2-[3-(1H-Benzimidazol-2-yl)prop-yl]-1H-benzimidazol-3-ium 3,4,5-tri-hydroxy-benzoate-1,3-bis-(1H-benzimidazol-2-yl)propane-ethyl acetate (2/1/2.94): co-crystallization between a salt, a neutral mol-ecule and a solvent.

The chemical formula of the title compound, 2C17H17N4 +·2C7H5O5 -·C17H16N4·2.94C4H8O2, was established by X-ray diffraction of a single-crystal obtained by reacting 1,3-bis-(benzimidazol-2-yl)propane (L) and gallic acid (HGal) in ethyl acetate. The mol-ecular structure can be described as a salt (HL)+(Gal)- co-crystallized with a mol-ecule L, with a stoichiometric relation of 2:1. Moreover, large voids in the crystal are filled with ethyl acetate, the amount of which was estimated by using a solvent mask during structure refinement, affording the chemical formula (HL +·Gal-)2·L·(C4H8O2)2.94. The arrangement of components in the crystal is driven by O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds rather than by π-π or C-H⋯π inter-actions. In the crystal, mol-ecules and ions shape the boundary of cylindrical tunnels parallel to [100] via R (rings) and D (discrete) supra-molecular motifs. These voids, which account for about 28% of the unit-cell volume, contain disordered solvent mol-ecules.

Pharmaceutical co-crystals of posaconazole for improvement of physicochemical properties

Abstract Posaconazole exerts an extended spectrum of antifungal activity against various strains of clinically relevant moulds and yeasts. In recent years, antifungal triazole posaconazole has become increasingly important for the prophylaxis and treatment of systemic mycoses. After oral administration of posaconazole, absolute bioavailability has been estimated to range from 8% to 47%. Pharmaceutical co-crystallization is a promising approach for improving dissolution rate or manipulating other physical properties of API. The objective of this study is to improve the dissolution rate of posaconazole by co-crystallization. A 1:1 stoichiometric co-crystals of adipic acid were prepared by solvent assisted grinding method. The prepared co-crystals were subjected to solid-state characterization by FTIR, PXRD and DSC studies. The physicochemical properties of posaconazole and co-crystals were assessed in terms of melting point, flowability and dissolution rate. The results indicated improvement in flow property and dissolution rate. In vitro dissolution profile of co-crystals showed a significant increased dissolution of posaconazole from initial period in 0.1 N hydrochloric acid solution. The dissolution efficiency for posaconazole-adipic acid co-crystal was 61.65 % against posaconazole, 46.58 %. Thus, co-crystallization can be a promising approach to prepare posaconazole-adipic acid co-crystals with improved physicochemical properties.

The 1:1 co-crystal of 2-bromo-naphthalene-1,4-dione and 1,8-di-hydroxy-anthracene-9,10-dione: crystal structure and Hirshfeld surface analysis.

The asymmetric unit of the title co-crystal, C10H5BrO2·C14H8O4 [systematic name: 2-bromo-1,4-di-hydro-naphthalene-1,4-dione-1,8-dihy-droxy-9,10-di-hydro-anthracene-9,10-dione (1/1)], features one mol-ecule of each coformer. The 2-bromo-naphtho-quinone mol-ecule is almost planar [r.m.s deviation of the 13 non-H atoms = 0.060 Å, with the maximum deviations of 0.093 (1) and 0.099 (1) Šbeing for the Br atom and a carbonyl-O atom, respectively]. The 1,8-di-hydroxy-anthra-quinone mol-ecule is planar (r.m.s. deviation for the 18 non-H atoms is 0.022 Å) and features two intra-molecular hy-droxy-O-H⋯O(carbon-yl) hydrogen bonds. Dimeric aggregates of 1,8-di-hydroxy-anthra-quinone mol-ecules assemble through weak inter-molecular hy-droxy-O-H⋯O(carbon-yl) hydrogen bonds. The mol-ecular packing comprises stacks of mol-ecules of 2-bromo-naphtho-quinone and dimeric assembles of 1,8-di-hydroxy-anthra-quinone with the shortest π-π contact within a stack of 3.5760 (9) Šoccurring between the different rings of 2-bromo-naphtho-quinone mol-ecules. The analysis of the Hirshfeld surface reveals the importance of the inter-actions just indicated but, also the contribution of additional C-H⋯O contacts as well as C=O⋯π inter-actions to the mol-ecular packing.

