Complexes self‐associate by hydrogen bonding and metallophilic attraction: Theoretical study

Hydrogen bonding and metallophilic attractions are studied in the model systems: [(AuNH₃Cl)₂], [(AuNH(CH₃)₂Cl)₂], [{Au₂(μ‐SH)(PH₂O)(PH₂OH)}₂], [(CuNH₃Cl)₂], and [{Cu(NH₃)Cl}₄] at the Hartree–Fock (HF) and second‐order Møller–Plesset (MP2) levels. The two interactions are found to be comparable and prevailing in the final structure. It is determined that the aurophilic contact has a same magnitude that the hydrogen bonding, and is stronger than the cuprophilic interaction. The presence of hydrogen bond directs the growth of the crystal. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Crystal Structures and Magnetic Studies of Naphthalene Derivatives Containing Nitronly Nitroxides

Crystal structures of new nitronyl nitroxide derivatives 1, 2 and 3 were determined with X‐ray diffraction analysis: 1, monoclinic, C₂/c, a = 1.2404(5) nm, b = 0.9730(5) um, c = 2.7049(10) ran, β = 98.189(15)°, V = 3.2315(24) nm³, Z = 8; 2, or‐thorhombic, Pbca, a = 0.61262(2) nm, b = 1.11426(6) nm, c = 2.30543(13) nm, V = 1.57373(13) nm³, Z = 4; 3, monoclinic, P2(1)/n, a=0.64253(4) nm, b=2.55003(17) nm, c = 1.15497(6) nm, β = 95.000(3)°, V = 1.8852(2) nm³, Z = 4. Their magnetic properties were measured with SQUID and analyzed based on their crystal structures with simple singlet‐triplet, modified one dimensional antiferromagnetic chain and modified singlet‐triplet models respectively: 1, J/k_b= ?2.5 K; 2, J/k_b = 7.8 K, θ = 2.8 K; 3, J/k_b = ?0.96 K, θ = 0.21 K.     

Die Kristallstruktur von wasserfreiem Melaminiumchlorid

Crystal Structure of non‐aqueous Melaminium Chloride Melaminium chloride was obtained as colorless, needle‐shaped, single crystalline material from solid state reactions between melamin and ammonium chloride. The structure of [C₃N₆H₇]Cl was refined by single crystal X‐ray diffraction: I2/m, Z = 8, a = 852.87(4), b = 1704.4(1) c = 918.44(4) pm and β = 92.165(6)°. The crystal structure contains melaminium ions stacked to columns along [100] and linked via N‐H···N bridges to form bands along [001]. Both of the two distinct chloride ions are stabilized by six hydrogen bonds through distorted trigonal prismatic arrangements of hydrogen atoms to yield a supramolecular structure.     

Theoretical study of p‐methacryloyl‐aminophenylarsonic acid

Conformations of p‐methacryloylaminophenylarsonic acid (p‐MAPHA) are determined through molecular mechanics and DFT/B3LYP calculations. Solvation effects are studied within the self‐consistent isodensity continuum model (SCI‐PCM). The stationary points were found to correspond to minima as verified by the analysis of vibrational frequencies in the molecule. The molecular optical absorption was obtained by using different solvent environments. The present results are in good agreement with the available experimental data. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Simple synthesis of aminoquinoline/ethylaniline copolymer semiconducting nanoparticles

Pure copolymer nanoparticles from 8-aminoquinoline (AQ) and 2-ethylaniline (EA) were easily synthesized by a chemically oxidative polymerization in three different aqueous media. The potential and temperature of polymerization solution were used to successfully follow the polymerization progress. The molecular and morphological structures of the resulting AQ/EA copolymer particles were systematically characterized by IR, UV/Vis, NMR, gel permeation chromatography, laser particle-size analysis, atomic force and transmission electron microscopy. The oxidation potential of the monomers as well as the polymerization yield, structure, and properties of the particles were found to significantly depend on AQ/EA ratio, polymerization temperature and medium. It is surprisingly found that AQ homopolymerization and AQ/EA (50:50) copolymerization at 5 degrees C in HCl simply afford nano-ellipsoids with the major/minor axis diameters of 24/14 nm and 80/67 nm, respectively. A simple method of synthesizing semiconducting pure nanoparticles by introducing the AQ units with positively charged quaternary ammonium groups but in the absence of adscititious stabilizer or sulfonic substituent on the monomers is established first. Both the molecular weight and bulk electroconductivity of the copolymers exhibit a maximum at AQ content of 10 mol %. The solubility and film formability of the copolymers are good in highly polar solvents and reach the optimal at the AQ content of 20 and 10 mol %, respectively.     

