Solvent surface area

Table 1. Grafting of 3-aminopropyl groups on mesoporous silica obtained in polar-protic, polar-aprotic and non-polar solvents, surface area and catalytic efficiency for Nitroaldol condensation of 4-hydroxybenzaldehyde and nitromethane [22]. 

In the paper entitled A remarkable effect of solvent size on the stability of a molecular complex , a strong correlation was shown between binding energy and surface area of the solvent molecule [61]. This study compared closely related families of solvents to determine the effect of solvent surface area on complex formation. Correlation was also shown between binding energy and solvation energies for the complexation of two families of solvents. It was proposed that the increase in solvation energy (positive values) that occurs as solvent size increases makes it thermodynamically favourable... 

The MEP at the molecular surface has been used for many QSAR and QSPR applications. Quantum mechanically calculated MEPs are more detailed and accurate at the important areas of the surface than those derived from net atomic charges and are therefore usually preferable [Ij. However, any of the techniques based on MEPs calculated from net atomic charges can be used for full quantum mechanical calculations, and vice versa. The best-known descriptors based on the statistics of the MEP at the molecular surface are those introduced by Murray and Politzer [44]. These were originally formulated for DFT calculations using an isodensity surface. They have also been used very extensively with semi-empirical MO techniques and solvent-accessible surfaces [1, 2]. The charged polar surface area (CPSA) descriptors proposed by Stanton and Jurs [45] are also based on charges derived from semi-empirical MO calculations. 

SASA Solvent-Accessible Surface Area Q . Average of absolule alomic charges... 

The nature of soliite-solnte and solute-solvent in teraction s is dependent on the solvent environment. Solvent influences the hydrogen-bon ding pattern, solute surface area, and hydrophilic and hydrophobic group exposures. 

Richmond T J 1984. Solvent Accessible Surface Area and Excluded Volume in Proteins. Journal oj Molecular Biology 178 63-88. 

Hasel W, T F Hendrickson and W C Still 1988. A Rapid Approximation to the Solvent Accessibh Surface Areas of Atoms. Tetrahedron Computer hAethodology 1 103-116. 

We conclude that the beneficial effects of water are not necessarily limited to reactions that are characterised by a negative volume of activation. We infer that, apart from the retro Diels-Alder reaction also other reactions, in which no significant reduction or perhaps even an increase of solvent accessible surface area takes place, can be accelerated by water. A reduction of the nonpolar nature during the activation process is a prerequisite in these cases. 

The solvent accessible surface area (SASA) method is built around the assumption that the greatest amount of interaction with the solvent is in the area very close to the solute molecule. This is accounted for by determining a surface area for each atom or group of atoms that is in contact with the solvent. The free energy of solvation AG° is then computed by... 

SAMI (semi-nh initio method one) a semiempirical method SASA (solvent-accessible surface area) algorithm for computing solvation elfects... 

A second form of desolvation chamber relies on diffusion of small vapor molecules through pores in a Teflon membrane in preference to the much larger droplets (molecular agglomerations), which are held back. These devices have proved popular with thermospray and ultrasonic nebulizers, both of which produce large quantities of solvent and droplets in a short space of time. Bundles of heated hollow polyimide or Naflon fibers have been introduced as short, high-surface-area membranes for efficient desolvation. 

As the droplets pass through the evaporation region, solvent evaporates, and the droplets rapidly become much smaller. At the same time, because the surface area of the droplets gets smaller and smaller, the density of electrical charge on the surface increases until a point of instability is reached. 

Paraffin wax vapor barriers are used in water rinse removers that can disperse the wax without coating the substrate. In soak tank applications, water is sometimes doated on top of an ad-solvent, neutral pH, nonwater rinse remover to prevent evaporation. Flotation devices that cover the exposed surface area may be used with other formulas. 

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