Virtual Screening, Structural Analysis, and Formation Thermodynamics of Carbamazepine Cocrystals

In this study, the existing set of carbamazepine (CBZ) cocrystals was extended through the successful combination of the drug with the positional isomers of acetamidobenzoic acid. The structural and energetic features of the CBZ cocrystals with 3- and 4-acetamidobenzoic acids were elucidated via single-crystal X-ray diffraction followed by QTAIMC analysis. The ability of three fundamentally different virtual screening methods to predict the correct cocrystallization outcome for CBZ was assessed based on the new experimental results obtained in this study and data available in the literature. It was found that the hydrogen bond propensity model performed the worst in distinguishing positive and negative results of CBZ cocrystallization experiments with 87 coformers, attaining an accuracy value lower than random guessing. The method that utilizes molecular electrostatic potential maps and the machine learning approach named CCGNet exhibited comparable results in terms of prediction metrics, albeit the latter resulted in superior specificity and overall accuracy while requiring no time-consuming DFT computations. In addition, formation thermodynamic parameters for the newly obtained CBZ cocrystals with 3- and 4-acetamidobenzoic acids were evaluated using temperature dependences of the cocrystallization Gibbs energy. The cocrystallization reactions between CBZ and the selected coformers were found to be enthalpy-driven, with entropy terms being statistically different from zero. The observed difference in dissolution behavior of the cocrystals in aqueous media was thought to be caused by variations in their thermodynamic stability.

Two Faces of Water in the Formation and Stabilization of Multicomponent Crystals of Zwitterionic Drug-Like Compounds

Two new hydrated multicomponent crystals of zwitterionic 2-aminonicotinic acid with maleic and fumaric acids have been obtained and thoroughly characterized by a variety of experimental (X-ray analysis and terahertz Raman spectroscopy) and theoretical periodic density functional theory calculations, followed by Bader analysis of the crystalline electron density) techniques. It has been found that the Raman-active band in the region of 300 cm−1 is due to the vibrations of the intramolecular O-H...O bond in the maleate anion. The energy/enthalpy of the intermolecular hydrogen bonds was estimated by several empirical approaches. An analysis of the interaction networks reflects the structure-directing role of the water molecule in the examined multicomponent crystals. A general scheme has been proposed to explain the proton transfer between the components during the formation of multicomponent crystals in water. Water molecules were found to play the key role in this process, forming a “water wire” between the COOH group of the dicarboxylic acid and the COO– group of the zwitterion and the rendering crystal lattice of the considered multicomponent crystals.

Azilsartan piperazine salt solvate and monohydrate: preparation, crystal structure, enhanced solubility and oral bioavailability

Two azilsartan–piperazine salt solvates and a monohydrate feature crystal structural diversity and improve the azilsartan solubility over that of the free Az form. Az–Pz·EtOH and Az–Pz·H₂O improve the plasma azilsartan concentration C_max and AUC over the free Az form.

Ethinyl estradiol cocrystals assembled by chain structures: improvement in stability and solubility

EE could form cocrystals with N-containing CCFs to attune the hygroscopicity and dissolution performance.

An integrated approach (synthetic, structural and biological) to the study of aroylhydrazone salts

A change of anion or aroylhydrazone substituent position results in salts of different connectivities, thermal stabilities and properties.

Molecular structures of 3-[(2,2,3,3-tetrafluoropropoxy)methyl]- and 3-[(2,2,3,3,3-pentafluoropropoxy)methyl]pyridinium saccharinates

The salts 3-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium saccharinate, C₉H₁₀F₄NO⁺·C₇H₄NO₃S^-, (1), and 3-[(2,2,3,3,3-pentafluoropropoxy)methyl]pyridinium saccharinate, C₉H₉F₅NO⁺·C₇H₄NO₃S^-, (2), i.e. saccharinate (or 1,1-dioxo-1λ⁶,2-benzothiazol-3-olate) salts of pyridinium with -CH₂OCH₂CF₂CF₂H and -CH₂OCH₂CF₂CF₃ meta substituents, respectively, were investigated crystallographically in order to compare their fluorine-related weak interactions in the solid state. Both salts demonstrate a stable synthon formed by the pyridinium cation and the saccharinate anion, in which a seven-membered ring reveals a double hydrogen-bonding pattern. The twist between the pyridinium plane and the saccharinate plane in (2) is 21.26 (8)° and that in (1) is 8.03 (6)°. Both salts also show stacks of alternating cation-anion π-interactions. The layer distances, calculated from the centroid of the saccharinate plane to the neighbouring pyridinium planes, above and below, are 3.406 (2) and 3.517 (2) Å in (1), and 3.409 (3) and 3.458 (3) Å in (2).

Improving solubility and avoiding hygroscopicity of tetrahydroberberine by forming hydrochloride salts by introducing solvents: [HTHB]Cl, [HTHB]Cl·CH3OH and [HTHB]Cl·CH3COOH

Improving the solubility of tetrahydroberberine by forming hydrochloride salts and avoiding the hygroscopicity.

Two-component molecular crystals: evaluation of the formation thermodynamics based on melting points and sublimation data

An approach to estimating co-crystal sublimation thermodynamic characteristics has been developed. The thermodynamic functions of the formation process of 281 co-crystals have been obtained and analyzed.

Coordination compounds of a hydrazone derivative with Co(iii), Ni(ii), Cu(ii) and Zn(ii): synthesis, characterization, reactivity assessment and biological evaluation

Increasing inhibitory effect of Zn-Hp2DAP < Hp2DAP < Co-Hp2DAP on ABC transporter MDR1 drug efflux pump.

Cocrystals of the antiandrogenic drug bicalutamide: screening, crystal structures, formation thermodynamics and lattice energies

Two new cocrystals of the antiandrogenic drug bicalutamide with benzamide and salicylamide are reported. Relationships between crystal structures, melting temperatures, aqueous dissolution, formation thermodynamics and crystal lattice energies of the cocrystals are investigated.