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Systems Based on Silicon Selenides
Published in Vasyl Tomashyk, 2 Semiconductors, 2022
Three compounds, Cs4SiSe4, Cs4Si2Se8, and Cs4Si4Se10 are formed in the Si–Cs–Se ternary system. First of them crystallizes in the cubic structure with the lattice parameter a = 1414.7 ± 0.3 pm (Schlirf et al. 2000). The title compound was prepared starting from an inhomogeneous sample obtained by thermal decomposition of CsN3 mixed with SiSe2 (molar ratio 6:2) at 410°C in a quartz ampoule. Together with additional Se, corresponding to a molar composition Cs/Si/Se = 6:2:6, the raw product was heated to 900°C. After quenching in ice-water, homogenization and subsequent annealing at 580°C for 17 days, the reaction yielded air sensitive, pale yellow single crystals of Cs4SiSe4.
Synthesis and Characterization of Metal–Organic Frameworks
Published in T. Grant Glover, Bin Mu, Gas Adsorption in Metal-Organic Frameworks, 2018
A reaction mixture is commonly prepared in air; however, if starting materials are air (oxygen and/or water) sensitive (e.g., FeCl2 for Fe2+-based MOF23), all chemicals and equipment must be handled under inert atmosphere (i.e., under N2 or Ar). Although the Schlenk line technique is well established for handling air-sensitive materials, this is not the best way to weigh solid starting materials. Therefore, a glovebox filled with N2 or Ar is often used to synthesize air-sensitive MOF materials. For the successful manipulation of air-sensitive materials, reaction vessels (e.g., glass vials) should be heated in the drying oven for 30–60 min before moving them into the glove box. If materials (e.g., plastic caps) cannot be heated, it is better to keep them under vacuum in the glove box antechamber overnight. All chemicals used in the glove box must be purified before bringing them into the glove box or purchased from reliable vendors, and, if necessary, the water content in solvents is tested by a benzophenone ketyl test.24
Hazards
Published in Rick Houghton, William Bennett, Emergency Characterization of Unknown Materials, 2020
Rick Houghton, William Bennett
Barium hydride (BaH2) is pyrophoric in powdered form. Diisobutylaluminum hydride is air sensitive and water reactive. Both of these materials produce a basic fume, detectible with water moistened pH test strips. A colorimetric spot test for barium and aluminum would identify them if identification is necessary. All of these hydrides will react similarly and pose similar hazards with the exception of radioactive plutonium hydride.
Evaluation of anti-bacterial activity of novel 2, 3-diaminoquinoxaline derivatives: design, synthesis, biological screening, and molecular modeling studies
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Suresh Kumar Suthar, Narendra Singh Chundawat, Girdhar Pal Singh, José M. Padrón, Pavan V. Payghan, Yuvraj Kunwar Jhala
General reagents and solvents for the synthesis of compounds were analytical grade (AR) and used without further purification. Air-sensitive reactions were carried out under dry nitrogen or argon atmosphere. Thin-layer chromatography was performed on silica gel plates (Merck Silica Gel 60, F254), and the spots were visualized under UV light (254 and 365 nm). All melting points were recorded on open glass capillary tubes using the Stuart Digital Melting Point SMP10 and are uncorrected. 1H NMR was recorded at 500 MHz (Bruker DPX) frequency and 13C NMR spectra were recorded at 150.85 MHz (Bruker DPX) in DMSO-d6 or CDCl3 solvent using tetramethylsilane (TMS) as the internal standard. Mass spectra were measured with ESI ionization in MSQ LCMS mass spectrometer. Flash column chromatography was carried out using silica gel (Merck, 230–240 mesh) and Key intermediate (3a-d) were eluted in n-pentane/ethyl acetate as a mobile phase and the pure product (4a-z) were purified from recrystallization (diether ether). The coupling constant was recorded in Hz. The following abbreviations are used to explain the multiplicities: s = singlet, d = doublet, dd = doublet of doublets, dt = doublet of triplets, t = triplet, q = quartet, m = multiplet.
Synthesis and electronic structure of a series of first-row transition-metal pyrazine(diimine) complexes in two oxidation states
Published in Journal of Coordination Chemistry, 2022
Daniela Sanchez Arana, Jaylan R. Billups, Bruno Donnadieu, Sidney E. Creutz
All manipulations of air-sensitive compounds and reactions were carried out under an atmosphere of argon using standard Schlenk techniques or in a nitrogen filled LC Technologies, Inc. glovebox. Solvents were degassed by sparging with argon and purified by passage over molecular sieves in an LC Technologies Solvent Purification System and stored over 4 Å molecular sieves. THF and diethyl ether were additionally filtered over activated alumina. 2,6-Diacetyl-3,5-dimethylpyrazine was synthesized as previously reported [10]. All other chemicals were purchased commercially from Sigma Aldrich, TCI, and Alfa Aesar and used without purification. NMR spectra were recorded on a 300 MHz or 500 MHz Bruker AVANCE III and referenced internally using the residual solvent proton and carbon peaks. UV-Vis spectra were recorded on a Perkin Elmer Lambda 900 spectrometer. Cyclic voltammetry was obtained from a CH Instruments Electrochemical Analyzer in acetonitrile solution with 0.1 M TBAPF6 electrolyte or THF solution with 0.3 M TBAPF6 electrolyte, using a 3 mm glassy carbon working electrode from CH Instruments, platinum wire counter electrode, and silver wire pseudoreference electrode inside the glovebox. Solution resistance was compensated at 99% using positive-feedback iR compensation. All CVs were run at room temperature and internally referenced against Fc/Fc+, and were collected at a scan rate of 100 mV/s unless otherwise stated. Elemental analyses were measured in an UNICUBE Elementar analyzer.
Star-shaped Pd(II) and Pt(II) complexes containing C3-symmetric conjugated thiophenes: Synthesis, characterization, and chemical reactions with organic unsaturated molecules
Published in Journal of Coordination Chemistry, 2022
Hee Kwon Park, Min Gyu Ham, Yong-Joo Kim, Katsuhiko Takeuchi, Jun-Chul Choi
All manipulations of air-sensitive compounds were performed under N2 or Ar by Schlenk-line techniques. Solvents were distilled from Na–benzophenone. The analytical laboratories at Kangwon National University (Samcheok) carried out elemental analyses. IR spectra were recorded on a Perkin Elmer BX spectrophotometer. NMR (1H, 13C{1H}, and 31P{1H}) spectra were obtained in CDCl3 on a JEOL Lamda 300, JNM-ECZ 400, and ECA 600 MHz spectrometer. Chemical shifts were referenced to internal SiMe4 and to external 85% H3PO4 and external CFCl3. X-ray reflection data were obtained at the Korea Basic Science Institute (Seoul Center). Complexes trans-PdEt2(PMe3)2 and cis-PtEt2(PMe3)2 were prepared by the literature method [23,24]; 1,3,5-tris[5-(2-chlorothienyl)]benzene [8], 1,3,5-tris[5-(2-bromothienyl)]benzene [9,10], 2,4,6-tris(5-bromothiophen-2-yl)-1,3,5-triazine [11–14] and tris[4-(5-bromothiophen-2-yl)phenyl]amine [15] were prepared by literature methods. Allyl(cyclopentadienyl)palladium(II), [(η5-C5H5)Pd(η3-C3H5)], was purchased from Strem. Co. or prepared by the literature method [25].