyrene and polystyrene/comonomer latices differing greatly in the structure of the boundary region were prepared. The first part of a series of papers reports on the preparation of the various latex dispersions. Mean particle sizes were obtained from simple turbidity measurements, quasi-elastic light scattering, and electron micrographs. The behavior of the particles in the centrifugal force field is a simple tool for detecting aggregation tendencies that are not directly related to salt stability. The BET-surface area agrees with the area calculated from the mean particle size when a sharp boundary and smooth surface is developed between the particle and the surrounding medium. In the case of particles with extended boundary regions (core/shell particles or particles with hairy envelopes), film formation reduces the specific surface area. Removal of soluble oligomers and polymers from the boundary region during subsequent treatments (purification and centrifugation before freeze-drying) can increase the surface area considerably.     

Theoretical studies on quinones I. The structure of p-benzoquinone and two of its excited triplet states

Ab initio calculations on the ground and two excited triplet states (³B_1g and ³B_1u) of p-benzoquinone are described. The geometries of the three states were fully optimised at the SCF level using the 3-21G basis set. For the excited states, both D_2h and C_2v geometries were investigated. Comparison was made between UHF and ROHF levels of theory.     

Studies of polymer solvation by dielectric relaxation spectroscopy I: polyvinyl pyrrolidone in propylene carbonate,dimethyl sulfoxide and tetramethyl urea

The dielectric relaxation behavior of the title solutions of PVP 40000 is measured in the frequency domain (50 MHz to 36 GHz) at 20 °C. The polymer content of the solutions (up to 0.25 mole fraction of monomer units) is such that it does not yet contribute significantly to dielectric loss. The solvent relaxation shows in all cases a bulk and a slowed down contribution, both characterized by concentration-independent relaxation times. The slow contribution is ascribed to the solvate. Solvation numbers for dilute solutions roughly range between 2 and 4 per PVP repeat unit.     

Nuclear quadrupole resonance investigations of clathrate compounds: I. The35Cl resonance ofp-dichlorobenzene in various clathrate systems

The³⁵Cl nuclear quadrupole resonance spectra ofp-dichlorobenzene in several clathrates are reported in the temperature range 77 K to room temperature. The information provided by this technique as to the nature of the guest-host interactions is discussed in the light of these results and it is concluded that NQR represents a useful technique in this context.     

The modification of the triple helical structure of gelatin in aqueous solution I. The influence of anionic surfactants,pH-value,and temperature

The modification of the triple helical structure in aqueous gelatin solutions by changing pH and adding alkyl sulphates at 298 K and after rechilling the solution to 283 K was investigated by CD-measurement. At 298 K the triple helical content at the IEP of the gelatin has its maximum value. It is only weakly affected by adding sodium dodecyl sulphate (SDDS) at concentrations <10^–4 M/dm³. The unfolding of the triple helix affected by pH and SDDS is reversible by rechilling the solution. The triple helical content of gelatin solutions decreases at SDDS concentrations higher than 10^–4 M/dm³. In all cases the decrease of the amount of triple helical structure is connected with an increase of the cis-configuration in single chains and leads to chain reversals. At sufficiently high SDDS concentrations-sheets are formed. These changes are thermally irreversible. Sodium decyl sulphate (SDS) has a more minor influence than SDDS except in the range of the c.m.c. of SDS. At sufficiently high SDS concentrations,-turns appear.     

The dissociation constant of amino acids by the conductimetric method: I. pK 1 of MOPSO-HCl at 25°C

The dissociation constants of amino acids are generally determined by acid-base titration and by the emf method. The use of the conductimetric method to obtain pK for amino acids appears to be the first of its kind. In this study, we describe the method of measurement, the treatment of the data and discuss the results. The choice of MOPSO for the investigation is in conjunction with the development of new buffer systems as pH Standard Reference Materials. The value for pK at 25°C is 0.060±0.005.     

Another approach to the interpretation of various macrophenomena simulated in terms of the properties of the model bodies involved in them and their elementary interactions. I. Gaseous media

In this study attention has been focused on the physical nature of molecular interactions regarded as the function of various properties of the involved molecules and giving rise both to individual pressure impulses () and to variations of their frequency at a constant gas concentration and temperature. The corresponding elementary thermal interactions () have also been taken into account. The quantities and are considered to be of the same physical nature but of different magnitudes. The empirical Van der Waals equation of state for the real gases has been reinterpreted in terms of the elementary interactions. The theoretical predictions following from the developed approach have been compared with and satisfactorily confirmed by the corresponding experimental data available in the relevant literature.     

