The Bishydridobis(tetrazol-1-yl)borate Anion, [H2B(CHN4)2]-: Synthesis and Structure of the First Tetrazolylborate

Potassium bishydridobis(tetrazol-1-yl)borate (1) has been synthesized from KBH4 and tetrazole and characterized spectroscopically. Its crystal structure has been determined. 1 crystallizes in the monoclinic space group P21/n with a = 537.8(2), b = 1703.5(9), c = 919.6(3) pm, β = 106.12(3)° and V = 809.4(6)· 106 pm3

Concentration dependent tautomerism in green [Cu(HL1)(L2)] and brown [Cu(L1)(HL2)] with H2L1 = (E)-N’-(2-hydroxy-3-methoxybenzylidene)- benzoylhydrazone and HL2 = pyridine-4-carboxylic (isonicotinic) acid

The in situ formed hydrazone Schiff base ligand (E)-N’-(2-hydroxy-3-methoxybenzylidene)-benzoylhydrazone (H2L1) reacts with copper(II) acetate in ethanol in the presence of pyridine-4-carboxylic acid (isonicotinic acid, HL2) to green-[Cu(HL1)(L2)]・H2O・C2H5OH (1) and brown-[Cu(L1)(HL2)] (2) complexes which crystallize as concomitant tautomers where either the mono-anion (HL1)- or di-anion (L1)2- of the Schiff base and simultaneously the pyridine-carboxylate (L2)- or the acid (HL2) (both through the pyridine nitrogen atom) function as ligands. The square-planar molecular copper(II) complexes differ in only a localized proton position either on the amide nitrogen of the hydrazone Schiff base in 1 or on the carboxyl group of the isonicotin ligand in 2. The proportion of the tautomeric forms in the crystalline solid-state can be controlled over a wide range from 1:2 = 95 : 5 to ~2 : 98 by increasing the solution concentration. UV/Vis spectral studies show both tautomers to be kinetically stable (inert), that is, with no apparent tautomerization, in acetonitrile solution. The UB3LYP/6-31+G* level optimized structures of the two complexes are in close agreement with experimental findings. The solid-state structures feature 1D hydrogen-bonded chain from charge-assisted O(-) … H–N and O–H … (-)N hydrogen bonding in 1 and 2, respectively. In 1 pyridine-4-carboxylate also assumes a metal-bridging action by coordinating a weakly bound carboxylate group as a fifth ligand to a Cu axial site. Neighboring chains in 1 and 2 are connected by strong π-stacking interactions involving also the five- and six-membered, presumably metalloaromatic Cu-chelate rings

Redetermination of diaqua­tetra­kis­(dimethyl­formamide-κO)magnesium dichloride

The crystal structure of the title compound, [Mg(C3H7NO)4(H2O)2]Cl2, in which the Mg ion lies on a crystallographic inversion centre, confirms that of the previous room-temperature study [Pavanello et al. (1995 ▶). Main Group Met. Chem. 18, 9–19]. This redetermination at 113 K has improved geometry precision by almost an order of magnitude [e.g. Mg—O(w) (w = water) distances = 2.094 (4) and 2.0899 (7) Å in the old and new structures, respectively] and allowed the water H atoms to be located and their positions refined. In the crystal, O—H⋯Cl hydrogen bonds between the two aqua ligands of the complex mol­ecule and neighboring chloride counter-anions generate supra­molecular chains propagating along [010]. The dicationic [Mg(DMF)4(H2O)2] unit (DMF is dimethyl­formamide) adopts a slightly distorted octa­hedral geometry in which the Mg atom is coordinated by four DMF O atoms in a pseudo-tetra­gonal arrangement and two trans aqua ligands

Versatility, Cost Analysis, and Scale-up in Fluoride and Arsenic Removal Using Metal-organic Framework-based Adsorbents

