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[en] We have prepared and fully characterized the new undulated zinc coordination polymer in which the macrocyclic ligand contains cis-fused cyclohexane rings. The bridging ligand H2pm in the complex shows the unusual coordination mode to the zinc macrocycle with the involvement of 1,5-COO. rather than 1,4-COO. in coordination. We believe that this unusual structure is caused by the involvement of complex inter- and intramolecular hydrogen bonds between the zinc macrocycle 'connectors' and H2pm 'linkers', the presence of face-to-face π.π interactions of aromatic rings between the chains as well as the enhanced rigidity and steric hindrance of the macrocycle by the introduction of cis-fused cyclohexane rings and methyl groups on the 14-membered tetraazamacrocycle. Macrocyclic transition metal complexes with polycarbox-ylate ligands have been proved to be good building blocks for the construction of coordination polymers and supramolecular networks. Coordination polymers are generally composed of metal ion 'connectors' and multidentate ligand 'linkers', and the dimensionality of coordination polymers can be tuned by controlling the coordination sites of metal ion 'connectors' for multidentate ligand 'linkers'
[en] The calcium aluminum zincates Ca14(Al1-2xTixZnx)10Zn6O35, in which Al3+ sites in the host material Ca14Al10Zn6O35 are simultaneously substituted by Ti4+ and Zn2+, were synthesized by a polymerized complex method. Al3+ ions could be replaced up to an x value of 0.1. The host material does not exhibit fluorescence, while the cation-substituted samples show an emission band centered at 383 nm under excitation by UV light at 243 nm. The emission intensity increases with x up to 0.1 and then gradually decreases as x is further increased. The emission wavelength also becomes longer with increasing temperature. Based on the properties of other Ti4+-containing fluorescent materials, the emission of Ca14(Al1-2xTixZnx)10Zn6O35 is attributed to charge transfer-type fluorescence resulting from [TiO6] octahedra.
[en] Graphical abstract: - Highlights: • The inhibiting influence of two neutral surfactants OMG and DMG on Zn2+ electroreduction was shown. • Larger inhibiting effect is observed in the presence of N-decanoyl-N-methylglucamine (DMG). • The first step is slower thus determining the rate of the whole process. • Different mechanistic schemes assuming a two-step character of Zn2+ electroreduction were discussed. • At a certain surfactant concentration the change of electroreduction mechanism is observed. - Abstract: We examined the electroreduction of Zn2+ in NaClO4 as a supporting electrolyte in the presence of neutral surfactants of various molecular sizes on a mercury electrode. The studies were carried out at different temperatures. The inhibiting effect of N-decanoyl-N-methylglucamine (DMG) on the kinetics of the investigated electrode process was stronger compared to that of N-octanoyl-N-methylglucamine (OMG). In order to describe the Zn2+ reduction in the studied systems, four mechanisms were taken into consideration: EE, CE, IA, and IE. Ion transfer was considered as the most probable first step, whereas electron transfer or reagent adsorption were postulated to be the second step of the electrode process
[en] A highly sensitive and selective coumarin based chemosensor (HL) for the efficient detection of Zn2+ cation has been developed in a very facile and economically cheap route with an excellent yield. The distinct color change on addition of Zn2+ to the sensor is visible under naked eye. Moreover the rapid enhancement of fluorescence emission intensity on addition of Zn2+ also provides a wonderful detection technique for Zn2+. The chemosensor is also efficient in detection of Zn2+ even in the presence of other metals and shows high selectivity towards Zn2+. Experimental results have been verified with DFT and TDDFT calculations. -- Highlights: • Coumarin based fluorescent ‘turn-on’ chemosensor for Zn2+. • Selective and efficient detection of Zn2+. • Study of electronic structure of chemosensor (HL) and its zinc-complex. • Theoretical calculations
[en] To explore the mechanisms and influence factors on the production of 2,4,6-trichloroanisole (2,4,6-TCA) in surface waters, the 2,4,6-TCA formation potential (FP) test was conducted by incubating the real lake water with the addition of 2,4,6-trichlorophenol (2,4,6-TCP) precursor. Besides bacteria and fungi, two common cyanobacteria and algae species, i.e., Chlorella vulgaris and Anabaena flos-aquae, have been proved to have strong capabilities to produce 2,4,6-TCA, which may contribute the high 2,4,6-TCA FP (152.2 ng/L) of lake water. The microbial O-methylation of 2,4,6-TCP precursor is catalyzed by chlorophenol O-methyltransferases (CPOMTs), and their characteristics were identified by adding inductive methyl donors or excluding microorganisms via ultrafiltration. The results indicated both S-adenosyl methionine (SAM) dependent and non-SAM dependent CPOMTs played important roles; extracellular CPOMTs also participated in the biosynthesis of 2,4,6-TCA. Moreover, investigating the effects of various environmental factors revealed initial 2,4,6-TCP processor concentration, temperature, pH and some divalent metal cations (i.e., Mn2+, Mg2+ and Zn2+) had obvious effects on the production of 2,4,6-TCA. - Highlights: • The production of 2,4,6-TCA by cyanobacteria/algae was revealed for the first time. • Both SAM dependent and non-SAM dependent CPOMTs played important roles. • Extracellular CPOMTs has been proved to participate in biosynthesis of 2,4,6-TCA. • Temperature, pH, and metal ions have obvious effects on biosynthesis of 2,4,6-TCA. • Several strategies have been proposed for the control of 2,4,6-TCA. - The biosynthesis of 2,4,6-TCA was first reported in cyanobacteria and algae species in the lake water, in which various chlorophenol O-methyltransferases were involved.