Binding of naproxen and 1-anilino-8-naphtalenesulphonic acid to albumin: Characterization of their binding sites in bovine serum albumin

The binding of naproxen (NP) and 1-anilino-8-naphtalenesulphonic acid (ANS) to bovine serum albumin (BSA) has been studied by equilibrium dialysis and spectrophotofluorometry, respectively. The drug protein (D/P) ratio is found to determine the nature of binding sites for NP but not for ANS. At low D/P ratio, NP possesses a specific site in BSA and one of the tryptophan residues is part of it. Fluorometric investigation reveals non-displacement of ANS from its sites by the binding of NP to its specific site. At high D/P ratio, NP instead causes localized conformational changes in BSA. Furthermore, it is possible to infer the location of NP's specific site as loop 4 of BSA. NP and ANS binding sites have also been examined by employing Bromocresol Green (BCG) as a spectrophotometric probe. Competition studies are also able to establish distinct binding pattern for the two ligands in BSA. The displacement pattern points out the presence of independent sites for NP (specific site) and ANS (initially occupied site) in BSA in spite of their amphipathically similar nature.     

Speed of sound and isentropic compressibilities of nonelectrolyte liquid mixtures. I. Binary mixtures containingp-dioxane

The speed of sound was measured for mixtures of p-dioxane with cyclohexane, n-hexane, benzene, toluene, carbon tetrachloride, chloroform, 1,1,2,2-tetrachloroethane, pentachloroethane and ethyl acetate over the whole mole fraction range at 30°C. These data were combined with densities and molar volumes to obtain isentropic compressibilities and Rao's molar sound functions. Excess isentropic compressibilities and excess speeds of sound have also been calculated. The behavior of the present mixtures is discussed in terms of possible molecular interactions and the Prigogine-Flory-Patterson theory of liquid mixtures.     

α- and β-cyclodextrin complexes with n-alkyl carboxylic acids and n-alkyl p-hydroxy benzoates. A molecular mechanics study of 1:1 and 1:2 associations

Molecular mechanics (MM) methods were employed to evaluate stabilization upon formation of inclusion compounds between two different guest molecules and α- and β-cyclodextrins (CDs) for two different stoichiometries 1:1 and 1:2. The two guest molecules studied were n-alkyl carboxylic acids and n-alkyl p-hydroxy benzoates with variety of chain lengths. The computed stability for the inclusion compounds between α-CDs and n-alkyl carboxylic acids reproduced experimental data reported in the literature. The transition between 1:1/1:2 complexes occurred at an alkyl chain length of n_C=9. It was previously demonstrated by diffusion coefficients measures that a stable 1:2 stoichiometry inclusion compound could be formed between n-alkyl p-hydroxy benzoates and α-CD for the chain length n_C>4. The computed results reproduced the experimental ones. The combination between OPLS and GB/SA resulted in better agreements with experiments than those obtained with MM2 and MM3.     

Phase behavior and dynamic properties in mixed systems of anionic and cationic surfactants: lithium perfluorooctanesulfonate/diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) and lithium dodecyl sulfate/DEFUMAC aqueous mixtures

Two ternary phase diagrams of the cationic perfluorosurfactant diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) with an anionic perfluorosurfactant lithium perfluorooctanesulfonate (LiFOS) and an anionic hydrocarbon surfactant lithium dodecyl sulfate (LiDS) have been established at 25°C. The total surfactant concentration was less than 20wt%. In a wide mixing region of the LiFOS/DEFUMAC system, a lamellar-type phase,P , was identified by its texture under a polarization microscope and by its x-ray diffraction pattern. Dispersed fragments ofP -phase are present in the dilute solutions in which one surfactant was in excess. The anisotropy of electrical conductivity, flow birefringence, dynamic light scattering, and electric briefringence demonstrate that theP fragments are disk-like with a radius of 0.7 m. The disk-likeP particles are transformed by shear into a spherical aggregate ofL above a critical shear gradient. LiDS/DEFUMAC mixed solution forms dispersed and precipitatedL in the dominant region. Radius and micropolarity of the dispersedL aggregates are decreased as the ratio of LiDS:DEFUMAC approaches 1:1. On the basis of x-ray diffraction measurement the structure of precipitatedL -phase seems to consist of monolayers.     