Study on the Interaction between Gatifloxacin Mesylate and Salmon Sperm DNA by Fluorescence Method

The interaction between gatifloxacin mesylate (GM) and salmon sperm DNA was studied by fluorescence spectrometry and ultra‐violet (UV) spectrometry. Additions of salmon sperm DNA to GM solution resulted in its strong fluorescence quenching and UV absorbance decrease due to the strong interaction between GM and salmon sperm DNA. Both the maximum fluorescence emission wavelength and the maximum UV absorbance wavelength of GM did not change with the increasing concentration of salmon sperm DNA, indicating no intercalative binding existed between them. The Stern‐Volmer plot indicated that the fluorescence‐quenching constant at different temperatures or different salmon sperm DNA concentration ranges was different. Effects of ionic strength and I^? on the fluorescence quenching of GM by salmon sperm DNA indicated that electrostatic interaction and groove binding coexisted between them.     

Electrochemical Preparation of Poly(Malachite Green) Film Modified Nafion‐Coated Glassy Carbon Electrode and Its Electrocatalytic Behavior Towards NADH,Dopamine and Ascorbic Acid

Poly(malachite green) film modified Nafion‐coated glassy carbon electrodes have been prepared by potentiodynamic cycling in malachite green solution. The pH of polymerisation solution has only minor effect on film formation. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the growth of the poly(malachite green) film. Cyclic voltammogram of the poly(malachite green) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 56 mV per pH unit. The electrocatalytic behavior of poly(malachite green) film modified Nafion‐coated glassy carbon electrodes was tested towards oxidation of NADH, dopamine, and ascorbic acid. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(malachite green) film compared to bare glassy carbon electrode. In the case of NADH, the overpotential was reduced substantially on modified electrode. Finally, the feasibility of utilizing poly(malachite green) film electrode in analytical estimation of ascorbic acid was demonstrated in flow injection analysis.     

Synthesis of 4(3H)-Quinazolinone Derivatives and Their in vitro Antitumor Activity

Classical antifolates containing L-glutamic acid moiety in molecule have shortcomings such as drug resistance which is originated from the defective cell transport by mutation, and toxicity to the host which is due to unnecessarily long retention inside normal cells.[1] One strategy to overcome these shortcomings is to design nonclassical lipophilic inhibitors of folate requiring enzymes by deleting or modifying L-glutamic acid component from the folate analogues.     

流动分析法同时测定铬（Ⅵ）及铬（Ⅲ）过程中铈（Ⅳ）氧化剂的影响

以Ｃｅ（Ⅳ）为氧化剂，采用流动分析在线氧化技术，实现了对Ｃｒ（Ⅵ）和Ｃｒ（Ⅲ）的同时在线分析，发现Ｃｅ（Ⅳ）氧化剂在测定过程中产生负干扰，在而Ｃｒ（Ⅲ）存在时会使Ｃｒ（Ⅵ）的测定结果偏高，本文提出了一个校正模型，通过数学方法消除上述干扰，所建立的分析方法对Ｃｒ（Ⅵ）和Ｃｒ（Ⅲ）分析的平均相对误差不大于６．５％。     

Tetraazadibora[3, 3]paracyclophane

Starting from the para‐phenylenediamine derivative HN(SiMe₃)‐C₆H₄‐NH(SiMe₃), a lithiation and subsequent borylation give [(MeO)₂B]N(SiMe₃)‐C₆H₄‐N(SiMe₃)[B(OMe)₂] ( 1 ), the hydridation of which yields Li₂[(H₃B)N(SiMe₃)‐C₆H₄‐N(SiMe₃)(BH₃)] ( 2 ). Applying ZrCl₄ upon 2 initiates a condensation to give the title compound [‐N(SiMe₃)‐p‐C₆H₄‐N(SiMe₃)‐BH‐]₂, a hetero[3, 3]paracyclophane with two N‐B‐N chains that connect the para‐phenylene units. The product 3 crystallizes in the orthorhombic space group P2₁2₁2₁.