Mechanochemical synthesis and crystal structure of a 1:2 co-crystal of 1,3,6,8-tetra-aza-tri-cyclo[4.3.1.13,8]undecane (TATU) and 4-chloro-3,5-dimethyl-phenol.

Solvent-free treatment of 1,3,6,8-tetra-aza-tri-cyclo-[4.3.1.13,8]undecano (TATU) with 4-chloro-3,5-di-methyl-phenol led to the formation of the title co-crystal, C7H14N4·2C8H9ClO. The asymmetric unit contains one aminal cage mol-ecule and two phenol mol-ecules linked via two O-H⋯N hydrogen bonds. In the aminal cage, the N-CH2-CH2-N unit is slightly distorted from a syn periplanar geometry. Aromatic π-π stacking between the benzene rings from two different neighbouring phenol mol-ecules [centroid-centroid distance = 4.0570 (11) Å] consolidates the crystal packing.

Preparation and Physical Characterization of a Diclofenac-Ranitidine Co-precipitate for Improving the Dissolution of Diclofenac.

Mixing aqueous solutions of sodium diclofenac (DIC-Na) and ranitidine hydrochloride (RAN·HCl) afforded an off-white solid (DIC-RAN) that was investigated from the microscopic, thermal, diffractometric, spectroscopic, and functional (chemometrics-assisted dissolution) points of view. The solid has a 2:1 (DIC:RAN) molar ratio according to (1)H nuclear magnetic resonance spectroscopy. It is thermally stable, displaying a broad endothermic signal centered at 105°C in the thermogram, and its characteristic reflections in the powder X-ray diffractogram remained unchanged after a 3-month aging period. Scanning electron microscopy micrographs uncovered its morphology, whereas the spectral data suggested an interaction between the carboxylic acid of DIC and the alkyldimethylamino moiety of RAN. The dissolution of DIC-RAN was monitored at different pH values by an ultraviolet/chemometrics procedure, being complete within 5 min at pH 6.8. This compares favorably with the dissolution of a DIC-Na sample of the same particle size.

Crystal structure of 4,4'-(disulfanediyl)dibutanoic acid-4,4'-bipyridine (1/1).

4,4'-(Disulfanediyl)dibutanoic acid (dtba) and 4,4'-bipyridine (4,4'-bpy) crystallize in an 1:1 ratio, leading to the title co-crystal with composition C8H14O4S2·C10H8N2. A distinctive feature of the crystal structure is the geometry of the dtba moiety, which appears to be stretched [with a 9.98 (1) Šspan between outermost carbons] and acts as an hydrogen-bonding connector, forming linear chains along [-211] with the 4,4'-bpy moiety by way of O-H⋯N hydrogen bonds and C-H⋯O interactions. The influence of the mol-ecular shape on the hydrogen-bonding pattern is analysed by comparing the title compound and two other 4,4'-bpy co-crystals with closely related mol-ecules of similar formulation but different geometry, showing the way in which this correlates with the packing arrangement.

Evaluation of analytical tools and multivariate methods for quantification of co-former crystals in ibuprofen-nicotinamide co-crystals.

Co-crystals are multicomponent substances designed by the addition of two or more different molecules in a same crystallographic pattern, in which it differs from the crystallographic motif of its co-formers. The addition of highly soluble molecules, like nicotinamide, in the crystallographic pattern of ibuprofen enhances its solubility more than 7.5 times, improving the properties of this widely used drug. Several analytical solid state techniques are used to characterize the ibuprofen-nicotinamide co-crystal, being the most used: mid-infrared (ATR-FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRPD) and Raman spectroscopy. These analytical solid state techniques were evaluated to quantify a mixture of ibuprofen-nicotinamide co-crystal and its co-formers in order to develop a calibration model to evaluate the co-crystal purity after its synthesis. Raman spectroscopy showed better result than all other techniques with a combination of multivariate calibration tools, presenting lower values of calibration and prediction errors. The partial least squares regression model gave a mean error lower than 5% for all components presented in the mixture. DSC and mid-infrared spectroscopy proved to be insufficient for quantification of the ternary mixture. XRPD presented good results for quantification of the co-formers, ibuprofen and nicotinamide, but fair results for the co-crystal. This is the first report of quantification of ibuprofen-nicotinamide co-crystal, among its co-formers. The quantification is of great importance to determine the yield of the co-crystallization reactions and the purity of the product obtained.