Desolvate solvate

Solid compounds can have four morphic states polymorphic, pseudo-polymorphic (solvates), amorphous, and desolvated solvates. Crystals usually exhibit narrow melting point ranges and defract light under an optical microscope. When a change in the arrangement of... 

Figure 3.17 shows the DSC behaviour of the methanolate, the desolvated solvate and two polymorphs of the hydrochloride salt of a development compound. These thermograms are... 

A desolvated solvate is the species formed upon removal of the solvent from a solvate. Depending on the empirical details of the system, the desolvated solvate may be produced as either a crystalline or an amorphous phase. These materials are not equivalent, possessing different free energies, and the amorphous phase will ordinarily be the less stable... 

However, from a phase rule viewpoint, a completely desolvated solvate, from which the solvent vapor has been totally removed from the residual solid, is simply a system of one component. The characteristics and phase equilibria of such systems have been amply described earlier in Section II. All of the deductions reached about systems of one component must necessarily hold for solids produced by the desolvation of a solvate species. 

But of eourse, there are drawbaeks in using solvents. Beeause there are not totally inert they may favor the formation of undesirable impurities in the intermediates of synthesis and in the DS. Regarding the manufaeture of the DP, the solvents, ineluding water, may induee either polymorphie transformations or formation of solvates (hydrates) whieh, after drying, eould lead to a desolvated solvate with quite different physieal properties impaeting potentially either positively or negatively on the DP performanee. ... 

The solvate is poorly stable and the solvent is easily removed leading to either the original polymorphic form but creating a certain degree of disorder in the crystalline structure or to what is called a desolvate solvate form. In this last case, also named isomorphic desolvate , the desolvated solvate retains the structure of its parent solvated form. The X-ray diffraction patterns look similar between the parent and the daughter forms. In this situation we have the creation of a molecular vacuum which could substantially impact on the stability, hygroscopicity and mechanical characteristics of the DS and finally of the DP. 

Solvents bound to drug moleeules in the erystal lattiee. These solvents present as solvates (hydrates) are lost at a eharaeteristie temperature and may be stable only over a limited range of relative humidity. The solvates and desolvated solvates, whilst being two different ehemieal entities, ean retain the same erystalline strueture (similarity of x-ray diffraetion pattern) but show different physieo-ehemieal properties. 

When complexing the ligand with the lanthanide ion, many processes occur, including desolvation/solvation processes and successive formation of intermediate species Lanthanides Coordination Chemistry). In most cases, the complex is formed within seconds, with some exceptions such as l,4,7,10-tetraazacyclododecane-l,4,7,10-tetraacetic acid (DOTA) complexes. In the latter, the reaction is very slow and the equilibrium will take several days to establish. As a consequence, at room temperature, the solution will be stirred for more than 5 days, whereas on gentle warming of the solution, the delay can be reduced to half (this is the golden rule in kinetics on increasing the reaction fl om room temperature to 10 °C more, the rate should be increased by approximately a factor of two). 

The best and safest way to prepare the seeds is to disperse them in the same solvent as used in the crystallizer. This dispersion can be achieved by sonication or high-shear mixing. Dispersing seeds has some more advantages very fine material from the milling may be dissolved, distorted lattices may heal, amorph-ized surfaces may recrystallize, and desolvated solvates (during drying of the seed... 

The cooperativity between the collapse/swelling and the desolvation/solvation of the PNIPAM brushes can be viewed by the relation of AD versus Af. Figure 2.10 shows that AD linearly decreases as A/increases, suggesting that the... 

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