Study of a series of cobalt(II) sulfonamide complexes: Synthesis, spectroscopic characterization, and microbiological evaluation against M. tuberculosis. Crystal structure of [Co(sulfamethoxazole) 2 (H 2 O) 2 ]H 2 O Melina Mondelli a , Fernando Pavan b , Paula C. de Souza b , Clarice Q. Leite b , Javier Ellena c , Otaciro R. Nascimento d , Gianella Facchin a , María H. Torre a,⇑ a Química Inorgánica (DEC), Facultad de Química, UDELAR, Gral. Flores 2124, Montevideo, Uruguay b Faculdade de Ciencias Farmacêuticas, Unesp, C.P. 582, 14801-902 Araquara (SP), Brazil c Laboratorio de Cristalografía, Instituto de Física de São Carlos, USP, C.P. 369, 13560 São Carlos (SP), Brazil d Grupo de Biofísica Sérgio Mascarenhas, Instituto de Física de São Carlos, USP, C.P. 369, 13560 São Carlos (SP), Brazil highlights " We synthesized Co(II) complexes with general formulae [Co(sulfonamide) 2 ]nH 2 O. " IR, UV–Vis and EPR spectra showed different coordination depending on the ligand. " X-ray crystal structure of [Co(sulfamethoxazole) 2 (H 2 O) 2 ]H 2 O was obtained. " The activity against M. tuberculosis was evaluated. " The cytotoxicity on macrophage cells was studied. article info Article history: Received 22 July 2012 Received in revised form 22 September 2012 Accepted 24 September 2012 Available online 2 October 2012 Keywords: Cobalt complexes Sulfonamides Antimycobacteria activity X-ray structure IR spectra EPR abstract Nowadays, the research for new and better antimicrobial compounds is an important field due to the increase of immunocompromised patients, the use of invasive medical procedures and extensive surger- ies, among others, that can affect the incidence of infections. Another big problem associated is the occur- rence of drug-resistant microbial strains that impels a ceaseless search for new antimicrobial agents. In this context, a series of heterocyclic-sulfonamide complexes with Co(II) was synthesized and charac- terized with the aim of obtaining new antimicrobial compounds. The structural characterization was per- formed using different spectroscopic methods (UV–Vis, IR, and EPR). In spite of the fact that the general stoichiometry for all the complexes was Co(sulfonamide) 2 nH 2 O, the coordination atoms were different depending on the coordinated sulfonamide. The crystal structure of [Co(sulfamethoxazole) 2 (H 2 O) 2 ]H 2 O was obtained by X-ray diffraction showing that Co(II) is in a slightly tetragonal distorted octahedron where sulfamethoxazole molecules act as a head-to-tail bridges between two cobalt atoms, forming poly- meric chains. Besides, the activity against Mycobacterium tuberculosis, one of the responsible for tuberculosis, and the cytotoxicity on J774A.1 macrophage cells were evaluated. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Nowadays, the demand for new and better antimicrobial com- pounds makes relevant the research on this field. There is an in- crease of immunocompromised patients with HIV or receiving organ transplant-associated immunosuppressive therapy that have high probability to suffer infections. Besides, invasive medical procedures, extensive surgery and the use of prosthetic devices, among others, can also affect the incidence of infections. Another big problem associated is the occurrence of drug-resistant micro- bial strains that impels a ceaseless search for new antimicrobial agents [1]. In this context, sulfonamides still retain an important place in the chemotherapy of infections. They are the drugs of choice for the treatment of chancroid, nocardiosis and acute urinary tract infections caused by several microorganisms like Escherichia coli, Proteus mirabilis, among others. They can be used combined with other drugs in the treatment of otitis, meningitis, toxoplasmosis, 0022-2860/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.molstruc.2012.09.064 ⇑ Corresponding author. Tel.: +55 598 2 9249739; fax: +55 598 2 9241906. E-mail address: mtorre@fq.edu.uy (M.H. Torre). Journal of Molecular Structure 1036 (2013) 180–187 Contents lists available at SciVerse ScienceDirect Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc