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Synthesis and Characterization of Metal–Organic Frameworks
Published in T. Grant Glover, Bin Mu, Gas Adsorption in Metal-Organic Frameworks, 2018
The structure of the inorganic cluster composed of metal ions and linker terminals is dependent on the type and oxidation state of metal ions.16 Therefore, the selection of metal ions is critical to design MOFs with a desirable connectivity (topology). Although most of the metals are used as a component of MOFs, unlike various metal salts, it is rare that metallic elements and metal oxides are used as metal sources due to limited solubility in polar aprotic solvents.17,18 Commonly used metal salts are either hydrated or anhydrous metal nitrate (e.g., Al, Cu, Co, Mg, Ni, and Zn), acetate (e.g., Cu, Ni, and Zn), chloride (e.g., Co, Fe, Mn, Ni, Hf, Ti, V, Zn, and Zr), and sulfate (e.g., Fe). Metal perchlorates could also be used, but special caution is required because of their explosive nature. It is presumed that pH of the reaction mixture is influenced by the counter anion of the metal salts, which changes the rate of MOF formation (linker deprotonation). For example, a reaction in a copper, acetate solution is much faster than that in a copper nitrate solution (e.g., immediate precipitation of microcrystalline powder from the copper acetate solution even at room temperature). In addition to these metal salts, metal alkoxides, such as titanium(IV) isopropoxide, are employed to form MOF structures.19
Thin-Layer Chromatography in Food Analysis
Published in Bernard Fried, Joseph Sherma, Practical Thin-Layer Chromatography, 2017
A number of substances can be incorporated into thin layers or added to them to yield layers for specific separations.36,61,64–66 The pH of layers can be varied widely by using aqueous solutions of acids, bases, and buffers (0.5 N in slurry) for the separation of acids, bases, and acidic or basic substances depending on the type of buffer used, respectively. Complexing agents are most important, e.g., boric acid (0.1 N in slurry) for the separation of sugars; silver nitrate (12.5% in slurry) for separation of saturated from unsaturated fatty acids; and, 2,4,7-trinitrofluorenone (0.3% in adsorbent) for the separation of aromatic hydrocarbons. 61 Chiral plates are composed of a reversed-phase layer impregnated with copper acetate.67 If precoated plates are used, they can be dipped into a solution of the substance in a tray and then redried. Some care may be needed to ensure that impregnation occurs evenly.36
Polymers
Published in Bryan Ellis, Ray Smith, Polymers, 2008
Friction Abrasion and Resistance: Abrasion resistance 20 mg (Elf- Aquitaine test) [1]. The influence of fillers (ZnS, PbS, ZnF2) on transfer film formation was studied by optical and scanning electron microscopy. PbS dissociates during wear and forms a strong adherent film which improves wear resistance. The other fillers increase wear relative to unfilled Nylon 11 [47]. 35 vol% PbS gives the best wear resistance. Wear rate increases considerably upon doubling applied force and speed, and when increasing the surface roughness; coefficient of friction is not affected [44]. With copper fillers (CuS, CuF2, CuO, CuAc), only copper acetate has an adverse effect upon wear rate; the other composites transfer well to the steel counterface to give strongly adherent thin films [48]. Transfer films of CuS and CuF2 decompose under rubbing conditions and produce copper, FeF6 and FeSO4. Highest concentrations are closer to the transfer film-counterface interface. No chemical change is observed with copper acetate [49]. The wear rate of Nylon 11 composites containing CuS filler and short fibres, (CuS has an unusual ability to reduce wear in a number of polymers) is lowest for 20% volume carbon fibre and further reduces in the presence of CuS filler. Synergistic behaviour between the carbon fibre and CuS filler occurs as the filler decomposes which increases adhesion of the composite surface to the steel substrate. A theoretical model for the optimal filler proportion in polymer composites has been reported. [46] Scratch resistance 6 kg (0.4 mm coating on steel) [1] Charpy:
Heterometallic Cu(II)-M(II) (M = Mg, Ca and Sr) complexes with a N,O-donor ligand in situ generated from topiroxostat
Published in Journal of Coordination Chemistry, 2020
Xiang Chang, Li-Ting Jiang, Sheng-Chun Chen, Ming-Yang He, Qun Chen
A mixture of Cu(OAc)2·H2O (10.0 mg, 0.05 mmol), Mg(NO3)2·6H2O (25.6 mg, 0.1 mmol), topiroxostat (24.8 mg, 0.1 mmol), and deionized water (6 mL) was stirred for 15 min at room temperature. An aqueous NH3 solution (25%, 0.4 mL) was dropped into the mixture to generate a clear solution. The resultant solution was transfered to a 15 mL Teflon-lined stainless steel container. The container was heated to 160 °C and held at that teperature for 3 days, then cooled to room temperature at a rate of 5 K·h−1. Purple needle crystals of 1 suitable for X-ray diffraction were collected in ca. 43% yield (18.1 mg, based on copper acetate). Anal. Calcd. for C52H64Cu2Mg2N20O26 (%): C, 40.01; H, 4.13; N, 17.95. Found: C, 40.61; H, 4.14; N, 17.78. IR (cm−1, KBr): 3442 br, 1610s, 1459 w, 1405s, 1313 w, 1265 w, 1158 w, 1123 w, 1009 w, 762 w, 717 w, 583 w.
DFT studies of temperature effect on coordination chemistry of Cu(II)-trimethoprim complexes
Published in Journal of Coordination Chemistry, 2018
Malik Zaheer Ahmed, Uzma Habib
The DFT study presented in this article is mainly focused on the (a) formation of trimethoprim complexes with copper acetate as reported in the literature and (b) coordination chemistry of trimethoprim complexes 1, 2 and 3. Literature shows that, at 352 K temperature, two different geometrical complexes (olive-green colored) are formed. It shows that just by changing the temperature, different geometrical complexes were obtained with different number of atoms and of different colors. These complexes obtained also show different antibacterial activities while distorted square planar complex (light-blue colored) is formed at 298 K in which three copper atoms are involved in complex formation. These three copper atoms are linked with each other through acetate and hydroxide bridging.
Synthesis, crystal structure, theoretical calculation, and DNA binding of a copper (II) complex with 3,5-dibromo-L-tyrosine
Published in Inorganic and Nano-Metal Chemistry, 2021
Ziao Zong, Gui-Mei Huang, Xia Zhang, Yu-Hua Fan, Cai-Feng Bi, Dong-Mei Zhang, Xing-Chen Yan, Nan Zhang
Potassium hydroxide (0.056 g, 1.0 mM) was added to the solution of L1 (0.339 g, 1.0 mM) in absolute methanol (20 mL) with stirring. Then, copper acetate (0.199 g, 1.0 mM) was dissolved in 10 mL of anhydrous methanol, which was added into the reaction mixture. The reaction was kept for 4 h at 50 °C. Finally, the mixture was cooled at room temperature and filtered. The filtrate was left for slow evaporation at room temperature. The block-shaped crystal with blue color was formed after one week. C38H44Br8Cu2N4O16: Calcd. C 28.90, H 2.81, N 3.55%; Found. C 28.85, H 2.86, N 3.50%. IR (KBr): 3287 br, 1620s, 1553 w, 1479s, 1408 m, 1386 m, 1351 w, 1290 m, 1241 m, 1144 m, 738 m, 668 m, 568 w, 494 w cm−1.