Preparation and crystal structure of hydrated crystalline complex of ciprofloxacin and copper tetrachloride

Synthesis of a complex formed by ciprofloxacin (cfH) and copper(II) chloride is described; its crystal structure is reported and analyzed in comparison to related compounds. The obtained compound (cfH₃)CuCl₄·H₂O (cfH ₃ ²⁺ — double protonated cfH molecule) crystallizes as platelets of P2₁/c symmetry having the unit cell parameters a = 13.491(1) Å, b = 11.0459(7) Å, c = 16.299(1) Å; β = 111.392(7)°. Carbonyl oxygen O(1) is protonated, and hydrogen atom combined with it forms an intramolecular hydrogen bond with carboxylic O(2) oxygen (O(1)?O(2) = 2.642(5) Å). Terminal nitrogen atom N(3) of the piperazinyl group is also protonated, and two its hydrogen atoms participate in hydrogen bonds of N-H?Cl type. The structure also has hydrogen bonds O-H?O, O-H?Cl with the participation of water molecules which occupy hydrophilic channels. Molecular ions cfH ₃ ²⁺ make couples with intrapair π?π interactions.     

High performance liquid chromatographic separation of dipeptide and tripeptide enantiomers using a chiral crown ether stationary phase

A chiral stationary phase (CSP) based on (-)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was evaluated for the direct resolution of the enantiomers of dipeptides and tripeptides. The type and concentration of the acid and the methanol content were optimized with regard to retention time and resolution using Ala-Phe as model peptide. A mobile phase consisting of 10 mM sulfuric acid in 70% aqueous methanol was applied to the separation of a set of 16 structurally diverse dipeptides and tripeptides. Generally, the configuration of the amino acid at the N-terminus determined the enantiomer elution order. With a few exceptions the LL- and LD-enantiomers interacted stronger with the CSP compared to the corresponding DD- or DL-enantiomers. The experimental conditions also allowed the simultaneous separation of all four stereoisomers of Ala-Phe. Addition of ammonium sulfate generally reduced retention times and enantiomer resolution. Addition of triethylamine as modifier led to an overall increase of the retention times while the resolution did not show a general trend, increasing in the case of Ala-Ala but decreasing in the case of Ala-Phe.     

Novel alginate-poly(L-histidine) microcapsules as drug carriers: in vitro protein release and short term stability

Spherical, smooth-surfaced and mechanically stable alginate-poly(L-histidine) (PLHis) microcapsules with narrow particle size distributions were prepared by incubating calcium alginate beads in aqueous solutions of PLHis. The in vitro release characteristics, drug loading and encapsulation efficiency of the microcapsules were investigated using bovine erythrocytes hemoglobin (Hb) as a model drug. The results showed that the concentration of Ca(2+) ions had a considerable effect on the drug loading, encapsulation efficiency and in vitro release behavior of the microcapsules. When the concentration of CaCl(2) in the PLHis solution was increased from 0 to 3.0% (w/v), the drug loading and encapsulation efficiency decreased significantly from 38.0 to 4.3% and from 92.9 to 8.0%, respectively, while the total cumulative release of Hb from microcapsules in phosphate buffered saline solution (PBS, pH 6.8) decreased from 96.2 to 72.8% in 24 h. No significant protein release was observed during 70 h of incubation in hydrochloric acid solution (pH 1.2). However, under neutral conditions (PBS, pH 6.8), the Hb was completely and stably released within 24-70 h. An explosion test showed that the stability of alginate-PLHis microcapsules depended strongly on the concentration of PLHis and the calcium ions in solution. [Diagram: see text] Microscopy photo of Hb-loaded alginate-PLHis microcapsules.     

Monte‐Carlo simulation of spatial distribution of characteristic x‐rays in multi‐film targets: source size of Al Kα x‐rays in W/Al film targets

A Monte‐Carlo simulation approach has been applied to describe the spatial distribution of characteristic x‐rays in W/Al film targets of different combinations of film thicknesses for the optimal design of a small‐sized x‐ray source having a high x‐ray intensity. The result has led to optimal combinations of W and Al film targets for 100 kV electrons, e.g. W(1 µm)/Al(20 µm), W(3 µm)/Al(15 µm) and W(5 µm)/Al(8 µm). These Al/W targets could be used as x‐ray sources for a medical instrument currently under development. Copyright © 2004 John Wiley & Sons, Ltd.     

