Co-solvation

The layered phosphonates of zirconium, Zr(03PCH2CH2C00H)2, and vanadium, V0(03PCH2CH2C00H)2, were prepared by following Dine s (reaction 1) and Jacobson and Johnson s (reaction 2) procedures, respectively, with X = P and R = CH2CH2COOH. For the vanadium system, we get the interdigitated material shown in Figure 6, where a chain assumes a trans conformation, directed toward an alcohol co-solvate (which occupies... 

Figure 6. Schematic representation of V0(03PCH2CH2C00H) prepared by reaction 2. Pendant phosphonates, which are directed into the layer in a gauche conformation, are (a) interdigitated when the alcohol co-solvate (indicated by shaded rectangles) is < 3 carbons and (b) in a head-to-tail conformation for > 3 carbons. The d-spacings for the MeOH, EtOH, PrOH, BuOH, and BzOH materials are 13.8, 14.8, 16.4, 18.2, and 18.6 A, respectively.

The situation may become even more challenging when the phase diagram exhibits a highly non-ideal shape as a result of strong attractive interactions in solution (co-solvation). As can be seen from Figure 12.9, the strategy of adding the solid material of one component to a saturated solution of the second may... 

In real systems, the effect may not always be as pronounced as this. In particular, a co-solvating effect of the co-crystal former may weaken or even reverse the consequences of the solubility product on yields. Such effects are particularly likely to occur when ionic interactions between components prevail in solution (e.g., as a result of proton transfer). For systems that do not deviate too far from ideality, it can be stated that the eoneentration of the co-crystal former should be chosen as high as possible in order to increase... 

One was an investigation of CO solvated in small helium clusters, for cluster sizes (N) up to 30 [43]. Here binding energies were calculated and related to the... 

Another publication considered the rotational spectrum of CO solvated in para — (H2)a/ clusters, for cluster sizes (N) 2-17 [46]. Here R 0) transitions and their spectral weights were assigned up to A = 9 for -type series (free molecule rotations) and A = 14 for a-type series (end-over-end rotations). As was the case for CO-Hejv, there was a decreasing tendency of the hydrogen molecules to dynamically cluster on one side of the CO molecular axis as completion of the first solvation shell was approached. Theory and experiment agreed well, except that theory tended to overestimate the -type energies. 

The final class of methods that we shall consider for calculating the electrostatic compone of the solvation free energy are based upon the Poisson or the Poisson-Boltzmann equatior Ihese methods have been particularly useful for investigating the electrostatic properties biological macromolecules such as proteins and DNA. The solute is treated as a body of co stant low dielectric (usually between 2 and 4), and the solvent is modelled as a continuum high dielectric. The Poisson equation relates the variation in the potential (f> within a mediu of uniform dielectric constant e to the charge density p ... 

The water of hydration of these complexes can be replaced with other coordinating solvents. For example, the ethanol and methanol solvates were made by dissolving the hydrates in triethyl and trimethyl orthoformate, respectively (81,82). The acetic acid solvates are made by treating the hydrates with acetic anhydride (83). Conductivity and visible spectra, where appHcable, of the Co, Ni, Zn, and Cu fluoroborates in A/A/-dimethylacetamide (L) showed that all metal ions were present as the MLg cations (84). Solvated fluoroborate complexes of, Fe +, Co +, , Cu +, and in diethyl... 

The crown ethers and cryptates are able to complex the alkaU metals very strongly (38). AppHcations of these agents depend on the appreciable solubihty of the chelates in a wide range of solvents and the increase in activity of the co-anion in nonaqueous systems. For example, potassium hydroxide or permanganate can be solubiHzed in benzene [71 -43-2] hy dicyclohexano-[18]-crown-6 [16069-36-6]. In nonpolar solvents the anions are neither extensively solvated nor strongly paired with the complexed cation, and they behave as naked or bare anions with enhanced activity. Small amounts of the macrocycHc compounds can serve as phase-transfer agents, and they may be more effective than tetrabutylammonium ion for the purpose. The cost of these macrocycHc agents limits industrial use. 

In a series of papers published throughout the 1980s, Colin Poole and his co-workers investigated the solvation properties of a wide range of alkylammonium and, to a lesser extent, phosphonium salts. Parameters such as McReynolds phase constants were calculated by using the ionic liquids as stationary phases for gas chromatography and analysis of the retention of a variety of probe compounds. However, these analyses were found to be unsatisfactory and were abandoned in favour of an analysis that used Abraham s solvation parameter model [5]. 

The solubility of Ag(CN)2"in water stems from the overall negative charge encouraging solvation with water dipoles, which uncharged AgCN does not. It is likely that the other cyanide complex ions of low co-ordination number have a similar structure. 

Apart from reactions with the electrolyte at the carbon surface, the irreversible specific charge is furthermore strongly affected by the possible co-intercalation of polar solvent molecules between the graphene layers of highly graphitic matrices [139]. This so-called "solvated intercalation reaction" depends (i) on the crystallinity and the morphology of the parent carbonaceous material, which will be discussed in Sec. 

Furthermore, the molecular size of the Li+ -solvating solvents may affect the tendency for solvent co-intercalation. Crown ethers [19, 152-154, 196, 197] and other bulky electrolyte additives [196] are assumed to coordinate Li+ ions in solution in such a way that solvent co-intercalation is suppressed. The electrochemical formation of binary lithiated graphites Li tC6 was also reported for the reduction... 

The smaller ion may intercalate faster into the graphite galleries. Reaction (5) may be the rate-determining step for the solvent co-intercalation process, and if so, molecules that form large and stable solvated lithium cations will have a smaller tendency for co-intercalation into the graphite. 

A further important feature of HMPA is its stabilizing effect on the Redox potential of [Fe(CO)4]2 by ion solvation. In less polar solvents, electron-transfer reactions take place and [Fe(CO)4]2 is oxidized to [HFe3(CO)iThis redox reaction is suppressed in HMPA. 

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