荷移荧光光谱法测定加替沙星

研究了加替沙星(GFLX) 与电子受体四氯对苯醌(TCBQ)之间的荷移反应,建立了测定加替沙星的新方法。实验结果表明,在甲醇-水介质中于45 ℃水浴恒温20 min,GFLX与TCBQ可形成稳定的1∶1电荷转移络合物,其荧光发射强度较GFLX本身有显著的增强。在0.19～5.6 mg·L-1 浓度范围内,荧光强度与GFLX浓度呈良好的线性关系,检出限为0.005 6 mg·L-1。用于药物制剂中GFLX的含量测定,其回收率为101.1%～103.9%;标准偏差为1.0%～1.9%。同时建立了测定尿样中GFLX的荷移同步荧光光谱法,GFLX浓度在0.023～3.4 mg·L-1范围内与荧光强度呈良好的线性关系,检出限为0.003 4 mg·L-1。用本方法测定尿液中的GFLX,结果与文献值基本一致,回收率为93.9%～101.0%;标准偏差为1.0 %～1.7%。     

Water-promoted unprecedented chemoselective nucleophilic substitution reactions of 1,4-quinones with oxygen nucleophiles in aqueous micelles

Unique nucleophilic substitution and addition reactions of nitrogen and sulfur nucleophiles with 1,4-quinones in aqueous suspension with amines and thiols have recently been demonstrated by us.² However, the reactivity of oxygen nucleophiles toward nucleophilic substitution compared to nitrogen and sulfur nucleophiles ‘on water’ is not facile. An unprecedented economical, green methodology approach using ordinary laundry detergent (LD; washing powder, 0.5 mol %, reusable)/SDS as surfactant ‘in water’ for nucleophilic substitution by oxygen nucleophiles in 1,4-quinones in excellent yields has been demonstrated.     

Using Capsaicin Modified Multiwalled Carbon Nanotube Based Electrodes and p‐Chloranil Modified Carbon Paste Electrodes for the Determination of Amines: Application to Benzocaine and Lidocaine

The utilization of the capsaicin modified carbon nanotube modified basal‐plane pyrolytic graphite electrode or p‐chloranil modified carbon paste electrodes are presented for the determination of pharmaceutical compounds containing amine functionality, such as benzocaine and lidocaine. In detection of benzocaine at a capsaicin modified electrode, the guaiacol functional group is irreversibly electrochemically oxidized to form the o‐quinone derivative which then undergoes nucleophilic attack by the aromatic amine group in benzocaine via a 1,4‐Michael addition mechanism forming a catechol‐amine adduct. The electrochemically initiated formation of the capsaicin‐benzocaine adduct causes a linear decrease in the voltammetric signal corresponding to capsaicin which correlates to the added concentration of benzocaine.     

Conductimetric Studies of Charge Transfer Complexes of p‐Chloranil with Some Alicyclic Amines in Polar Media

The stoichiometry of charge‐transfer complexes which ionise in polar media has been studied by conductimetric titration technique in the systems morpholine‐p‐chloranil (CA), piperidine‐CA and pyrrolidine‐CA in three different polar solvents namely N,N‐dimethylformamide, acetonitrile and dimethylsulfoxide at different temperatures of 10, 15, 18, 20, 25 and 30 °C. The stoichiometric ratios of these complexes were found to vary from 1:1 to 1:4 (acceptor: donor) depending on the system, temperature and solvent used. The ασ_M‐values of these complexes have been reported. The effect of solvents, temperatures and types of electron donors on the σ_P‐values has been examined.     

Synthesis and spectroscopic studies of the charge transfer complexes of 2- and 3-aminopyridine

The interactions of the electron donors 2-aminopyridine (2APY) and 3-aminopyridine (3APY) with the π-acceptors tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 2-chloro-1,3,5-trinitrobenzene (picryl chloride, PC), and 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) were studied spectrophotometrically in chloroform at room temperature. The electronic and infrared spectra of the formed molecular charge transfer (CT) complexes were recorded. Photometric titration showed that the stoichiometries of the reactions were fixed and depended on the nature of both the donor and the acceptor. The molecular structures of the CT-complexes were, however, independent of the position of the amino group on the pyridine ring and were formulated as [(APY)(TCNE)], [(APY)(DDQ)], [(APY)(PC)], and [(APY) (chloranil)]. The formation constants (K_CT), charge transfer energy (E_CT) and molar extinction coefficients (_CT) of the formed CT-complexes were obtained.     

分光光度法研究氨基酸与四氯苯醌形成的荷移配合物

本文用分光光度法研究了5种氨基酸与四氯苯醌形成的荷移配合物.通过对影响配合物形成因素的研究,确立了以四氯苯醌形成荷移配合物的方法测定氨基酸的最佳反应条件,测定了反应平衡常数.讨论了配合物的组成.     

Mechanistic study of the oxidation of -ascorbic acid by chloranil at the nitrobenzene water interface

The redox reaction between -ascorbic acid in water and chloranil in nitrobenzene has been studied by means of polarography with an ascending water electrode as well as cyclic voltammetry with a stationary interface. Through accurate measurement of the limiting currents, it has been suggested that the redox reaction should be a two-electron reaction rather than a one-electron reaction described previously. A spectrophotometric technique has also been used to observe that the redox reaction proceeds spontaneously under certain conditions even without electrochemical control. Based on these findings, it has been concluded that the present heterogeneous charge transfer reaction is the ion transfer of chloranil semiquinone radical, which is driven by the homogeneous electron transfer between ascorbic acid and chloranil in the aqueous phase.     

Synthesis, characterization and spectroscopic investigation of pyrazinoporphyrazine network polymer-supported metal (II)-based catalysts

Chloranil through condensation reaction with vicinal diamine such as diaminomaleonitrile produced heterocyclic monomer, p-benzoquinonebis[2,3-b; 2′,3′-b′]pyrazine-5,6-dinitrile. The tetranitrile monomer was cyclo-tetramerised using lithium/pentanol and acetic acid affording the corresponding tetra p-benzoquinone bis[2,3-b; 2′,3′-b′]pyrazinoporphyrazine)]-based network polymer (2H-Pz). The tetranitril monomer was cyclo-tetramerised using metal salt and quinoline affording the corresponding porphyrazinato-metal II-based network polymers (M-Pz), M = Co, Ni or Cu. Elemental analytical results, IR and NMR spectral data of the prepared molecules are consistent with their assigned formulations. Molecular masses and metal contents of the synthesized polymers proved to be of high molecular masses which confirm the efficiency of tetramerization polymerization and complexation reactions. The prepared pyrazinoporphyrazines were used as efficient catalysts for the oxidation of thiophenol and benzylthiol to their disulfides in the presence of air atmosphere. The results of oxidation of thiophenol and benzylthiol show that after 15 min the maximum yield of the corresponding disulfides reached 95%, 91%, respectively.     

表面活性剂增敏荷移反应紫外分光光度法测定三聚氰胺

在pH =7.55的Tris-HC1缓冲溶液中,以十六烷基三甲基溴化铵( CTMAB)为增敏剂,三聚氰胺与四氯对苯醌之间发生荷移反应,研究了其反应产物的紫外光谱性质,据此建立了荷移反应紫外分光光度法测定三聚氰胺的方法.三聚氰胺的线性范围为8.61×10-8 ～2.60×10 -6mol/L,r=0.9995,检出限为2...