Solvation cavity

Born radius for solvation cavities Summation indices for virtual MOs Expansion coefficients-----------------... 

The difference in the energy levels of a solvated electron in solution and of an electron in vacuum may be considered as solution-to-vacuum equilibrium electronic work function. The quantity — A may be considered as free energy of electron solvation (i.e. with the formation of solvated electrons) it relates to an equilibrium process. That is, in the initial state the electron is in the equilibrium solvate cavity while in the final state it is in vacuum, close to the solution surface, and the solvent is in its equilibrium disordered state (i.e. there is no solvate cavity in it). 

Crown ethers have also proven valuable in nucleophilic displacement reactions. The cations of potassium salts, such as KF, KCN, and KNj, are very tightly bound within the solvation cavity of 18-crown-6 molecules. The anions, however, are only weakly solvated, and because of the geometry of cation binding within the cavity of the crown, only loose ion pairing occurs between the anion and cation. Thus, in nonpolar aprotic solvents, these anions are without any appreciable solvent shell and, therefore, are highly reactive as nucleophiles. The nucleophili-city of F, CN , Nj , and other anions in nonpolar aprotic solvents containing an 18-crown-6 equals and often exceeds their nucleophilicity in polar aprotic solvents such as DMSO and acetonitrile. 

A hydrogen-bonded network of water molecules was predicted to fill a large cavity on the cytoplasmic side of Qb- This cavity, which we have named the methoxy pocket because of its proximity to the methoxy groups in Qb, contains water molecules that are closest to the Qb carbonyl oxygens (fig. 2B). Although the methoxy pocket is deeply buried in the RC, it is near another solvated cavity that is closer to the cytoplasm. The closest distance between the water molecules in the two pockets is 3.9 A. Both cavities are at the interface between the H-subunit and the L and M subunits. 

For cutoff distances > 3.9 A, pathways were formed from the methoxy pocket to another solvated cavity that is closer to the cytoplasm. One water molecule in this cavity is 3.3 A from the external surface. Thus, it is possible that proton transfer can occur from external solvent to the internal water molecules that are nearest to Qb (those in the methoxy pocket) via a chain consisting entirely of water molecules. 

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