Cu(II) complex of an abiotic receptor as highly selective fluorescent sensor for acetate

A copper complex having quinoline moiety as fluorophore has been synthesized. The anion recognition behavior of the receptor and its copper complex has been studied in acetonitrile and in acetonitrile: H₂O (95:5 v/v). The copper complex shows high selectivity toward acetate over other anions studied such as F⁻, Cl⁻, Br⁻, I⁻, OAc⁻, dl-malate, l-mandelate, benzoate, isophthalate, , and .     

Needle trap extraction for GC analysis of formic and acetic acids in aqueous solution

Formic and acetic acids are ubiquitous in the environment, food, and most of the natural products. Extraction of the acids from aqueous solution is required for their isotope analysis by the gas chromatography-isotope ratio mass spectrometry. To this objective, we have previously developed a purge-and-trap technique using the dynamic solid-phase microextraction technology, the NeedlEX. The extraction efficiency, however, remains unexamined. Here, we address this question using the flame ionization detector and isotope ratio mass spectrometer while comparing it with that of the CAR/PDMS fiber. The results show that the NeedlEX is applicable at a wide range of concentration through coordination of purge volume given the minimum amount 3.7 ng and 1.8 ng of formic and acetic, respectively, is extracted. The efficiency of NeedlEX was 6-7 times lower than the fiber at 1000 μg/mL depending on the analyte. It is, however, superior to the latter at 10 μg/mL or less owing to its lower detection limit. The extraction efficiency of both acids is equivalent in molar amount. This is, however, disguised by the different response of the flame ionization detector. The isotope ratio mass spectrometor overcomes this problem but is compromised by relatively large errors. These results are particularly useful for isotopic analysis of carboxylic acids.     

超声波作用下乙酸辛酯合成条件的研究

在超声波作用下,不用溶剂,以硫酸氢钠为催化剂催化合成乙酸辛酯。最佳反应条件是:正辛醇和乙酸的物质的量比为1∶2.0,催化剂用量为反应物总质量的1.0%,超声时间20min,反应温度84℃。在此反应条件下,酯收率可达80.1%,催化剂可重复使用。     

Different Metal Aggregation in Copper Acetate Chain Coordination Polymers with Dipyridyl Tethers Bearing Hydrogen Bonding Capable Functional Groups

Hydrothermal synthesis has afforded a pair of divalent copper acetate coordination polymers containing either 4, 4′‐dipyridylamine (dpa) or 4‐pyridylisonicotinamide (4‐pina), both of which hydrogen‐bonding capable central functional groups. X‐ray crystallography revealed that both exhibit a 1D chain dimensionality. Use of the kinked tethering ligand dpa produced [Cu(OAc)₂(dpa)]_n ( 1 ), which possesses a simple chain based on dpa linkage of isolated copper ions. On the other hand, employing the straighter amide ligand 4‐pina generated {[Cu(OAc)₂(4‐pina)] · 0.5H₂O}_n ( 2 ), which exhibits {Cu₂O₂} rhomboid dimers formed through bridging acetate ligands. Weak antiferromagnetic coupling [g = 1.984(3), J = –3.2(3) cm^–1] was observed within the axial‐equatorial bridged {Cu₂O₂} dimers in 2 , with possible ferrimagnetism due to spin canting below 11 K.     

A selective fluorogenic chemodosimeter for Hg based on the dimerization of desulfurized product

A simple Hg²⁺-selective chemodosimetric system based on thiosemicarbazone was investigated. The transformation of thiosemicarbazone into semicarbazone selectively exerted by Hg²⁺ ions and the dimerization of semicarbazone resulted in a pronounced OFF–ON-type fluorescent signaling behavior. The coexistent metal ions, such as Fe³⁺, Ca²⁺, Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺, Mg²⁺, Na⁺, K⁺, and Fe²⁺, had no obvious interference with the detection of Hg²⁺. In addition, S₁₂–Hg²⁺ plays a high sensitivity for basic anions to form an ‘OFF–ON–OFF’ type signaling behavior, with the Hg²⁺-induced emission spectra can be quenched. Moreover, test strips based on S₁₂ exhibited a good selectivity to Hg²⁺. We believe the test strips could act as a convenient and efficient Hg²⁺ test kit.     

Molecular iodine catalyzed selective acetylation of alcohols with vinyl acetate

Molecular iodine is found to catalyze the acetylation of alcohols efficiently with vinyl acetate. The reaction is mild and selective with good to high yields. Molecular iodine displays significant functional group tolerance, being compatible with methoxy, double bonds, spiroketals, ketals and phenolic hydroxyl functions.     

Isothermal decomposition of γ-irradiated dysprosium acetate

Isothermal decomposition of un-irradiated and pre- n -irradiated dysprosium acetate [Dy(CH₃COO)₃] has been investigated at different temperatures between 603-623 v K. Irradiation was observed to enhance the rate of decomposition without modifying the mechanism of the thermal decomposition. Thermal decomposition of dysposium acetate is shown to proceed by a nucleation and growth mechanism (Avarmi-Erofe'ev equation) both for un-irradiated and pre- n -irradiated samples. The enhancement of the decomposition was found to increase with an increase in the n -ray dose applied to the sample and may be attributed to an increase in point defects and formation of additional nucleation centers generated in the host lattice. Thermodynamic values of the main decomposition process were calculated and evaluated.     

RP-HPLC测定眼内冲洗灌注液中柠檬酸钠与醋酸钠的含量

采用RP-HPLC同时测定眼内冲洗灌注液中柠檬酸钠与醋酸钠的含量,并对其评价。以水为流动相（用85%磷酸调至pH 2.19）,采用C₁₈色谱柱,紫外检测器210nm波长下检测。在线性范围内各成分相关系数均在0.999以上。本法首次不经分离直接测定眼内冲洗灌注液中柠檬酸与醋酸钠含量,操作简单、方法稳定、准确,可作为眼内冲洗灌注液质量控制方法之一。     

Structural and photophysical studies on a linear trinuclear zinc complex of 2-[(2-hydroxyethylimino)methyl]quinolin-8-ol

A linear trinuclear zinc complex was obtained when after refluxing 8-hydroxyquinoline-2-carboxaldehyde and 2-aminoethanol (in a 1:1 molar ratio) until the formation of the H₂L ligand, a methanol solution of zinc acetate dihydrate was added. Reaction between Zn(OAc)₂·2H₂O and H₂L, both in 3:2 or 4:2 ratios, yielded Zn₃(HL)₂(OAc)₄. This latter could be crystallographically characterised, and rather surprisingly, the potentially tetradentate HL⁻ is only acting as an O,N-donor, while two phenolate and four acetate bridges hold together the three zinc ions. A study of the luminescence properties in methanol solution showed that the quantum yield of Zn₃(HL)₂(OAc)₄ (Φ_F = 0.07) is slightly higher than that of 8-hydroxyquinoline-2-carboxaldehyde (Φ_F = 0.06).