Complexes of barium ions with quercetin-5′-sulfonic acid and sodium salt of morin-5′-sulfonic acid

Complex formation of Ba²⁺ ions with quercetin-5′-sulfonic acid and sodium salt of morin-5′-sulfonic acid was studied by potentiomety. Solid complexes were obtained, and their composition and physicochemical properties were studied.     

Two polymerizable derivatives of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)

[structure: see text] A versatile strategy for the synthesis of polymerizable derivatives of the redox-active indicator dye 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) is reported. Two products are shown to illustrate how the final step in the synthetic strategy can be used to alter the physical properties of the product. Both products were characterized spectroscopically and electrochemically. The hydrophilic monomer (sABTS) was polymerized, and the utility of this polymer (polyABTS) is demonstrated in the context of bioelectrocatalysis.     

Complex formation and Fluorescence : Complexes of 8-hydroxyquinoline-5-sulfonic acid

The fluorescence of solutions of cation complexes with 8-hydroxyquinoline-5-sulfonic acid has been studied. The complexes formed with transition elements do not fluoresce. The additivity of the fluorescence at certain pH values has been used to indicate new generally applicable analytical method for mixtures of cations which have similar reactions. The method is especially applicable to small or very dilute samples.     

Application of 8-hydroxyquinoline-5-sulfonic acid in the spectrophotometric determination of some lanthanides

A simple, sensitive, and selective spectrophotometric method for the determination of trivalent praseodymium, neodymium, samarium, gadolinium, dysprosium, and erbium ions with 8-hydroxyquinoline-5-sulfonic acid is described. The optimum conditions for determination of down to 10.0 μg/ml of lanthanide ion are reported. The proposed method shows an average recovery of 99.9% with standard deviation not exceeding 0.1%. The metal-ligand ratio and stability constant of the chelates are determined.     

Enhancement and quenching of fluorescence of metal chelates of 8-hydroxyquinoline-5-sulfonic acid

Fluorescence enhancement of 8-hydroxyquinoline-5-sulfonic acid complexes of Mg, Ca, Sr, Ba, Al, Zn and Cd were studied in micellar and hydroorganic solvents. Al is extraordinarily amenable to both types of fluorescence enhancement, an order of magnitude to two order of magnitude enhancement of fluorescence intensity has been observed with aqueous hexadecyltrimethylammonium chloride (HTAC) and certain mixed aqueous-organic solvents. Fe(III) appears to be an unusually powerful fluorescence quencher in these systems — the effect is noticeable in low micromolar concentrations and is greatly amplified by cationic surfactants such as HTAC.     

Flow-injection spectrophotometry of manganese by catalysis of the periodate oxidation of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)

A sensitive flow-injection spectrophotometric procedure is proposed for the determination of manganese(II), based on its catalytic effect on the oxidation of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with periodate. By monitoring the change in absorbance of the oxidation product of ABTS at 415 nm, manganese(II) in the range 0.05–1.0 ng ml⁻¹ can be determined with a sampling frequency of 30 h⁻¹. A relative standard deviation (R.S.D.) (n=10) is 1.6% at the 0.5 ng ml⁻¹ level. The proposed method suffers from few interferences and has been successfully applied to the determination of manganese in river, lake and seashore water samples.     

Photophysical and photochemical studies of 2-phenylbenzimidazole and UVB sunscreen 2-phenylbenzimidazole-5-sulfonic acid

The sunscreen agent 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and its parent 2-phenylbenzimidazole (PBI) cause DNA photodamage via both Type-I and Type-II mechanisms when UVB irradiated. We have studied the photophysical and photochemical properties of these compounds and their ability to photogenerate reactive oxygen species including free radicals. PBI and PBSA exhibit both oxidizing and reducing properties in their excited state. The absorption and fluorescence properties of PBSA depend strongly upon pH, and hence the photochemistry of PBSA was studied in both neutral and alkaline solutions. PBSA showed strong oxidizing properties when UV irradiated in neutral aqueous solution (pH 7.4) in the presence of cysteine, glutathione and azide, as evidenced by the detection of the corresponding S-cysteinyl, glutathiyl and azidyl radicals with the aid of the spin trap, 5,5-dimethyl-1-pyrroline N-oxide (DMPO). However, when an aqueous anaerobic solution (pH 10) of PBSA and either nitromethane (NM) or 4-nitrobenzoic acid (4-NBA) were irradiated, the corresponding nitro anion radicals were observed. This finding suggests that both NM and 4-NBA are reduced by direct electron transfer from the excited state PBSA. During UV irradiation of an aerobic solution of PBSA, O2*- and *OH radical were generated and trapped by DMPO. Further, PBI (in ethanol) and PBSA (in ethylene glycol : water 2: 1 mixture) showed low temperature (77 K) phosphorescence (lambdamax = 443, 476 and 509 nm) and also an electron paramagnetic resonance half-field transition (deltaMs = +/-2), which is evidence for a triplet state. This triplet produced singlet oxygen (1O2) with quantum yields 0.07 and 0.04 in MeCN for PBI and PBSA, respectively. These studies demonstrate that UV irradiation of PBSA and PBI generates a variety of free radicals and active oxygen species that may be involved in the photodamage of DNA.     

