1.Concentration dependence of luminescence efficiency of Dy3 + ions in strontium zinc phosphate glasses mixed with Pb3 O4.
Kumar VR1,2, Giridhar G1, Veeraiah N2. Luminescence. 2016 Apr 27. doi: 10.1002/bio.3150. [Epub ahead of print]
In this work we synthesized SrO-ZnO-P2 O5 glasses mixed with Pb3 O4 (heavy metal oxide) and doped with different amounts of Dy2 O3 (0.1 to 1.0 mol%). Subsequently their emission and decay characteristics were investigated as a function of Dy2 O3 concentration. The emission spectra exhibited three principal emission bands in the visible region corresponding to 4 F9 /2 → 6 H15 /2 (482 nm), 6 H13 /2 (574 nm) and 6 H11 /2 (663 nm) transitions. With increase in the concentration of Dy2 O3 (upto 0.8 mol%) a considerable increase in the intensity of these bands was observed and, for further increase, quenching of photoluminescence (PL) output was observed. Using emission spectra, various radiative parameters were evaluated and all these parameters were found to increase with increase in Dy2 O3 concentration. The Y/B integral emission intensity ratio of Dy3 + ions evaluated from these spectra exhibited a decreasing trend with increase in the Dy2 O3 concentration up to 0.
2.Applying Mechanochemistry for Bottom-Up Synthesis and Host-Guest Surface Modification of Semiconducting Nanocrystals: A Case of Water-Soluble β-Cyclodextrin-Coated Zinc Oxide.
Krupiński P1, Kornowicz A2, Sokołowski K1, Cieślak AM1, Lewiński J3,4. Chemistry. 2016 Apr 26. doi: 10.1002/chem.201600182. [Epub ahead of print]
Mechanochemistry has recently emerged as an environmentally friendly solventless synthesis method enabling a variety of transformations including those impracticable in solution. However, its application in the synthesis of well-defined nanomaterials remains very limited. Here, we report a new bottom-up mechanochemical strategy to rapid mild-conditions synthesis of organic ligand-coated ZnO nanocrystals (NCs) and their further host-guest modification with β-cyclodextrin (β-CD) leading to water-soluble amide-β-CD-coated ZnO NCs. The transformations can be achieved by either one-pot sequential or one-step three-component process. The developed bottom-up methodology is based on employing oxo-zinc benzamidate, [Zn4 (μ4 -O)(NHOCPh)6 ], as a predesigned molecular precursor undergoing mild solid-state transformation to ZnO NCs in the presence of water in a rapid, clean and sustainable process.
3.The biological inorganic chemistry of zinc ions.
Krężel A1, Maret W2. Arch Biochem Biophys. 2016 Apr 23. pii: S0003-9861(16)30130-8. doi: 10.1016/j.abb.2016.04.010. [Epub ahead of print]
The solution and complexation chemistry of zinc ions is the basis for zinc biology. In living organisms, zinc is redox-inert and has only one valence state: Zn(II). Its coordination environment in proteins is limited by oxygen, nitrogen, and sulfur donors from the side chains of a few amino acids. In an estimated 10% of all human proteins, zinc has a catalytic or structural function and remains bound during the lifetime of the protein. However, in other proteins zinc ions bind reversibly with dissociation and association rates commensurate with the requirements in regulation, transport, transfer, sensing, signalling, and storage. In contrast to the extensive knowledge about zinc proteins, the coordination chemistry of the "mobile" zinc ions in these processes, i.e. when not bound to proteins, is virtually unexplored and the mechanisms of ligand exchange are poorly understood. Knowledge of the biological inorganic chemistry of zinc ions is essential for understanding its cellular biology and for designing complexes that deliver zinc to proteins and chelating agents that remove zinc from proteins, for detecting zinc ion species by qualitative and quantitative analysis, and for proper planning and execution of experiments involving zinc ions and nanoparticles such as zinc oxide (ZnO).
4.Multi-surface modeling to predict free zinc ion concentrations in low-zinc soils.
Duffner A1, Weng L, Hoffland E, van der Zee SE. Environ Sci Technol. 2014 May 20;48(10):5700-8. doi: 10.1021/es500257e. Epub 2014 Apr 30.
Multi-surface models are widely used to assess the potential ecotoxicological risk in metal-contaminated soils. Their accuracy in predicting metal speciation in soils with low metal levels was not yet tested. Now highly sensitive analytical techniques are available to experimentally validate such models at low concentration levels. The objective of this study was to test the accuracy of a multi-surface model to predict the Zn(2+) concentration and to improve our understanding of Zn bioavailability in low-Zn soils. High-Zn soils were included as controls. Model parameters were determined independently on the basis of earlier peer-reviewed publications. Model output was validated against free Zn(2+) concentrations determined with the soil column Donnan membrane technique in a range of soils varying in potentially available Zn, organic matter, clay silicate, and iron (hydr)oxide contents and pH. Deviations between predicted Zn(2+) concentrations and experimentally determined values over the whole Zn concentration range were less or equal to the experimental standard error, except for one low-Zn soil.