557-34-6Relevant articles and documents
Zinc-containing block copolymer as a precursor for the in situ formation of nano ZnO and PMMA/ZnO nanocomposites
Kos, Tomaz,Anzlovar, Alojz,Pahovnik, David,Zagar, Ema,Orel, Zorica Crnjak,Zigon, Majda
, p. 6942 - 6948 (2013)
We report on the synthesis of highly transparent and UV-absorbing PMMA/ZnO nanocomposites prepared by hydrolysis of a ZnO precursor, the A-b-(AB) diblock copolymer, poly(methyl methacrylate)-block-poly(methyl methacrylate-co-(zinc methacrylate acetate)), PMMA-b-P(MMA-co-ZnMAAc), synthesized by RAFT polymerization. The zinc content of the block copolymers was in the range from 3 to 13 wt %. The PMMA block provides inherent compatibility with the PMMA matrix, whereas the second block, P(MMA-co-ZnMAAc) with zinc ions, acts as a polymeric precursor for the formation of ZnO nanoparticles. The amphiphilic block copolymer self-organizes in THF and THF/H2O in ordered nanostructures, thereby influencing the nanoparticle formation during the hydrolysis of the precursor block copolymer with KOH in a solvent mixture THF/H2O. The ZnO nanoparticles were rod-shaped with lengths up to 80 nm and a diameter of 14 nm and were redispersible in THF. Dispersions in THF and thin films of PMMA/ZnO nanocomposite exhibit excellent transparency in the visible range and good absorption in the UV range below 400 nm. The block copolymer was characterized by SEC, NMR, DLS, and TGA, while PMMA/ZnO nanocomposites were characterized by IR, XRD, UV-vis, and STEM.
Kinetics and mechanism of the isothermal dehydration of zinc acetate dihydrate
Koga, Nobuyoshi,Tanaka, Haruhiko
, p. 69 - 76 (1997)
The overall kinetics of the thermal dehydration of zinc acetate dihydrate was investigated by means of isothermal mass-change measurements, complemented by microscopic observations of the reaction geometry and morphological change during the reaction. Under isothermal conditions, the compound loses its water of crystallization in a well-defined single step; Zn(CH3COO)2 · 2H2O → Zn(CH3COO)2 + 2H2O. The microscopic observations for the single crystals confirm that the reaction initiates at the edge surfaces of the hexagonal thin plate by nucleation and growth processes, consequently forming the reaction interface which advances inward, toward the center of the hexagon. The kinetic results obtained from the thermoanalytical measurements indicated agreement to the first-order law, in spite of the two-dimensional shrinkage of the reaction interface. This discrepancy is discussed in connection with the interactions of the elementary nucleation and growth processes at the reaction interfaces with the self-generated water vapor. The overall kinetic behavior of the crushed crystals of different particle-size fractions, under various atmospheric conditions, was investigated. The apparent kinetic results varied systematically with the sample and atmospheric conditions, accompanied by changes of the roles of surface reaction, diffusion of evolved water vapor from the reaction interface and gross diffusion of water vapor through the assemblage of sample particles.
Thermal stability of new zinc acetate-based complex compounds
Gyoryova,Balek
, p. 519 - 532 (1993)
The compounds were characterized by IR spectroscopy, chemical analysis and thermal analysis. Thermal analysis showed that no changes in crystallographic modifications of the compounds take place during (heating in nitrogen before) the thermal decompositio
Zn(II) carboxylates containing heterocyclic secondary ligands: synthesis and structure manifestation through DFT studies
Zahoor, Ayesha,Imtiaz-Ud-Din,Andleeb, Sohaila,Raheel, Ahmad,Ayub, Rabia,Abbas, Sumaira,Tahir, Muhammad Nawaz
, p. 1978 - 1991 (2021)
New Zn(II) complexes (1–8) of general formula [Zn(R)2(L')2], where R = cinnamic acid (1–7), L' = 3-pyridine carboxamide (1), 2,2'-bipyridine (2), 3-pyridinecarbonitrile (3), 2-amino-5-(4-pyridinyl)-1,3,4-thiadiazole (4), 2-methylimidazole (5), 2-phenylimidazole (6), 2-imidazolidinethione (7) and for (8), R = acetic acid; L' = 2-amino-5-(4-pyridinyl)-1,3,4-thiadiazole)2, have been synthesized by a stoichiometric reaction between Zn(II) carboxylate(s) and the respective nitrogen-based ligands. The prepared compounds are analyzed by FTIR, NMR spectroscopy and single crystal X-ray diffraction techniques for their structural manifestations along with elemental analyses. The crystallographic data for 6 and 8 exhibit four-coordinated zinc having distorted tetrahedral molecular geometry. The thermogravimetric data demonstrate high stability of the compounds with gradual loss of acetate and thiadiazol fragments that ultimately lead to zinc oxide as the residual mass of 8. Quantum chemical calculations indicate that 7 is the softest in reactivity having the lowest band gap as determined from the energies of frontier molecular orbitals whereas 8 is highly polar with the highest dipole moment value of 12.61 D. The computational data are a complement to the success of the research.
