Ion Pair Formation in Solutions of Alkali Halides in Dimethyl Sulfoxide: Ultrasonic Absorption Studies

1971 ◽  
Vol 49 (19) ◽  
pp. 3107-3113 ◽  
Author(s):  
D. R. Dickson ◽  
P. Kruus
Keyword(s):  
Dimethyl Sulfoxide ◽  
Solvent Molecule ◽  
Alkali Halides ◽  
Ion Pair ◽  
Ultrasonic Absorption ◽  
Absorption Studies ◽  
System Water ◽  
Excess Absorption ◽  
Stepwise Formation ◽  
Rate Of Movement

The ultrasonic absorption of dimethyl sulfoxide solutions of several alkali halides has been studied in the frequency range 1.5 to 52 MHz. An excess absorption, relaxing between 3 and 8 MHz, was observed. The relaxation was assigned to the final step in the stepwise formation of a contact ion pair, with the relaxation frequency controlled by the rate of movement of a solvent molecule rather than an ion. Data on the system water – dimethyl sulfoxide are also presented and the effect of water on the relaxation discussed.

Ion Pair Formation and Solvation Energies in Solutions of Alkali Halides in Dimethyl Sulfoxide. II. Model Calculations

1975 ◽  
Vol 53 (7) ◽  
pp. 1007-1018 ◽  
Author(s):  
Merrill S. Goldenberg ◽  
Peeter Kruus ◽  
Stephen K. F. Luk
Keyword(s):  
Dimethyl Sulfoxide ◽  
Electrostatic Interactions ◽  
Minimum Energy ◽  
Alkali Halides ◽  
Dmso Molecule ◽  
Ion Pair ◽  
Model Calculations ◽  
Energy Calculations ◽  
Solvation Energies ◽  
Repulsive Forces

Energy calculations were carried out on models of molecular-level structures likely to be present in solutions of alkali halides in dimethyl sulfoxide (DMSO). Classical electrostatic interactions were assumed, and polarization of a DMSO molecule was assumed due to the fields of the ions only. The validity of this assumption was tested. DMSO molecules were represented by increasingly detailed models, with most calculations carried out with each molecule represented by 10 point charges and 9 polarizable bonds. A program including up to 14 such molecules and two ions was used for energy and distance calculations, and is made available. Polarization effects are as important as interactions between permanent charges for energy calculations. The configurations of minimum energy determined by classical electrostatics often do not involve overlap of the "hard-sphere radii" of neighboring species, so that the neglect of quantum mechanical repulsive forces seems justified. Energy cycles using the calculated energies for ion–solvent complexes predicted experimental cation enthalpies with some success. The form of the potential for vibration of a cation in a solvent shell was investigated and found in cases not to have an energy minimum at the shell center. Calculations including next-nearest solvating DMSO's indicate a rather loose structure. An energy profile for an anion moving from a solvent-separated ion pair position to a contact-ion pair position is presented.

Ion association in solutions of HCl in DMSO–water mixtures: ultrasonic absorption studies

1978 ◽  
Vol 56 (14) ◽  
pp. 1881-1888
Author(s):  
Peeter Kruus ◽  
M. Jacqueline Mcguire
Keyword(s):  
Equilibrium Constants ◽  
Ion Association ◽  
Rate Theory ◽  
Ultrasonic Absorption ◽  
Relaxation Equation ◽  
A Value ◽  
Diffusion Controlled ◽  
Absorption Studies ◽  
Excess Absorption ◽  
Absorption Measurements

Ultrasonic absorption measurements are reported for the System HCl–dimethylsulfoxide (DMSO)–water in the frequency range 3.5 to 140 MHz. For ail solutions studied, the excess absorption due to the presence of HCl can be fitted well with a single relaxation equation. For 0.10 mol ℓ−1 solutions of HCl in DMSO–water mixtures, no further relaxations at higher frequencies are likely. Reasonable results are obtained when the ultrasonic results are analyzed assuming the process responsible for the excess absorption to be the dissociation–association equilibrium of HCl, and using equilibrium constants determined from conductivity (C. Cooke etal. Electrochim. Acta, 20, 591 (1975)). The value of |ΔVeff| is 20–25 cm3 mol−1 and Kass is approximately 3 × 109ℓ mol−1 s−1, as compared to a value of 10 × 109ℓ mol−1 s−1 calculated from limiting conductivities assuming diffusion-controlled rate theory.

