Bis[5-oxo-4,5-dihydro-8H-2-azonia-4,8,9-trizabicyclo[4.3.0]nona-2,6,9(1)-triene] sulfate

Abstract

In the crystal structure of the title compound, 2C5H5N4O+·SO4 2−, N—H⋯O hydrogen bonds assemble the mol­ecules into a two-dimensional network structure parallel to the cb plane. The S atom of the sulfate ion lies on a special position on a twofold axis.

Mechanosynthesis of Stable Salt Hydrates of Allopurinol with Enhanced Dissolution, Diffusion, and Pharmacokinetics

“…ALO is a weak base (p K a 10.1) in which pyrimidine sp 2 nitrogen as the most potent electron pair donor is expected to form neutral/ionic hydrogen bonds with the acidic coformers. This was confirmed by the reported crystal structure of chloride (CCDC refcode FAXFUF10) and sulfate (refcode OGEREY) salts , and cocrystals with pyridine 2,4-dicarboxylic acid (p K a 2.15), 2,4-dihydroxybenzoic acid (p K a 3.1, 8.5), and isonicotinamide . These multicomponent solids suggest that coformers should be stronger carboxylic acid (p K a <2) compared to the reported acidic coformers to produce organic molecular salts of ALO.…”

“…ALO consists of planar pyrimidine and pyrazole-fused rings, and out of them, pyrimidine "N" is more basic that is confirmed with the reported HCl and H 2 SO 4 salts. 21,22 In the ALO crystal structure (refcode ALOPUR, P2 1 /c, Z = 4), two ALO molecules form a N−H•••N centrosymmetric dimer between pyrimidine and pyrazole nitrogen atoms 20 (refer Figure S5a The idea of synthesizing organic salts of ALO with OXA and MLE was similar to the reported inorganic chloride and sulfate salts that may offer improved solubility and permeability. We faced difficulty to produce single crystals of ALO−OXA and ALO−MLE hydrates irrespective of crystallization methods.…”

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

“…The distribution of N- and O-bound hydrogen atoms in the ALP drug and PDA coformer molecules and the bond distances values (Table S2) unambiguously indicate that no proton transfer occurs, and all components exist in the neutral forms. Thus, compound 2 can be interpreted as a co-crystal hydrate. , Two crystallographically unique ALP molecules exist in the oxo-tautomeric form that is agreed with the ALP crystalline pure form and its chloride and sulfate salts. − Both ALP and PDA heterocyclic molecules have almost planar molecular skeletons. Similar to 1 , one of the carboxylic groups in PDA displays in the plane of the pyridine ring, while another one is twisted relative to the same plane as the corresponding dihedral angles of 1.4(8)° and 8.1(8)° indicate.…”

“…ALP is often used as an efficient model for quantum-chemical simulations for clarifying the details of crystalline packing and predicting an unknown crystal structure of xanthine. − According to the X-ray data, the layered structure of ALP is built of hydrogen-bonded molecules with a stacking distance between molecules equal to 3.301 Å. The oxo-form fixed in the crystal of ALP agrees well with the predicted higher stability among the possible tautomers. − In addition to ALP’s pure crystalline form, only two crystal structures of its hydrochloride and sulfate salts where the pyrimidine moiety is protonated are known. , …”

“…All drug molecules and coformer have several binding sites of different acidity/basicity capable of participating in hydrogen-bonding systems and proton transfer, while their planar skeletons are predisposed for potential stacking interactions in these systems. The results of this study contribute to the quite limited crystallographic data available in the CSD (CSD version 5.38 updates Feb 2017) for ALP − and AMI − drugs.…”