Fluoride and arsenic are hazardous inorganic contaminants due to associated health risks and relatively higher levels of occurrence in groundwater. Metal-organic frameworks, (MOFs) with their high surface area, versatile building blocks and numerous active sites, are a novel approach to fluoride and arsenic uptake. This review presents the different types of MOFs for fluoride and arsenic removal along with a study of dynamic breakthrough times and cost analysis. MOF performances are based on a variety of synthesis methods, notable among which solvothermal one is more described. However, all research works concluded that MOFs have poor yield compared to conventional adsorbents. But, their high adsorption capacity, tailored chemical structure and ionic uptake of fluoride and arsenic make them a more favorable option than many other adsorbents. The cost of different MOFs usually varies between 0.1 and 5 US$/g depending on the synthesis routes

Los números

128 páginas.La teoría de los números ocupa un peculiar y distinguido lugar entre las diversas ramas de las matemáticas. Que su objetivo principal sea el estudio de algo tan conocido y familiar como son los enteros, sus propiedades y sus relaciones, explica el interés que ha suscitado siempre entre muchos ciudadanos, quienes, aun careciendo de la formación matemática apropiada, se sienten fascinados por sus problemas, tan fáciles de enunciar y, sin embargo, tan difíciles a veces de resolver. Este libro no pretende ser, ni mucho menos, un tratado de la teoría de los números, sino tan sólo un vehículo que permita al lector pasear por algunos de sus parajes más asequibles. Una especie de guía turística para aritméticos aficionados y para todos aquellos que tengan curiosidad acerca de las propiedades de los números y aprecien el arte de engarzar las ideas que conlleva todo razonamiento matemático.Peer reviewe

Formation of Gold Nanoclusters from Goldcarbonyl Chloride inside the Metal-Organic Framework HKUST-1

Gas-phase infiltration of the carbonylchloridogold(I), Au(CO)Cl precursor into the pores of HKUST-1 ([Cu$_3$(BTC)$_2$(H$_2$O)$_2$], Cu-BTC) SURMOFs (surface-mounted metal-organic frameworks; BTC = benzene-1,3,5-tricarboxylate) leads to Au(CO)Cl decomposition within the MOF through hydrolysis with the aqua ligands on Cu. Small Au$_x$ clusters with an average atom number of x ≈ 5 are formed in the medium-sized pores of the HKUST-1 matrix. These gold nanoclusters are homogeneously distributed and crystallographically ordered, which was supported by simulations of the powder X-ray diffractometric characterization. Au$_x$@HKUST-1 was further characterized by scanning electron microscopy (SEM) and infrared reflection absorption (IRRA) as well as Raman spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectroscopy (ICP-OES)

Metal-Organic Frameworks in Germany: from Synthesis to Function

Metal-organic frameworks (MOFs) are constructed from a combination of inorganic and organic units to produce materials which display high porosity, among other unique and exciting properties. MOFs have shown promise in many wide-ranging applications, such as catalysis and gas separations. In this review, we highlight MOF research conducted by Germany-based research groups. Specifically, we feature approaches for the synthesis of new MOFs, high-throughput MOF production, advanced characterization methods and examples of advanced functions and properties

Synthesis and Characterization of Covalent Triazine Framework CTF-1@Polysulfone Mixed Matrix Membranes and Their Gas Separation Studies

Covalent triazine framework CTF-1 and polysulfone (PSF) are used to form mixed-matrix membranes (MMMs) with 8, 16, and 24 wt% of the porous filler material CTF-1. Studies on permeability and selectivity are carried out concerning the gases O2, N2, CO2, and CH4. CO2 permeability of the synthesized MMMs increases by 5.4 Barrer in comparison to the pure PSF membrane. The selectivity remains unchanged for O2/N2 and CO2/CH4 but was found to be increased for CO2/N2. Further, comparisons to theoretical models for permeability prediction yield a permeability for CTF-1 which is about six times higher than the permeability of PSF. The inverse of the sum of the free fractional volumes (FFV) of the polymer and the filler correlate linearly to the logarithm of the permeabilities of the gases which conversely indicates that the porosity of the filler contributes to the gas transport through the membrane