[en] Several simple Y-type 2, 3-di(2′-pyridyl or quinoyl)quinoxaline derivatives had been synthesized, which is firstly utilized for detecting zinc ion as the receptor and fluorophore. They showed significant fluorescent turn-on and ratiometric detection of Zn2+ with red shift and remarkable fluorescence ratio enhancement. In addition, these probes displayed high selectivity for zinc ion over other relevant ions. Theoretical calculations were carried out to investigate the recognition mechanism of the intramolecular charge transfer. - Graphical abstract: Several simple Y-type 2, 3-di(2′-pyridyl or quinoyl)quinoxaline derivatives had been synthesized, which is firstly utilized for detecting zinc ion as the receptor and fluorophore. They showed significant fluorescent turn-on and ratiometric detection of Zn2+ with red shift and remarkable fluorescence ratio enhancement. In addition, these probes displayed high selectivity for zinc ion over other relevant ions. Theoretical calculations were carried out to investigate the recognition mechanism of the intramolecular charge transfer. - Highlights: • Several novel Y-type quinoxaline probes were developed for zinc ion detecting. • They showed significant fluorescent turn-on and ratiometric detection of Zn2+. • These probes displayed high selectivity for zinc ion. • A new receptor for Zn2+ based on 2,3-dipyridylquinoxaline segment was exploited.
[en] It is showed by use of ph-metric titration dates and program New DALSFEK that the coordinated compounds with complex ions [Zn L]+, [ZnL2]0, [Zn(H L)]2+and the decimal logarithms of the constants formation 1gK[Zn(HL2)]=14,055, 1gK[Zn(HL2)]=12,645, 1gK[Zn(H L)2]=30,111 is formed at interaction of the Zn2+and depicted H-Gly-Trp-OH at equivalent amounts in water solutions
[en] The possibilities offered by metal implantation technics in obtaining high value resistors on insulating substrates are analyzed. Resistors of values really higher than that from diffusion in silicon are expected in view of use as discrete components as well as integrated circuit fabrication. Zn+ ion implantation in N type SiO2 substrate partially covered with a gold film is envisaged
[fr]On analyse les possibilites offertes par les techniques d'implantation d'ions metalliques dans l'obtention de resistances de hautes valeurs sur substrat isolant. Le but est d'obtenir des valeurs de resistances nettement superieures a celles obtenues actuellement par diffusion dans le silicium pour une utilisation tant au niveau du composant discret qu'au niveau de la fabrication de circuits integres. L'exemple concerne l'implantation d'ions Zn+ sur un substrat de SiO2 type N partiellement metallise a l'or
[en] We report p-type conductivity in wurtzite indium nitride (InN) experimentally and theoretically. The as-deposited InN films are implanted with various doses of Zn ions. The Hall coefficient is positive for samples with doses of 2.5 ∼ 10 × 10"1"4 ions cm"−"2 at low temperature and turns negative as the temperature increases. This notable sign change of the Hall coefficient confirms the existence of mobile holes in Zn-implanted InN. Moreover, first principle calculations indicate that Zn may be a more stable p-type dopant in InN than that of Mg and Ba because of its low ionization energy. (paper)
[en] In a recent paper Kompitsas et al. [J. Opt. Soc. Am. B 11, 697--702 (1994)] presented new spectroscopic measurements for the 4 snf levels in neutral Zn and used these results to deduce a value for the dipole polarizability αd of the Zn+ ion. We point out other data sources that are relevant to this determination and present additional analyses and computations that test the value that they reported. In this manner we have obtained the value αd(Zn+)=15.4±0.5a03, which confirms with reduced uncertainties the value reported by Kompitsas et al