Solvation categorization

In this section, we switch gears slightly to address another contemporary topic, solvation dynamics coupled into the ESPT reaction. One relevant, important issue of current interest is the ESPT coupled excited-state charge transfer (ESCT) reaction. Seminal theoretical approaches applied by Hynes and coworkers revealed the key features, with descriptions of dynamics and electronic structures of non-adiabatic [119, 120] and adiabatic [121-123] proton transfer reactions. The most recent theoretical advancement has incorporated both solvent reorganization and proton tunneling and made the framework similar to electron transfer reaction, [119-126] such that the proton transfer rate kpt can be categorized into two regimes (a) For nonadiabatic limit [120] ... 

More restrictive assumption is the binding mode in a ligand-receptor complex which categorically designates the maximal position of the ligand in an assymetric force produced by the respective receptor which is duly exposed to the suitable entropic considerations and the ensuing perturbation due to solvation. 

For this chapter, the word form is used to refer to any solid made from the molecule, including polymorphs, solvates, hydrates, and even amorphous solids. In the initial solid-state studies, the precise physical state (polymorph, solvate, etc.) of the drug is generally unknown. In fact, it may require a great deal of time and effort to establish whether or not a solid is a hydrate and how many water molecules exist in the crystal lattice. It is convenient at this stage to categorize all solids forms. Somehmes the word modification is employed for the same... 

Explicit-Solvent versus Continuum-Solvent Methods. Theoretical treatments of solvation can be categorized as either explicit-solvent approaches, in which many individual solvent molecules are explicitly included, or as continuum-solvent methods, where the solvent molecules are replaced by a continuous dielectric (Section 15.22). 

Research workers investigating the solvent effect selected model systems with some well measurable property (e.g., light absorption in the UV, visible or IR spectrum, heat of formation, an NMR, Mossbauer or NQR parameter, the redox potential, reaction rate, etc.) which changes appreciably due to the effect of the solvent. Hence, these experimentally measurable data, characteristic of the extent of the interaction between the solvent and the solute, may serve to categorize the solvating powers of solvents. Of course, solvent scales obtained in this way can be compared with one another only if the solvation process in the different model systems is governed by analogous factors. 

Other enthalpic interactions depend on the chemical nature of the species being solvated. For example, solvents that can act as electron-pair donors (Lewis bases) can undergo specific interactions with metal cations that are electron-pair acceptors (Lewis acids). Notably, the transition metals may act as Lewis acids due to their unfilled d-orbitals the specific nature of the interaction depends on the particular coordination characteristics of the metal ion. Lewis acid-base interactions are categorized as specific chemical. 

Co-crystals are nothing other than intermediate compounds. Thus, the term might only be justified by the nature of the bonds connecting the partners that constitute the crystal. Nevertheless, the concept suffers from intrinsic uncertainties due to the numerous, difficult to categorize, situations in which they can occur, such as the continuum between solvate and co-crystals, hybrid salt-cocrystals, multi-epitaxy and so on. It is even possible to find the same partners with simultaneously salt-like and co-crystal-like relationships in a given crystal structure. ... 

In general, theories of solvation can be categorized according to the criteria discussed below. 

As described above, many electrolytes for lithium-ion batteries are based on mixed solvent systems, which can overcome some drawbacks of a single solvent system. When the lithium salt concentration is high, the ionic conductivity behavior can be categorized as contact ion pairs, solvent separated ion pairs, and fully solvated ion pairs. In mixed solvents, the solvent composition influences the dielectric constant and ion pair structure. The D.N. and A.N. of the solvent and the charge density of the ions also influence ion pair formation. Equations 9.2 and 9.3 describe the competition between the contact ion pair and solvent separated ion pair models ... 

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