Synthesis, Infra-red, Raman, NMR and structural characterization by X-ray Diffraction of [C12H17N2]2CdCl4 and [C6H10N2]2Cd3Cl10 compounds

The synthesis, infra-red, Raman and NMR spectra and crystal structure of 2, 4, 4- trimethyl-4, 5- dihydro-3H-benzo[b] [1, 4] diazepin-1-ium tetrachlorocadmate, [C12H17N2]2CdCl4 and benzene-1,2-diaminium decachlorotricadmate(II) [C6H10N2]2Cd3Cl10 are reported. The [C12H17N2]2CdCl4 compound crystallizes in the triclinic system (P-1 space group) with Z = 2 and the following unit cell dimensions: a = 9.6653(8) angstrom, b = 9.9081(9) angstrom, c = 15.3737(2) angstrom, alpha = 79.486(1)degrees, beta = 88.610(8)degrees and gamma = 77.550(7)degrees. The structure was solved by using 4439 independent reflections down to R value of 0.029. In crystal structure, the tetrachlorocadmiate anion is connected to two organic cations through N-H...Cl hydrogen bonds and Van Der Waals interaction as to build cation-anion-cation cohesion. The [C6H10N2]2Cd3Cl10 crystallizes in the triclinic system (P-1 space group). The unit cell dimensions are a = 6.826 (5)angstrom, b = 9.861 (7)angstrom, c = 10.344 (3)angstrom, alpha = 103.50 (1)degrees, beta = 96.34 (4)degrees and gamma = 109.45 (3)degrees, Z=2. The final R value is 0.053 (Rw=0.128). Its crystal structure consists of organic cations and polymeric chains of [Cd3Cl10]4- anions running along the [011] direction, In The [C6H10N2]2Cd3Cl10 compounds hydrogen bond interactions between the inorganic chains and the organic cations, contribute to the crystal packing. PACS Codes: 61.10.Nz, 61.18.Fs, 78.30.-jComment: 19 pages, 10 figure

Mapping the working route of phosphate monoester hydrolysis catalyzed by copper based models with special emphasis on the role of oxoanions by experimental and theoretical studies

Three copper(II) complexes derived from a reduced Schiff base ligand namely 4-bromo-2-[(2-hydroxy-1,1-dimethyl-ethylamino)-methyl]-phenol (H2L) were prepared by varying oxoanions (ClO4 12, NO3 12, OAc 12) to explore the influence of anions on phosphatase activity and to explore the mechanistic pathway. Amongst the three complexes, complex 1 ([Cu4(L)2(HL)2(ClO4)2]\ub7CH3OH) was reported earlier by us, whereas 2 ([Cu4(L)2(HL)2(NO3)2\ub7C2H5OH\ub70.5H2O]) and 3 ([Cu4(L)2(HL)2 (OAc)2]\ub7CH3CN\ub7H2O) have been newly synthesized and structurally characterized by single crystal X-ray diffraction. The solution phase structure of the three complexes was determined by an ESI-MS technique. All the complexes (as dinuclear species) were able to hydrolyze the phosphate ester bond of 4-nitrophenylphosphate in a 97.5% N,N-dimethylformamide (DMF) medium and the rate of hydrolysis follows the trend 1 > 2 > 3. The intermediates formed during the reaction process were identified by means of ESI-MS study using the reaction mixture of complexes 1, 2 and 3. The detailed mechanistic pathway and role of oxoanions have been evaluated with the help of DFT calculations. The mechanism proposed for phosphatase activity by considering a dicopper complex without any oxoanion indicates the attack of the hydroxo ligand to the phosphate monoester as the rate-limiting step. The intermediates that were trapped experimentally match closely with the models proposed for the theoretical calculations. The extensive theoretical approach using a total of 36 model complexes and two possible mechanistic pathways proved that the presence of the oxoanion accelerates the hydrolysis of the phosphate ester bond and among the complexes studied the hydrolysis by the ClO4 12 derivative appears to be the most active

Distribution and mobility of geogenic arsenic in the shallow aquifers of the northeast of La Pampa, Argentina

Groundwater contamination with elevated arsenic (As) and other toxic trace elements has been studied in the central part of the vast Chaco-Pampean Plain, in the city of Quemu Quemu, northeastern La Pampa, Argentina. The groundwater samples were mostly alkaline with pH ranging up to 9.18, oxidizing and characterized by high EC. The concentration of total As (5.58-535 µg/L) and fluoride (0.5-14.2 mg/L) in some samples exceeded the recommended WHO drinking water guideline and the Argentine national drinking water standard. Arsenic was positively correlated with HCO3-, F-, B and V. Long-term consumption of the groundwater could pose a severe health threat for the local community