Molecular structures of two copper complexes with the pharmaceuticals norfloxacin and tinidazole, when powder X-ray diffraction assists multi-domain single-crystal X-ray diffraction

Abstract

The crystal structures of bis[1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-ium-4-yl)-1,4-dihydroquinoline-3-carboxylato]copper(II) sulfate heptahydrate, [Cu(C16H18FN3O3)2]SO4·7H2O or [Cu(nor)2]SO4·7H2O (nor is norfloxacin), and bis{1-[2-(ethylsulfonyl)ethyl]-2-methyl-5-nitroimide}dinitratocopper(II), [Cu(NO3)2(C8H13N3O4S)2] or [Cu(NO3)2(tnz)2] (tnz is tinidazole), were solved by X-ray diffraction. Both complexes crystallize in the space group P21/c, with Z = 4 (for nor) and Z = 2 (for ntz) molecules per unit cell. In [Cu(nor)2]SO4·7H2O, the CuII ion is at the centre of a square-planar environment, trans coordinated to two independent norfloxacin molecules in the zwitterionic form acting as bidentate ligands through one of the carboxyl (cbx) and the carbonyl (cb) O atoms. The solid is further stabilized by an extensive network of N—H...O(sulfate), N—H...O(cbx), N—H...OW, OW—H...O(sulfate) and OW—H...OW hydrogen bonds. The [Cu(NO3)2(tnz)2] complex is centrosymmetric, with the CuII ion in a square planar environment, coordinated to a tinidazole molecule acting as a monodentate ligand through its imidazole N atom and to one nitrate O atom. The vibrational FT–IR absorption spectra and thermal behaviour of the complexes were also studied and are briefly discussed based on the crystal structures.

Synthesis and Structure Characterization of Three Pharmaceutical Compounds Based on Tinidazole

“…Compared with the raw materials TNZ, 2,6-DHBA, 4-MAC, and 5-C-2-HBA, the characteristic peaks in compounds 1-3 are red-shifted or blue-shifted due to the formation of hydrogen bonds. For instance, the C = N [37] stretching band at 1642 cm −1 and the characteristic peaks of the benzene ring [38] at 1585 cm −1 , 1504 cm −1 , and 1450 cm −1 are respectively blue-shifted or red-shifted in compound 1 compared with the C = N stretching band of 1630 cm −1 in pure TNZ or the characteristic framework vibrations peaks 1631 cm −1 , 1579 cm −1 and 1468 cm −1 of the benzene ring in pure 2,6-DHBA. The IR analysis showed that compounds 1-3 are composed of TNZ and 2,6-DHBA, 4-MAC, and 5-C-2-HBA, respectively, and the interactions between them are hydrogen bonds, which was confirmed by the crystal structure analysis (Figure S1).…”