Crystallization and characterization of magnesium methanesulfonate hydrate Mg(CH3SO3)2•12H2O

Records of methanesulfonate acid in ice cores play an important role in reconstruction of the past history of marine productivity, sea ice extent, and major El Ni~no event activities related to climate changes. Considering the lack of thermodynamic and crystal structure data, crystallization conditions below zero degrees Celsius were mimicked in the laboratory, and magnesium methanesulfonic hydrate crystals, Mg(CH3SO3)2 3 12H2O(i.e., [Mg(H2O)6](CH3SO3)2 3 6H2O) were grown from solution by cooling crystallization and by eutectic freeze crystallization. The solubility lines between-5 andþ21 C and between 0 and 25 wt%are presented. The eutectic point of the system is detected at-5 Cand 14 wt %. The crystal structure analysis and the molecular arrangement of these crystals were determined using single crystal X-ray diffraction (XRD). Reflections were measured at a temperature of 110(2) K. The structure is trigonal with space group R3 (no. 148). The crystal is a colorless block with the following parameters: a=b=9.27150(8)A ° , c=21.1298(4)A ° , V=1572.99(4)A ° 3, Z=3, andDcalc= 1.364 g/cm3. The Raman spectrum of Mg(CH3SO3)2 3 12H2O salt has been recorded and the principal absorption modes identified. Thermogravimetric analysis confirmed the stochiometry of the Mg(CH3SO3)2 3 12H2O salt

Crystal structure, stability, and electronic properties of hydrated metal sulfates MSO4(H2O)(n) (M=Ni, Mg; n=6, 7) and their mixed phases : A first principles study

Removal of Mg from hydrated Ni sulfates has long been a problem in the industrial purification process of hydrated Ni sulfates. In this work, we have investigated this industrial problem using state-of-the-art molecular simulations. Periodic Density Functional Theory (DFT) and cluster DFT calculations are used to study the crystal structures and phase stability of the hexahydrated and heptahydrated Ni and Mg sulfates and their mixed phases. The calculated lattice parameters of MSO4(H2O)(n) (M=Ni, Mg; n=6, 7) crystals are in good agreement with available experimental data. The relative energy differences of the mixed phase for both hexahydrated and heptahydrated Ni/Mg sulfates obtained from both the periodic and cluster DFT calculations are generally less than kT (25.8 meV, T=300 K), indicating that a continuous solid solution is formed. We also investigated the Bader charges and electronic structures of the hexahydrated and heptahydrated Ni/Mg sulfates using the periodic DFT calculations. The energy band gaps of the hexahydrated and heptahydrated Ni and Mg sulfates were predicted by first-principles calculations. Large energy band gaps of about similar to 5.5 eV were obtained from the DFT-GGA calculations for hydrated Mg sulfates, and band gaps of about similar to 5.1 eV were obtained by the DFT-GGA+U calculations for hydrated Ni sulfates. (C) 2014 Elsevier Ltd. All rights reserved

Theoretical Investigation Of The Anti-Parkinson Drug Rasagiline And Its Salts: Conformations And Infrared Spectra

The conformational analysis of rasagiline [N-propargyl-1(R)-aminoindan] was performed by the density functional theory (DFT) B3LYP method using the 6-31++G (d,p) basis set. A single point energy calculations based on the B3LYP optimized geometries were also performed at MP2/6-31++G (d, p) level. The vibrational frequencies of the most stable conformer of rasagiline was calculated at the B3LYP level and vibrational assignments were made for normal modes on the basis of scaled quantum mechanical force field (SQM) method. The influence of mesylate and ethanedisulfonate salts on the geometry of rasagiline free base and its normal modes are also discussed.WoSScopu