两个基于2,2′-联吡啶-3,3′-二羧酸的稀土配合物的晶体结构和荧光性质(英文)

采用水热法合成了2个具有二维结构的吡啶羧酸类稀土配位聚合物{[Ln2(bpdc)3(H2O)2]·5H2O}n,(Ln=Nd(1),Eu(2);bpdc=2,2′-Bipyridyl-3,3′-dicarboxylic acid)。单晶衍射分析显示1、2结构相似,均属于单斜晶系,P2/c空间群。1、2的晶胞参数分别为a=1.241 00(19)nm,b=0.748 35(59)nm,c=2.060 50(20)nm,β=94.84(1)°;a=1.241 00(19)nm,b=0.743 01(20)nm,c=2.052 50(30)nm,β=94.95(2)°。配合物是由之字形一维链构成的二维网络结构,其拓扑符号为{3^9;4^18;5}。热重测试结果表明1、2热稳定性较好。配合物2显示出很好的荧光性能。     

The reaction between palladium(II) and complexes of 8-quinolinol-5-sulfonic acid

Anomalous results for the reaction between palladium(II) and fluorescent complexes of 8-quinolinol-5-sulfonic acid were found to be due to a slow reaction. Heating the solution permits the determination of palladium(II) in combination with copper(II) or nickel(II), the two cations being titrated stepwise The approximate value for the overall formation constant of the PdL₂^2- complex was determined.     

Chemical and photoluminescence properties of purified poly(2-methoxyaniline-5-sulfonic acid) and oligomer

Both the chemical and the electrochemical synthesis of poly(2-methoxyaniline-5-sulfonate) (PMAS) in aqueous media have been found to give two distinct polymer fractions with molecular weights of approximately 8-10 and 2 kDa, respectively. It is now possible to isolate the pure high molecular weight (HMWT) PMAS and low molecular weight (LMWT) PMAS oligomer and to study their individual and combined photochemistry and redox chemistry. The HMWT PMAS fraction was confirmed to be an emeraldine salt by its characteristic redox and pH switching behavior, in contrast to the oligomeric LMWT PMAS, which was inert under the same conditions. Mixtures of these two fractions exhibit photoluminescence arising from the oligomeric LMWT PMAS fraction. The observed LMWT PMAS emission was modulated by the presence of the conducting HMWT PMAS emeraldine salt via a static resonant energy transfer arising from quenching at 460 nm when excited at 355 nm. The nonlinear fluorophore-quencher behavior suggests that the two PMAS fractions are strongly associated. The behavior fitted the static Perrin quenching model in which the oligomeric LMWT PMAS fluorophore is diffusionally restricted by the presence of HMWT PMAS quencher.     

Fluorimetric sequential injection determination of magnesium using 8-hydroxiquinoline-5-sulfonic acid in a micellar medium

A fluorimetric sequential injection method for the determination of magnesium is proposed. The system is based on the complex formation between Mg(II) and 8-hydroxyquinoline-5-sulfonic acid (HQS). The reaction was carried out in the presence of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) as a masking agent. Cetyltrimethylammonium chloride (HTAC) was employed as a fluorescence enhancer. The influence of several variables, such as reagent concentration, volumes and pH has been investigated. The reagent was prepared in a 0.1 M Tris-HCl buffer solution (pH 9). A detection limit of 12 mug l(-1) magnesium was obtained. The proposed method was applied to the determination of magnesium in natural waters.     

Substitution reactions of 5-nitropyridine-2-sulfonic acid. A new pathway to 2,5-disubstituted pyridines

We have investigated reactions of 5-nitropyridine-2-sulfonic acid and its potassium salt in which substitution of the sulfonate group by oxygen, nitrogen and halogen nucleophiles has been attempted. By this approach, 2-methoxy- (95% yield), 2-ethoxy- (97%), 2-isopropoxy- (65%), 2-amino- (92%), 2-butylamino- (76%), 2-diethylamino- (62%), 2-ethylamino- (32%), 2-benzylamino- (77%), 2-(R-1-phenylethylamino)- (71%) and 2-chloro-5-nitropyridine (87%) have been obtained. No reactions were observed with phenols or anilines. With t-BuOH, 2-hydroxy-5-nitropyridine was formed together with 2-methylpropene.     

Synthesis,crystal structure and properties of inorganic-organic hybrid polymers based on 8-hydroxylquinoline-5-sulfonic acid

Two new inorganic-organic hybrid polymers, Mn(QS)(H2O) (1) and Co(QS)(H2O)2 (2) (H2QS=8-hydroxyl-quinoline-5-sulfonic acid), based on 8-hydroxylquinoline-5-sulfonate ligand, have been synthesized under solvothermal conditions and their structures were solved by single-crystal X-ray diffraction analysis. Compound 1 is a three-dimensional open framework with rutile topology structure, and compound 2 is a three-dimensional supramolecular structure. These compounds were characterized by powder XRD, infrared spe...     

8-羟基喹啉-5-磺酸构筑的有机-无机配位化合物的合成、结构和性质研究

在溶剂热条件下,以8-羟基喹啉-5-磺酸为配体,合成了两个新的有机-无机配位化合物Mn（QS）（H2O）（1）和Co（QS）（H2O）2（2）（H2QS=8-hydroxylquinoline-5-sulfonic acid）,并且对他们进行了单晶X-射线解析.其中化合物1是一个具有金红石拓扑的三维开放骨架结构,化合物2是一个三维超分子结构.我们对这些化合物进行了粉末X射线,红外光谱,差热热重,荧光光谱和磁学性质的研究.