Molecular salts of the isoniazid derivatives. Expanding the scope of sulfonate-pyridinium synthon to design materials

Physicochemical and Anti-fungal Studies of the Pharmaceutical Co-crystal/Salt of Fluconazole

Crystal engineering is one green alternative to organic synthesis that can be used to manipulate molecular behavior promptly and economically. We report the preparation and characterization of the pharmaceutical organic salt (FLC-C) of fluconazole (FLC) and organosulfonate (NDSA-2H), based on the sulfonate-pyridinium supramolecular synthon. Structural studies validate the crystallization of the two-component stoichiometric crystal with two molecules of water in the triclinic P1̅ space group. The anticipated proton transfer between the crystal forms leads to ionic interactions, augmenting the organic salt's thermal stability. Hirshfeld studies of FLC-C help to understand the role and significance of different types of intermolecular interactions responsible for crystal packing. The structural and theoretical studies indicate the absence of π-π interactions in FLC-C, which account for the incipience of solid-state emission in the product. The solubility studies establish augmented aqueous solubility of FLC-C over pristine FLC at physiological pH values of 2 and 7. Interestingly, in in vitro studies, FLC-C appears to serve as a potential alternative to FLC, displaying a wide spectrum of antifungal activity. FLC-C is active against several human pathogenic yeast strains, including the leading and emerging Candida strains (Candida albicans and Candida auris, respectively), at comparable and/or lower drug concentrations without showing any enhanced host cell toxicity. Interestingly, the pharmaceutical co-crystal also displays fluorescence properties inside the Candida cells.

Ammonia Recovery from Wastewater as a Fuel: Effects of Supporting Electrolyte on Ammonium Permeation through a Cation-Exchange Membrane

Electrodeionization (EDI) is used to recover ammonia from wastewater as a fuel, but how its performance for ammonia recovery is affected by the supporting electrolyte is not very clear. This study involved experimental tests and theoretical calculations on NH3 recovery, NH4 + permeation, and NH4 + and Na+ interacting with the functional groups in a cation exchange membrane (CEM) using Na2SO4 as the supporting electrolyte. The results demonstrated that a low concentration (≤0.250 mol L-1 of Na2SO4) was conducive to NH4 + permeation, while the a concentration (0.750 mol L-1 of Na2SO4) hindered NH4 + permeation. A maximum recovery efficiency of ammonia of 80.00%, a current efficiency of 70.10%, and an energy balance ratio of 0.66 were obtained at 0.250 mol L-1 of Na2SO4. Numerical results indicated that an increase in Na2SO4 concentration caused severe concentration polarization that resisted NH4 + migration in the CEM. The DFT results demonstrated that competitive adsorption of Na+ to the CEM hindered NH4 + migration. The weaker interacting force between NH4 + and the sulfonate functional group (-SOH3) in comparison to that between Na+ and -SOH3 might be related to the geometric and orientation effects, which generated an additional energy barrier for NH4 + transport. Therefore, this study suggests that the supporting electrolyte concentration should be matched with that of the desalted ions.