A phosgene-free process for the synthesis of methyl N-phenyl carbamate by the reaction of aniline with methyl carbamate
Li, Qi-Feng,Wang, Jun-Wei,Dong, Wen-Sheng,Kang, Mao-Qing,Wang, Xin-Kui,Peng, Shao-Yi
, p. 99 - 105 (2004)
A phosgene-free route for the synthesis of methyl N-phenyl carbamate (MPC) by the reaction of aniline with methyl carbamate in the presence of methanol was studied. Effects of catalysts, reaction temperature, reaction time, and catalyst content, the molar ratio of reactants and the content of water on the reaction were investigated. The results demonstrated that an aniline conversion of 90.1% and MPC selectivity of 99.7% were achieved when the reaction was carried out at 433 K for 4 h using ZnCl2 as a catalyst. A possible reaction mechanism was proposed based on the product distribution.
Controllable fabrication of various ZnO micro/nanostructures from a wire-like Zn-EG-AC precursor via a facile solution-based route
Tian, Chungui,Li, Wei,Zhang, Qi,Pan, Kai,Fu, Honggang
, p. 1283 - 1289 (2011)
In this paper, ZnO particles with various morphologies were prepared though a facile solution-based route. The complexes Zn-EG-AC (EG: ethylene glycol; AC: CH3COO- groups) obtained by reaction of anhydrous zinc acetate and EG were used as precursors. It is found that the precursor could transform into ZnO in water with no need of assistant of additional alkali as it is sensitive to water. At the same time, it is well dispersed in reaction medium (water and ethanol). Experimental results showed that ZnO particles with various morphologies, such as the hexagonal rings, the hexagonal plates, the tubes, the prisms, and some interesting hierarchical structures, could be obtained by controlling hydrolysis of precursor in water and water/ethanol medium through finely tuning the experimental parameters. The success of shape-controllable fabrication was related intimately with the Zn-EG-AC precursor used in our synthesis.
Zinc-67 NMR study of tetrahedral and octahedral zinc sites with symmetrical oxygen, nitrogen, and sulfur ligands
Sham, Simon,Wu, Gang
, p. 1782 - 1787 (1999)
We report a 67Zn nuclear magnetic resonance (NMR) study of compounds containing zinc ions coordinated by oxygen, nitrogen, and sulfur ligands. New information concerning 67Zn nuclear quadrupole coupling constants (NQCC) and chemical shift was obtained from magic-angle spinning (MAS) spectra of solid compounds containing both natural abundance and enriched 67Zn isotopes. Rapid ligand exchange processes of [Zn(thiourea)4]2+ in aqueous solutions were also observed.
Davidson, A. W.,McAllister, W. H.
, p. 519 - 527 (1930)
COMPACT AND HOMOGENEOUS QUANTUM DOTS AND METHODS OF MAKING THE SAME
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, (2020/02/10)
The present disclosure provides quantum dots and methods of making the quantum dots comprising a substantially homogeneous population of monomeric nanocrystals, of a very small size, about 7 nm to about 12 nm in diameter. The method comprises mixing a nanocrystal coated with weakly binding ligands or ions with a polymer in a solution and incubating at a temperature greater than about 100° C., thereby forming a quantum dot having a substantially homogenous population of monomeric nanocrystals. The quantum dots can be further conjugated to bioaffinity molecules, enabling broad utilization of compact, biofunctional quantum dots for studying crowded macromolecular environments.
Oral Care Compositions and Methods of Use
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Paragraph 0104-0105, (2019/02/05)
Disclosed herein are oral care compositions including Zn:usnate complexes having a 1:2 zinc to usnate molar ratio. Methods of making and using the compositions are also provided.
