Triclinic polymorph of sulfasalazine

Abstract

In this modification of the title compound, 5-(4-[(2-pyridylamino)sulfonyl]phenyldiazenyl)salicylic acid, C(18)H(14)N(4)O(5)S, the molecule is present in the amide tautomeric form. Two azo-bridged phenyl rings render the bulk of the molecule planar, with the carboxylic acid group at one terminal and the pyridylamino residue at the other. The repeating unit in the crystal is a centrosymmetric dimer containing two identical R-2/2-(8) hydrogen-bonded ring systems, each involving the carboxylic acid and pyridylamino moieties. Additional stabilization is due to an intramolecular hydrogen bond between the 2-hydroxyl group and the carbonyl O atom of the carboxylic acid group, as well as intermolecular pi-pi stacking.

A Novel Mechanism for Azoreduction

“…This torsion about the azo bond is unusual, as the phenyl rings linked by the azo bond in the small-molecule crystal structure of the related drug sulfasalazine are coplanar. 36 The most likely explanation for the bent configuration is that balsalazide exists as the hydrazone tautomer when bound to paAzoR1 (Fig. 4).…”

Tormat: a program for the automated structural alignment of molecular conformations

“…In Fig. 3, the best superimposition between the tautomers of 5-{4-[(pyrid-2-ylamino)sulfonyl]phenylazo}salicylic acid, in the amine (QIJZOY; Filip et al, 2001) and imine forms (QIJZOY01; Blake et al, 2004), was obtained via the removal of tautomeric H atoms. A partial conformational match of the compound 7-chloro-5-(2-chlorophenyl)-1,3-dihydro-3-hydroxy-1,4benzodiazepin-2-one (CPHAZO; Bandoli & Clemente, 1976) to -alprazolam (MENMIB01; Reck et al, 1996) is illustrated in Fig.…”

Multi-laminated metal hydroxide nanocontainers for oral-specific delivery for bioavailability improvement and treatment of inflammatory paw edema in mice

“…However, the sample containing a second coat The three-dimensional molecule and the spatial orientation of the drug (Fig. 4A) was plotted using ChemOffice software and the dimensions from the crystal data of sulfasalazine were taken into account [86]. Based on this information and the XRD pattern, the molecule was fit into the layered matrix, as shown in Fig.…”