Desolvations of Solvated Organic Crystals

Solid state characterization of mometasone furoate anhydrous and monohydrate forms

“…It can be classified as a channel hydrate. 10 Similar structural characteristics are also present in crystals of ampicillin trihydrate, 11 caffeine hydrate, 12 theophylline hydrate, 13 and thymine hydrate. 14 Each water molecule forms three hydrogen bonds with neighboring mometasone furoate molecules in the crystal structure as listed in Table 3 and illustrated in Scheme 2.…”

Dehydration kinetics of piroxicam monohydrate and relationship to lattice energy and structure

“…Preferential escape of water molecules of a crystalline hydrate along tunnels25,26,28 or channels17,61 usually explains the kinetic model, which fits the quantitative dehydration data of crystalline powder, and the anisotropic frontal migration, which is qualitatively observed upon monitoring the dehydration of single crystals under polarized light. Under controlled experimental conditions, dehydration of an organic molecular crystal is a function of tunnel area and hydrogen bonding 25,26,28. A study of the crystal structure of PM reveals the absence of channels, layers, or tunnels, which can accommodate water molecules.…”

“…Direct observation of the dehydration behavior in single crystals by polarized light microscopy can often provide valuable information,25–28 complementary to that obtained from the crystal and molecular structure of the hydrate and anhydrate and from conventional kinetic analysis. However, kinetic data obtained from a single crystal may vary from crystal to crystal.…”

Identification of Phase Boundaries in Anhydrate/Hydrate Systems

“…The main region to distinguish between these solid-state forms occurs at $1950 nm, which is consistent with the hydroxyl combination band region. The hydroxyl group is pronounced in the spectrum for caffeine hydrate since water exists in channels within the crystal lattice 44 and is not detected in the NIR spectrum for anhydrous caffeine. This wavelength was not selected by Krzyzaniak et al 43 to develop their linear regression method due to the inability of NIR spectroscopy to differentiate between water in the crystalline lattice of caffeine hydrate and water sorbed to the surfaces of the crystal form present.…”