Standardized basis sets for high-level-correlated relativistic calculations of atomic and molecular electric properties in the spin-averaged Douglas-Kroll (no-pair) approximation I. Groups Ib and IIb

Summary The technique developed earlier for the generation of the so-called first-order polarized basis sets for accurate non-relativistic calculations of molecular electric properties is used to obtain similar basis sets suitable for calculations in the Douglas-Kroll no-pair approximation. The corresponding (relativistic) basis sets are devised for atoms of the Groups Ib and IIb of the periodic table and tested in calculations of atomic polarizabilities and dipole moments of the coinage metal hydrides. Excellent performance of these basis sets has been found in the case of molecular calculations.     

Fast high-throughput method for the determination of acidity constants by capillary electrophoresis: I. Monoprotic weak acids and bases

A new and fast method to determine acidity constants of monoprotic weak acids and bases by capillary zone electrophoresis based on the use of an internal standard (compound of similar nature and acidity constant as the analyte) has been developed. This method requires only two electrophoretic runs for the determination of an acidity constant: a first one at a pH where both analyte and internal standard are totally ionized, and a second one at another pH where both are partially ionized. Furthermore, the method is not pH dependent, so an accurate measure of the pH of the buffer solutions is not needed. The acidity constants of several phenols and amines have been measured using internal standards of known pK_a, obtaining a mean deviation of 0.05 pH units compared to the literature values.     

Binding of nontarget microorganisms from food washes to anti-<Emphasis Type="Italic">Salmonella</Emphasis> and anti-<Emphasis Type="Italic">E. coli</Emphasis> O157 immunomagnetic beads: most probable composition of background Eubacteria

We present herein the composition of bacterial communities occurring in ground chicken and the changes which arise in these populations based upon nonselective partitioning by commercially-available Dynal anti-Salmonella and anti-E. coli O157 immunomagnetic beads (IMB). Our enumeration and colony selection protocol was based upon a 6 × 6 drop plate method (n = 18 for each 25-g sub-sampling) using a dilution which resulted in ca. 4–8 colonies per drop. An average of 82 ± 13 colonies were selected from three 25-g ground chicken subsamplings per batch, each of which was repeated seasonally for one year. DNA was extracted from each colony and the composition of Eubacteria in each of these harvests was determined by sequence-based identification of 16S rDNA amplicons. The Gram-positive bacteria Brochothrix thermosphacta and Carnobacterium maltaromticum were the most commonly found organisms in both the total chicken wash (PBS) and in the IMB-bound (PBS-washed) fractions. The remaining background organisms which also adhered to varying degrees to commercial IMBs were: Pseudomonas oleovorans, Acinetobacter lwoffi, Serratia spp., and one Rahnella spp. A large number of the organisms were also cladistically evaluated based on rDNA basepair disparities: all Brochothrices were monophyletic; twelve different Pseudomonads were found along with eight Carnobacteria, seven Acinetobacteres, four Serratiae, and two Rahnellae. Carnobacterium alone showed an IMB-based concentration enhancement (ca. two to sixfold). Any reference to a brand or firm name does not constitute endorsement of the US Department of Agriculture over others of a similar nature not mentioned     

Fourier transform infrared spectrum, vibrational analysis and structural determinations of the trans-bis(glycine)nickel(II) complex by means of the RHF/6-311G and DFT:B3LYP/6-31G and 6-311G methods

The trans-bis(glycine)nickel(II) complex was synthesized, and the Fourier transform infrared spectra in the regions 4000-370 cm(-1) and 700-30 cm(-1) were measured. Band deconvolution analysis and the second derivative of the infrared spectrum were also performed. The determination of the geometrical structure in the trans position of the glycine ligands around Ni(II) for the trans-bis(glycine)nickel(II) complex as well as the vibrational assignment were assisted by RHF/6-311G and by Density Functional Theory calculations, DFT:B3LYP/6-31G and 6-311G basis sets. A full discussion of the framework vibrational modes was done using as criteria the geometry study of distorted structures generated for the vibrational modes. Incidentally, Normal Coordinate Analysis was carried out for the Ni(N)(2)(O)(2) structural fragment. The calculated DFT spectra in the high- and low-energy regions agree with the observed ones.