三维Cu-MOF对亚甲蓝的吸附和光催化降解及其机理

本文报道了[Cu₃(ppda)₃(tib)₂(H₂O)₄]·6H₂O (Cu-MOF)的合成、结构、吸附和光催化降解性能。在Cu-MOF中，1，4-苯二乙酸(H₂ppda)和1，3，5-三(1-咪唑基)苯(tib)配体交替连接Cu离子形成二维层，层与层之间通过trans-ppda^2-相互穿插形成稳定的三维结构。Cu-MOF对亚甲蓝(MB)的催化效率为97%，最高反应速率常数为0.019 7 min^-1。光催化降解机理：在光的激发下，催化剂表面的光生电子和空穴对发生分离，并与O₂、H₂O、H₂O₂反应生成活性物质，将染料降解为CO₂和H₂O。在MB溶液中加入NaCl (200 g·L^-1)后，Cu-MOF的吸附量有所提升(87.23 mg·g^-1)，准二级动力学模型和Langmuir等温线模型的实验数据拟合程度较好，该吸附的主要过程为单层化学吸附。     

Grafted Azure A modified electrodes as disposable β-nicotinamide adenine dinucleotide sensors

We report the in situ generation of aryl diazonium cations of Azure A, a redox-active phenothiazine dye, by reaction between the corresponding aromatic aminophenyl group and sodium nitrite in 0.1 M HCl. The subsequent electrochemical reduction of these dye diazonium salts gives rise to conductive electrografted films onto screen-printed carbon (SPC) electrodes. The resulting Azure A films have a very stable and reversible electrochemical response and exhibit potent and persistent electrocatalytic behavior toward NADH oxidation. We have optimized the electrografting conditions in order to obtain SPC modified electrodes with high and stable electrocatalytic response. The kinetic of the reaction between the NADH and the redox active centers in the Azure A film has been characterized using cyclic voltammetry and single step chronoamperometry. The catalytic currents were proportional to the concentration of NADH giving rise to linear calibration plots up to a concentration of 0.5 mM with a detection limit of 0.57 ± 0.03 μM and a sensitivity of 9.48 A mol cm⁻² μM⁻¹. The precision of chronoamperometric determinations was found to be 2.3% for five replicate determinations of 3.95 μM NADH. The great stability of such modified electrodes makes them ideal for their application in the development of biosensing platforms based on dehydrogenases.     

Synthesis and Evaluation of Technical Properties of Novel Cationic Mono‐s‐chloro Triazinyl (MCT) Reactive Dyes on Cotton

Two novel cationic mono‐s‐chloro triazinyl (MCT) reactive dyes together with their analogues were synthesized via reacting an N,N‐dimethyl dodecylamine with p‐nitrobenzyl bromide. The resultant was reduced using stannous chloride and hydrochloric acid to produce the primary amine. The quaternary ammonium salt containing primary amine was then diazotized and coupled to H‐acid/J‐acid reacted with cyanuric chloride and sulfanilic acid. The analogue dyes were prepared via the same route without quaternary ammonium salt making stage. The dyes were characterized using FTIR, ¹H NMR, UV‐Vis spectroscopy and elemental analysis. The substantivity, exhaustion and fixation of the dyes were investigated on cotton fabric. It was found that these functional dyes could be effectively introduced to cotton for achieving simultaneous coloration and functional finishing effects. All the dyed fabrics exhibited softening efficacy. The washing and light fastness of the dyed samples were further studied.     

Two Novel Push?Pull Series of Benzothiazole‐Based Dyes: Synthesis and Characterization

New dichromophoric cyanine dyes based on benzothiazol‐2‐amines as push? pull systems were synthesized in two series of disperse and cationic forms (see 4 in Scheme 1 and 5 in Scheme 2, resp.). Their thermal stabilities, UV/VIS, fluorescence, and solvatochromic behavior, which are important parameters in push? pull systems, were also studied.     

Spectroscopic analysis of naphtholazobenzimidazole in organised solution

Micelle–water partition coefficient (K_x ) of naphtholazobenzimidazole dye (NAB) in aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) has been determined spectrophotometerically. Changes in absorption patterns of dye caused by surfactants and solvents were quantified in terms of dye–surfactant ratio (n _D/n _S) and solvent water partition coefficients (P), respectively. Multiple residence sites have been suggested for dye molecules within micelles, based on shifts in azo-hydrazone tautomeric equilibrium. Micelle–water partition coefficients were used to evaluate the influence of dye on critical micelle concentration of CTAB and SDS. At same micelle concentration, M, the relative solubility of NAB was greater in cationic surfactant CTAB than in anionic surfactant SDS.     

Triorganotin(IV) esters of 2-{[ N -(2-oxo-2H-naphthalene-1-yliden)hydrazo]}benzoic acid,instability of the cyclohexyl derivative

Three triorganotin(IV) esters of 2-{[N-(2-oxo-2H-naphthalene-1-yliden)hydrazo]}benzoic acid were prepared and studied by IR and NMR spectroscopy and X-ray crystallography for the tributyl- and triethyltin(IV)-2-{[N-(2-oxo-2H-naphthalene-1-yliden)hydrazo]}benzoates (2, 3). These compounds are monomeric in solution with four-coordinate tin. The hydrazo tautomeric forms are present in chloroform solution as well as in the solid state. The coordination geometries of tin in 2 and 3 are trigonal bipyramidal with all three carbons in equatorial positions, one carboxylic oxygen and the quinone-type oxygen from adjacent molecules are in axial positions forming centrosymmetric dimers with the ring containing 20 members. The yield of the tricyclohexyltin(IV) derivative (4) is much lower than 2 or 3, with instability towards moisture in solution. The product of the reaction with water is the bis(µ²-hydroxo)-bis{2-{[N-(2-oxo-2H-naphthalene-1-yliden)hydrazo]}benzoato}tetracyclohexylditin (4a) dimer. The tin is five-coordinate in the solid state by two cyclohexyl and two hydroxy groups, the last coordination site is occupied by a monodentate carboxy group. The dimeric form of this compound remains in chloroform solution.     

Relationship between dye–iodine binding and cell voltage in dye‐sensitized solar cells: A quantum‐mechanical look

It has been proposed that iodine binding to dyes may actually decrease the cell efficiency of a dye‐sensitized solar cell. A previous experimental study showed that a two‐atom change from oxygen to sulfur increased recombination of iodine with injected electrons by a factor of approximately 2. Here, it is shown that iodine binding is a plausible explanation for this effect. The steric and conjugation effects are quantified separately using a set of model compounds. Quantum‐chemical calculations show that elongation of the hydrocarbon chain has only an insignificant effect on the iodine and bromine binding to the chalcogen atoms (O, S, Se). The conjugation, however, significantly disfavors the iodine and bromine interaction. Iodine and bromine binding to the dye and model compounds containing sulfur is significantly more favorable than to their oxygen containing counterparts. Bromine binding to dyes is shown to be stronger than that of iodine. Accordingly, bromine binding to dyes may contribute significantly to the observed lower efficiencies in cells using Br/Br^? as the redox couple. © 2012 Wiley Periodicals, Inc.