Intermolecular hydrogen bonds: Comparison of associates in crystals and liquids

The density and sound velocity were measured within wide ranges of temperature for a number of liquids (water, formamide, diols, aliphatic alcohols, cellosolves, ketones), in which various types of H-associate can exist. The temperature dependences of the adiabatic and molar adiabatic compressibility, density, and molar volume are analyzed. The values of the molar adiabatic compressibility permit one to evaluate the dimensionality of H-associates existing in liquids; the values of adiabatic compressibility do not offer this possibility. The terms responsible for the similarity and difference between H-associates in crystals and liquids are discussed.     

Silica-supported Copper（Ⅱ） Catalyzed Coupling of Arylboronic Acids with Imidazoles

Immobilized copper（Ⅱ） in organic-inorganic hybrid materials catalyzed Ar-N coupling of arylboronic acids with imidazoles has been developed. Arylboronic acids reacted with imidazoles smoothly in the presence of a 3-（2-aminoethylamino）propyl functionalized silica gel immobilized copper（Ⅱ） catalyst （10 mol%） in methanol without any additives and bases. The reactions generated the corresponding cross-coupling products in good yields. Furthermore, silica-supported copper can be recovered and recycled by a simple filtration procedure and used for five consecutive trials without decreases in activity.     

“逐步偶联聚合反应”在研制有序交联高分子及复合物中的应用

用“逐步偶联聚合反应”这一新的合成方法可制备不同等级的微观结构可控的有序交联网状高分子,包括可溶性的一维梯形或管状高分子、不溶性的二维或三维筛板状高分子,新型的反应性梯形聚硅氧烷包括氢梯、乙烯基或丙烯基梯、乙氧基梯及其共聚物是功能性梯形高分子的前体,由此衍生出“鱼骨形”和“划艇形”液晶和非线性高分子、盘状金属络合物液晶高分子以及管状聚硅氧烷。对功能化梯形降硅氧烷进行了有趣的应用探索,包括用于稳定液     

Synthesis and structure of tetraphenylantimony hydrogen phthalate

Tetraphenylantimony hydrogen phthalate, Ph4SbOC(O)C6H4000H-o, was prepared by the reaction of pentaphenylantimony with phthalic acid. According to the data of X-ray structural analysis, the resulting compound is a trigonal-bipyramidal complex of antimony with three phenyl groups in equatorial positions; the fourth phenyl group and the carboxyl fragment are in axial positions. The CSbO angle is 177.5(1)° the Sb-C(Ph)_eq and Sb-C(Ph)ax distances are 2.099(4)-2.177(4) A and 2.129(4) A, respectively. The H atom of the free carboxyl group and the carbonyl O atom of another carboxylate group form an intramolecular hydrogen bond.DeceasedTranslated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2082–2085, August, 1996.     

Controllable and flexible cellular network for virus cell-to-cell spread

Cellular networks were constructed based on PEG modification and soft lithography, in which cell numbers and spatial distributions can be controlled. A micro-injector was combined with cellular networks to fix virus induced plaque and virus spread direction, by which virus cell-to-cell spread can be distinguished from cell-free spread.     

Solvent and substituent effects on the conformational equilibria and intramolecular hydrogen bonding of 4-substituted-2-hydroxybenzaldehydes

By applying the B3LYP/6-31G(d) method with the SCIPCM model on seven 4X substituted 2-hydroxybenzaldehydes, some structural characteristics related with their conformational equilibria and intramolecular hydrogen bonds have been clarified. The compounds are almost completely under the planar conformation characterized by a strong intramolecular hydrogen bond, which decreases in those solvents that possess a higher hydrogen bond donating capability and polarity. The substituents exert a marked influence on the conformational equilibrium constants and the strength of the IHB. Moreover, the excellent Hammett-type equations obtained support the proposed conformational reactions to quantify the IHB in the o-hydroxybenzaldehydes studied.