Novel pseudopolymorph of the active metabolite of perindopril

2012 ◽  
Vol 68 (9) ◽  
pp. o341-o343 ◽  
Author(s):  
Joanna Bojarska ◽  
Waldemar Maniukiewicz ◽  
Lesław Sieroń ◽  
Andrzej Fruziński ◽  
Piotr Kopczacki ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Dimethyl Sulfoxide ◽  
Active Metabolite ◽  
Alkyl Chain ◽  
Solvent Molecule ◽  
Carboxylate Group ◽  
X Ray Diffraction ◽  
Structural Units ◽  
X Ray ◽  
Zwitterionic Form

The dimethyl sulfoxide hemisolvate of perindoprilat [systematic name: (1S)-2-((S)-{1-[(2S,3aS,7aS)-2-carboxyoctahydro-1H-indol-1-yl]-1-oxopropan-2-yl}azaniumyl)pentanoate dimethyl sulfoxide hemisolvate], C17H28N2O5·0.5C2H6OS, an active metabolite of perindopril, has been synthesized, structurally characterized by single-crystal X-ray diffraction and compared with its ethanol disolvate analogue [Pascardet al.(1991).J. Med. Chem.34, 663–669]. Both compounds crystallize in the orthorhombicP212121space group in the same zwitterionic form, with a protonated alanine N atom and an anionic carboxylate group at then-alkyl chain. The three structural units present in the unit cell (two zwitterions and the solvent molecule) are held together by a rich system of O—H...O, N—H...O and C—H...O hydrogen-bond contacts.

Modelling of interactions in solutions: alkali halides in DMSO

1979 ◽  
Vol 57 (5) ◽  
pp. 538-551 ◽  
Author(s):  
Peeter Kruus ◽  
Barbara E. Poppe
Keyword(s):  
Reasonable Agreement ◽  
Minimum Energy ◽  
Alkali Halides ◽  
Ion Pair ◽  
Point Of View ◽  
Ion Solvation ◽  
Solvation Energies ◽  
Solvent Molecules ◽  
A Charge ◽  
Energy Configurations

A model of solutions of alkali halides in DMSO is developed. Each ion is described by a radius, a charge, a polarizability, and an exponential repulsion parameter. Each molecule is described by a polarizability, charges, 6-12 energy parameters, and 6-12 distance parameters centered on each of the 10 atoms in the molecule. The model is applied to calculate (i) the vaporization energy of solvent molecules, (ii) single ion solvation energies and configurations of the solvating molecules, and (iii) the energy as a function of reaction coordinate for the formation of an ion pair. The energies and configurations are obtained by allowing the systems to relax to minimum energy configurations by allowing motion of the molecules. The results of (i) give a vaporization energy 60% of the experimental. The results of (ii) give solvation energies in reasonable agreement with the experimental, and configurations which are reasonable from the point of view of mobilities of ions. The results of (iii) show the presence of a distinct solvent separated ion pair which actually has an energy lower than the contact ion pair. Advantages and problems involved in using this approach to model solutions are discussed.

scholarly journals Pyrimethaminium 2-{[4-(trifluoromethyl)phenyl]sulfanyl}benzoate dimethyl sulfoxide monosolvate

2014 ◽  
Vol 70 (6) ◽  
pp. o683-o684 ◽  
Author(s):  
Thammarse S. Yamuna ◽  
Manpreet Kaur ◽  
Jerry P. Jasinski ◽  
H.S. Yathirajan
Keyword(s):  
Hydrogen Bonds ◽  
Dimethyl Sulfoxide ◽  
Dihedral Angle ◽  
Solvent Molecule ◽  
Three Dimensional ◽  
Dimensional Network ◽  
Benzene Rings ◽  
Graph Set ◽  
Molecular Salt

In the cation of the title solvated molecular salt, C12H14ClN4+·C14H8F3O2S−·C2H6OS [systematic name of the cation: 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium], the dihedral angle between the planes of the pyrimidinium and 4-chlorophenyl rings is 77.2 (5)°. In the anion, the planes of the benzene rings are twisted with respect to each other by 71.5 (5)°. Disorder was modelled for the dimethyl sulfoxide solvent molecule over two set of sites in a 0.7487 (13):0.2513 (13) ratio. In the crystal, the cations are linked by inversion-generated pairs of N—H...N hydrogen bonds, with anR22(8) graph-set motif. The cation donates two N—H...O hydrogen bonds to the anion, also generating anR22(8) loop. These interactions, along with cation–solvent N—H...O hydrogen bonds, and cation–anion C—H...F, solvent–anion C—H...O and C—H...F interactions, result in a three-dimensional network.

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