Design, Preparation, Characterization and Evaluation of Five Cocrystal Hydrates of Fluconazole with Hydroxybenzoic Acids

Multi-component forms of the 2nd generation H1 receptor antagonist drug, Bilastine and its enhanced physicochemical characteristics

Bilastine (BIL) is a novel 2nd generation antihistamine medication is used to treat symptoms of chronic urticaria and allergic rhinitis. However, its poor solubility limits its therapeutic efficacy. In order to enhance the physicochemical characteristics of BIL, various molecular adducts of BIL (Salt, hydrate and co-crystal) were discovered in this study using two distinct salt-formers: Terephthalic acid (TA), 2,4-Dihydroxybenzoic acid (2,4-DHBA), and three nutraceuticals (Vanillic Acid (VA), Hydroquinone (HQN) and Hippuric acid (HA)). Various analytical methods were used to examine the synthesised adducts, including Powder X-Ray Diffraction (PXRD), Single Crystal X-ray Diffraction (SCXRD), and thermal analysis (Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC)). Single-crystal X-ray diffraction (SCXRD) studies avowed that the architectures of the molecular adducts are maintained in the solid state by an array of strong (N+H⋯O-, NH⋯O, OH⋯O) and weak (CH⋯O) hydrogen bonds. Additionally, a solubility test was performed to establish the in vitro release characteristics of newly synthesised BIL adducts and it observed that most of the molecular adducts exhibit higher rates of dissolution in comparison to pure BIL; in particular, BIL.TA.HYD showed the highest solubility and the fastest rate of dissolution. Moreover, experiments on flux permeability and diffusion demonstrated that the BIL.TA.HYD and BIL.VA salts had strong permeability and a high diffusion rate. In addition, the synthesized adduct's stability was assessed at 25 °C and 90 % ± 5 % relative humidity, and it was found that all the molecular salts were stable and did not undergo any phase changes or dissociation. The foregoing result leads us to believe that the newly synthesized molecular adducts' increased permeability and solubility will be advantageous for the creation of novel BIL formulations.

Hydrophilic Cocrystals with Water Switched Luminescence

Utilizing water molecules to regulate the luminescence properties of solid materials is highly challenging. Herein, we develop a strategy to produce water-triggered luminescence-switching cocrystals by coassembling hydrophilic donors with electron-deficient acceptors, where 1,2,4,5-Tetracyanobenzene (TCNB) was used as the electron acceptor and pyridyl benzimidazole derivatives were used as the electron donors enabling multiple hydrogen-bonds. Two cocrystals, namely 2PYTC and 4PYTC were obtained and showed heat-activated emission, and such emission could be quenched or weakened by adding water molecules. The cocrystal structure exhibited the donor molecule that can form multiple hydro bonds with water and acceptor molecules due to the many nitrogen atoms of them. The analyses of the photophysical data, powder X-ray diffraction, and other data confirmed the reversible fluorescence "on-off" effects were caused by eliminating and adding water molecules in the crystal lattice. The density functional theory calculations indicate that the vibration of the O-H bond of water molecules in the cocrystal can absorb the excitation energy and suppress fluorescence. Furthermore, the obtained cocrystals also showed temperature, humidity, and H+ /NH4 + responsive emission behavior, which allows their applications as thermal and humidity sensors, and multiple information encryptions. This research paves the way for preparing intelligent hydrophilic organic cocrystal luminescent materials.