Structural, quantum chemical, vibrational and thermal studies of a hydrogen bonded zwitterionic co-crystal (nicotinic acid: pyrogallol)

A cocrystal of L-ascorbic acid with picolinic acid: the role of O—H...O, N—H...O and C—H...O hydrogen bonds and L-ascorbic acid conformation in structure stabilization

“…The calculations were performed using the GAUSSIAN09 program package (Frisch et al, 2009) installed at the SKIF 'Cyberia' supercomputer of the National Research Tomsk State University. Density functional theory (DFT) with hybrid functional B3LYP (Lee et al, 1988;Becke, 1993) and the 6-311++G(d,p) split-valence basis set, with the addition of polarization and diffuse functions for heavy and H atoms, was used since this method provides a good correlation of the calculation results with the experiment (Latha et al, 2020;Jyothi et al, 2019;Thangarasu et al, 2018;Prabha et al, 2017).…”

“…The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) play a decisive role in the stability and chemical activity of the molecules (Fleming, 1976). The energies of the HOMO and LUMO characterize the ionization potential and electron affinity, respectively, while the HOMO-LUMO gap is associated with the chemical stability of the molecule (Prabha et al, 2017). The HOMO and LUMO energies of the l-Asc-Pic cocrystal and of the individual ascorbic and picolinic acid molecules, as well as the type of orbitals, were calculated by the B3LYP method and the results are presented in Fig.…”

Adducts of N-Heterocyclic Drugs, Niacin, Allopurinol, and Amiloride, with 2,4-Pyridinedicarboxylic Acid Coformer

“…Contrary to ALP and AMI, niacin and its derivatives, nicotinamide and isonicotinamide, are popular agents for co-crystallization in pharmaceutical co-crystal studies. For NIA, the extended information in the CSD is available, and NIA is reported in four different ionization states, as a pyridinium cation (the mostly frequently met form), as a nicotinate anion in the drug–drug solids with blonanserin, clofazimine, pyrimethamine, tegaserod, and lamotrigine. − In the zwitterion form, due to the intramolecular proton transfer, NIA is reported in adducts with rac- and (+)-hesperetin, hydrochlorothiazide, pyrogallol, ,, and with several carboxylic acids. ,, Finally, only two examples report NIA in the neutral form in adducts with β-cyclodextrin (β-CD) and 4-aminobenzoic acid. , …”

Acid–ammonium heterodimer and N(ammonium)–H...N(pyridine) synthon preference in three salts of nicotinic acid with (1R,2R)-1,2-diphenylethylenediamine

“…The solubility of (DPEN)(NA) 2 at pH = 4.5 is increased the most, nearly seven times from 22.7 (2) mg ml À1 to 152.2 (3) mg ml À1 , whereas it is four times than that of NA at pH = 1.2 and 6.8. The solubility of the NA salts with DPEN is also higher than that of (nicotinic acid) 2 (pyrogallol) 2 (50 mg ml À1 ) (Prabha et al, 2017). (DPEN)(NA) 2 remains stable and (DPEN)(NA) 2 (EA) has changed to (DPEN)(NA) 2 after solubility experiments as shown in PXRD patterns (Figs.…”

“…The vitamin function of nicotinic acid, known as vitamin B 3 (Blum, 1996;Block, 1996), has led to its widespread use as an additive in food, forage and cosmetics (Block, 1996;Carlson, 2005). In addition, NA as a classical API coformer has also been widely used in crystal engineering in pharmaceutical science (Xie et al, 2017;Freitas et al, 2015;Ganduri et al, 2017;Solomon et al, 2017;Prabha et al, 2017).…”