Incorporation of solvent effects

Perez, C., Pastor, M., Ortiz, A.R., and Gago, F. Comparative binding energy analysis of HIV-1 protease inhibitors incorporation of solvent effects and validation as a powerful tool in receptor-based drug design. /. Med. Chem. 1998, 41, 836-852. 

Incorporation of Solvent Effects in Crystal Habit Calculations... 

O. Takahashi, H. Sawahata, Y. Ogawa and O. Kikuchi, Incorporation of solvent effects into ab initio molecular orbital calculations by the generalized Born formula. Formulation, parameterization, and applications, J. Mol. Struct. (THEOCHEM), 393 (1997) 141-150. 

Andzelm, J., Kolmel, C., Klamt, A. Incorporation of solvent effects into density-functional calculations of molecular energies and geometries. J. Chem. Phys. 1995,103(21), 9312-20. 

In summary, while 3D structure searching is now a mature technology, it still is in its infancy with respect to many potential growth areas, including improvements in post-search processing and hit list prioritization/management, incorporation of solvent effects, fuzzy and unified steric-electronic queries, and receptor-based 3D searching. 

J. Andzehn, Ch. Kolmel and A. Klamt. Incorporation of solvent effects into density... 

During continuous redox cycling, the first cycle usually differs from the following ones. This effect is referred as break-in. In poly(vinylferrocene), PVF, films this has been related to the incorporation of solvent and ions into the film, decreasing its resistivity [132]. This effect has been observed for several polyelectrolyte and polymer-modified electrodes, for example, polyaniline [155]. 

The above-mentioned type of solvent effects has been incorporated into the theory of helix-coil transition by a number of authors (7,24,36 38), with various types of reactions being assumed. These theories explain why AH becomes temperature-dependent in inverse helix-coil transitions and also permit an estimate of AH in pure helicogenic solvents. Their details are surveyed in our companion review article (11). 

By contrast, when both the reactive solute molecules are of a size similar to or smaller than the solvent molecules, reaction cannot be described satisfactorily by Langevin, Fokker—Planck or diffusion equation analysis. Recently, theories of chemical reaction in solution have been developed by several groups. Those of Kapral and co-workers [37, 285, 286] use the kinetic theory of liquids to treat solute and solvent molecules as hard spheres, but on an equal basis (see Chap. 12). While this approach in its simplest approximation leads to an identical result to that of Smoluchowski, it is relatively straightforward to include more details of molecular motion. Furthermore, re-encounter events can be discussed very much more satisfactorily because the motion of both reactants and also the surrounding solvent is followed. An unreactive collision between reactant molecules necessarily leads to a correlation in the motion of both reactants. Even after collision with solvent molecules, some correlation of motion between reactants remains. Subsequent encounters between reactants are more or less probable than predicted by a random walk model (loss of correlation on each jump) and so reaction rates may be expected to depart from those predicted by the Smoluchowski analysis. Furthermore, such analysis based on the kinetic theory of liquids leads to both an easy incorporation of competitive effects (see Sect. 2.3 and Chap. 9, Sect. 5) and back reaction (see Sect. 3.3). Cukier et al. have found that to include hydrodynamic repulsion in a kinetic theory analysis is a much more difficult task [454]. 

In view of these recent studies, it appears that (1) incorporation of solvent molecules into the lattice of the Fe(R2Dtc)3 complexes can be as effective as temperature or pressure changes in shifting the spin-state equilibria, and (2) some of the magnetic data in the literature on the Fe(R2 Dtc)3 complexes may well be misleading owing to the presence of different types and quantities of solvents in the lattice. 

The requirement needed to incorporate the solvent effects into a state-specific (multireference) method is fulfilled by using the effective Hamiltonian defined in Equation (1.159). The only specificity to take into account is that in order to calculate Va we have to know the density matrix of the electronic state of interest (see the contribution by Cammi for more details). Such nonlinear character of Va is generally solved through an iterative procedure [35] at each iteration the solvent-induced component of the effective Hamiltonian is computed by exploiting Equation (1.157) with the apparent charges determined from the standard ASC equation with the first order density matrix of the preceding step. At each iteration n the free energy of each state K is obtained as... 

In this framework, the requirement needed in order to incorporate the solvent effects into the reactant (and product) wavefunctions is automatically fulfilled by using the effective Hamiltonian defined in Equation (3.155) and by adopting an iterative procedure until the wave-function and the solvent reaction field induced by the Cl density matrix of the state of interest reach self-consistency. One must note that this procedure is valid for ground and excited states fully equilibrated with the solvent, while the inclusion of nonequilibrium effects needs some further refinements, as indicated, for example, in ref. [35],... 

Combination of Eqs. 33-36 with Eqs. 37 and 38 gives the following final angular dependences, which incorporate the solvent effect ... 

The Records Conservation Section has five years of satisfactory experience treating a variety of unique works with Wei To solutions. A survey of conservators and scientists in other institutions verified the chemistry was sound and the results were aesthetically acceptable. The problems to be resolved were mechanical, involving equipment choice rather than the chemistry of the treatment (11). The hazards inherent to the system could be isolated and controlled at the treatment site. The solvent, approximately 90% dichlorodifluoromethane and 10% methanol by volume, has a maximum allowable concentration of 982 ppm in air (12), a level many times more than expected in workroom air. Incorporation of solvent recovery equipment not only reduces unit treatment cost but avoids a potential detrimental effect on the ozone layer in the upper atmosphere by dichlorodifluoromethane. 

The reduction of camphor enamines by the same method has been found to be highly selective, leading to the endo isomer as the predominant product (85-87%)204 (Scheme 136). The lack of solvent effect and the incorporation of up to 3 deuterium atoms when using DCOOD, are in favour of a two-step mechanism. This would involve reversible protonation of the / -carbon atom with formation of the iminium ion, followed by irreversible transfer of hydride from the formate ion to this ion. 

An illustrative example of solvent effects on absorption and emission spectra is given by the following positive solvatochromic laser dye 7-dialkylamino-4-(trifiuoromethyl)coumarin ( coumarin-153 ), in which the rotation of an amino group is restricted by incorporating it into a hexahydroquinolizine ring [341],... 

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