Complexos de Ag(I) e Cu(II) com sulfonamidas

Abstract

Ag(I) AND Cu(II) COMPLEXES WITH SULFONAMIDES: STRUCTURAL CHARACTERIZATION AND ANTIBACTERIAL ASSAYS. The present work describes the synthesis and spectroscopic characterization of two silver(I) complexes with the ligands sulfathiazole (AgC 9 H 8 N 3 O 2 S 2 , Ag-SFT) and sulfamethoxazole (AgC 10 H 10 N 3 O 3 S, Ag-SFM) and a novel copper(II) complex with sulfathiazole and 2,2'-bipyridine (CuC 28 H 26 N 8 O 5 S 4 , Cu[(SFT) 2 (bipy)]•H 2 O). The silver(I) complexeswere prepared from aqueous solutions of the ligands and silver nitrate in an alkaline medium, whereas the copper(II) complex was prepared from a methanolic solution of copper nitrate and bipyridine, and an alkaline solution of the SFT ligand in methanol.Elemental analysis results indicate a 1:1 (metal/ligand) ratio for the two silver(I)complexes. Elemental analysis and inductively coupled plasma optical emission spectroscopy suggest a 2:1:1 (SFT/copper/bipy) ratio for the copper(II) complex. Spectroscopic techniques such as1 H, 13 C and 15 N NMR and infrared spectroscopy indicate the coordination of the sulfonamides to Ag(I) and Cu(II) ions by the nitrogen atom of the SO 2 -N group. Crystal structures of the complexes Ag-SFT and [Cu(SFT) 2 (bipy)] were solved by powder X-ray diffraction. In the Ag-SFT complex the ligand is bridging two silver(I) ions in a dimeric structure, with the participation of the nitrogen atom of the thiazole heterocycle. In the [Cu(SFT) 2 (bipy)] complex, sulfathiazole has a bidentate coordination to copper through the nitrogens of SO 2 -N and thiazole groups. Both SFT ligands and bypiridine form a distorted octahedral geometry around the Cu(II) center. Antibacterial studies have shown antibacterial activity of Ag-SFT and Ag-SFM complexes over Gram positive and Gram negative bacteria, with MIC (minimum inhibitory concentration) values less or equal to 0.050 mmol L -1 . This activity is similar to that of silver-sulfadiazine. The [Cu(SFT) 2 (bipy)] complex did not show activity against Gram positive bacteria Staphylococcus aureus.For Gram negative bacteria MIC values are in the range 0.10-0.84 mmol L -1 . Both silver(I) and copper(II) complexes were more active than their precursors. Antioxidant studies of the copper(II) complex showed that it is capable of reducing the radical cation ABTS •+ in 13% and 20%, considering a complex molar percentage of 10% and 20%, respectively. The copper complex was not able to reduce DPPH • radical in the considered conditions. Abreviaturas, acrônimos e símbolosAbsabsorbância ABTS -2,2'-azino-bis-(ácido 3-etilbenzotiazolina-6-sulfônico) Ag-SFDsulfadiazina de prata Ag-SFMcomplexo de prata com sulfametoxazol Ag-SFTcomplexo de prata com sulfatiazol ATCC − American Type Culture Collection ATPtrifosfato de adenosina Bactrim ®sulfametoxazol + trimetoprima BHI − Brain Heart Infusion BHT -2,6-di-terc-butil-4-metilfenol; hidroxitolueno butilado bipy -2,2'-bipiridina [Cu(SFT) 2 (bipy)]complexo de cobre com sulfatiazol e bipiridina DHOágua em que um hidrogênio foi trocado por deutério DMSOdimetilsulfóxido DMS...