An Au/SnO-SnO2 nanosheet based composite used for rapid detection of hydrogen sulphide.

In this work, a new type of H2S sensor was fabricated by means of drop-coating of an Au/SnO-SnO2 nanosheet material, which was prepared by a one-pot hydrothermal reaction, onto a gold electrode in an alumina ceramic tube with the formation of a thin nanocomposite film. The microstructure and morphology of the nanosheet composites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A gas-sensitivity study presented good H2S-sensing performance of such Au/SnO-SnO2 nanosheet composites. At an optimal operating temperature of 240 °C and ambient temperature of 25 °C, the resulting sensor showed a good linear response to H2S in a range of 1.0 to 100 ppm with a low detection limit of 0.7 ppm, and a very fast response-recovery time of 22 s for response and 63 s for recovery, respectively. The sensor was also unaffected by ambient humidity and had good reproducibility and selectivity. When being applied to the monitoring of H2S in an atmospheric environment in a pig farm, the response signal to H2S was only attenuated by 4.69% within 90 days, proving that the sensor had a long and stable service lifetime for continuous running and showing its important practical application prospects.

ZnO@CuO hollow nanosphere-based composites used for the sensitive detection of hydrogen sulfide with long-term stability.

In this study, zinc oxide@cupric oxide hollow nanospheres (ZnO@CuO HNS, 330 nm in diameter) were successfully prepared by a hard-template method using amino-phenolformaldehyde resin spheres (APF) as the templates. A new type of thin-film gas sensor toward hydrogen sulfide (H2S) was fabricated by means of drop-coating on the gold electrode of an alumina ceramic tube. The microstructure and morphology of the nanosphere composites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the gas-sensing performance of the composites toward the detection of H2S were investigated. The ZnO@CuO nanocomposite with a hollow structure exhibited good gas-sensing properties. Under the optimum operating temperature of 260 °C, ambient temperature of 30 °C, and ambient humidity of 70%, the linear response of the sensor to H2S was in the concentration range of 0.1-100 ppm, and its detection limit reached 0.0611 ppm, with a quick response time of 78 s. Also, the sensor possessed good repeatability, selectivity, and stability. The long-term stability and run duration of such sensors were pronounced, with only a 1.9% reduction in the signal after the continuous monitoring of H2S gas in a pig farm for 18 months using Alibaba's cloud remote transmission system, which presents an important practical application prospect in atmosphere environment monitoring on livestock-raising fields.

A Bifunctional Luminescent Metal-Organic Framework for the Sensing of Paraquat and Fe3+ Ions in Water.

The hydrothermal reaction of Zn2+ ions with a mixture of two ligands, Hcptpy and H3 btc (Hcptpy=4-(4-carboxyphenyl)-2,2':4',4''-terpyridine; H3 btc=1,3,5-benzenetricarboxylic acid), led to the formation of a 3D metal-organic framework (MOF) with 1D channels, [Zn2 (cptpy)(btc)(H2 O)]n (1), which was structurally characterized by using single-crystal X-ray diffraction (SXRD). In MOF 1, two independent Zn2+ ions were interconnected by btc3- ligands to form a 1D chain, whilst adjacent Zn2+ ions were alternately bridged by cptpy- ligands to generate a 2D sheet, which was further linked by 1D chains to form a 3D framework with a new (3,3,4,4)-connected topology. Furthermore, compound 1 also exhibited excellent stability towards air and water and, more importantly, luminescence experiments indicated that it could serve as a probe for the sensitive detection of paraquat (PAQ) and Fe3+ ions in aqueous solution.

Prediction of boiling points of organic compounds by QSPR tools.

The novel electro-negativity topological descriptors of YC, WC were derived from molecular structure by equilibrium electro-negativity of atom and relative bond length of molecule. The quantitative structure-property relationships (QSPR) between descriptors of YC, WC as well as path number parameter P3 and the normal boiling points of 80 alkanes, 65 unsaturated hydrocarbons and 70 alcohols were obtained separately. The high-quality prediction models were evidenced by coefficient of determination (R(2)), the standard error (S), average absolute errors (AAE) and predictive parameters (Qext(2),RCV(2),Rm(2)). According to the regression equations, the influences of the length of carbon backbone, the size, the degree of branching of a molecule and the role of functional groups on the normal boiling point were analyzed. Comparison results with reference models demonstrated that novel topological descriptors based on the equilibrium electro-negativity of atom and the relative bond length were useful molecular descriptors for predicting the normal boiling points of organic compounds.

A novel fluorescent probe for copper ions based on polymer-modified CdSe/CdS core/shell quantum dots.

Quantum dots (QDs) have become one of the most attractive fields of current research because of their unique optical properties. Novel copper-sensitive fluorescent fluoroionophores based on CdSe/CdS core/shell QDs modified with a polymer of MAO-mPEG were synthesized and characterized in the present work. A pH of 6.47 was optimally selected for measurements. By modifying QDs with MAO-mPEG, significant aqueous fluorescence quenching was observed upon binding with copper ions involving both reduced and oxidized environments, indicating great sensitivity and specificity for copper-ion sensing. No significant interfering effects from other metal ions, such as Ag(+), Al(3+), Ba(2+), Ca(2+), Cd(2+), Co(2+), Cr(3+), Fe(2+), Fe(3+), Hg(2+), K(+), Mg(2+), Mn(2+), Na(+), Ni(2+), Pb(2+), Sn(2+), and Zn(2+), were observed. The linear response range for Cu(2+) was found to be 0.01-0.50 µM, and the limit of detection was evaluated to be 16 nM. The proposed method demonstrated improved sensitivity and selectivity characteristics for Cu(II) determinations based on CdSe/CdS core/shell QDs modified with MAO-mPEG by using a typical liquid-phase quenching assay, showing its potential application to multiplex sensing of different analytes through distinct ligand conjugation and functionalization of individual fluorophores.

A reusable capacitive immunosensor based on a CuS ultrathin film constructed by using a surface sol-gel technique.

A capacitive sensing method based on a CuS ultrathin film modified electrode prepared by a surface sol-gel technique has been developed for the direct detection of human IgA. The resulting CuS film was investigated with cyclic voltammetry (CV), impedance spectroscopy, and quartz crystal microbalance (QCM). CV and impedance examinations showed that the CuS film formed on the gold electrode surface was insulated, and was applicable to form an insulating layer of a capacitive immunosensor. With QCM measurements, the thickness of the CuS film was evaluated to be 5.8 nm. The capacitance change was greatly increased by a CuS nanofilm-based immunosensor, which was initiated by the recognition of an immobilized antibody and the target antigen. The capacitance of the immunosensor corresponding to the concentration of human IgA was investigated by potentiostatic-step measurements. A linear calibration curve was obtained in the range of 1.81 - 90.5 ng ml(-1) with a detection limit of 1.81 ng ml(-1). There were no obvious interferences from the nonspecific adsorption of other proteins. With nice reproducibility and regeneration capacity, the CuS ultrathin film modified immunosensor could be used for the detection of human IgA in serum samples with a recovery of 96.1 - 104.4%, showing its promising applicability and reliability.

Triaqua(2-{[(E)-5-formyl-2-oxidobenzyl-idene]amino}ethanesulfonato)cobalt(II) dihydrate.

The title compound, [Co(C(10)H(9)NO(5)S)(H(2)O)(3)]·2H(2)O, is a cobalt-Schiff base complex derived from taurine. There are two complex mol-ecules and four solvent water mol-ecules in the asymmetric unit. The central Co atom is six coordinated by two O atoms and one N atom of the ligand and three O atoms of water mol-ecules, forming a slightly distorted octa-hedral geometry. The crystal structure is stabilized by several O-H⋯O hydrogen bonds.

Di-mu-hydroxo-bis[aqua(1,10-phen-anthroline-kappa2N,N')copper(II)] trans-bis(2-([(E)-5-formyl-2-oxido-kappaO-benzylidene]amino-kappaN)ethanesulfonato(2-))copper(II) hexahydrate.

The title compound, [Cu(2)(OH)(2)(C(12)H(8)N(2))(2)(H(2)O)(2)][Cu(C(10)H(9)NO(5)S)(2)].6H(2)O, is comprised of a copper-centred complex cation and a copper-centred complex anion; the cation lies about an inversion centre and in the anion the Cu atom lies on an inversion centre. In the doubly charged bridged dicopper cation, each Cu centre has distorted square-pyramidal geometry. In the square-planar dianion, two sulfonate ligands are trans coordinated to the Cu atom via a deprotonated hydroxyl O atom and an imine N atom, forming two six-membered chelate rings. The structure is stabilized by an extensive hydrogen-bond system and aromatic-ring stacking interactions.