Antibacterial, Cytotoxic Studies and Characterization of Some Newly Synthesized Symmetrical , -Bis(disubstituted)isophthalyl-bis(thioureas) and Their Cu(II) and Ni(II) Complexes

A series of some novel , -bis(disubstituted)isophthalyl-bis(thioureas) compounds with general formula [C6H4 {CONHCSNHR}2], where R = 2-ClC6H4S (L1), 3,5-(Cl)2C6H3 (L2), 2,4-(Cl)2C6H3 (L3), 2,5-(Cl)2C6H3 (L4), and 2-NH2C6H4 (L5), and their Cu(II) and Ni(II) complexes (C1–C10) have been synthesized. These compounds (L1–L5) and their metal(II) complexes (C1–C10) have been characterized by elemental analysis, infrared spectroscopy, 1H NMR and 13C NMR spectroscopy, magnetic moments, and electronic spectral measurements. The ligands are coordinated to metal atom in a bidentate pattern producing a neutral complex of the type [ML]2. These compounds (L1–L5) and their metal(II) complexes (C1–C10) were also screened for their antibacterial and cytotoxic activities. 1. Introduction Thioureas, an emerging class of compounds, were first synthesized by Neucki [1]. Thiourea derivatives hold broad range of applications in the field of medicine, agriculture, and analytical chemistry. These compounds show a comprehensive range of biological activities such as antiviral [2, 3], antibacterial [4], fungicidal [5–7], analgesic, herbicidal [8, 9], plant growth regulating [10], antiaggregating [11], antiarrhythmic [12], local anesthetic [13], and antihyperlipidemic activities [14]. Some thioureas have been recently described as effective antitumor and nonnucleoside inhibitors of HIV reverse transcriptase [15]. Recently reported [16] some dithiourea derivatives exhibited cytotoxicity against various cancer cells, and one of these indicated best inhibition activities against KB and CNE2 with IC50 values of 10.72 and 9.91 micrometer, respectively. In view of these results, our interest increased in the synthesis of some new bis(thiourea) derivatives which were characterized by spectroscopic techniques such as FTIR, 1H NMR, and 13C NMR. These derivatives are stable and contain at least two potential donor atoms as O and S. These have been found to display surprisingly rich coordination chemistry at their active sites especially with transition metals. Metalloorganic chemistry is becoming an emerging area of research due to the demand for new metal-based antibacterial and antifungal compounds [17, 18]. Many investigations have proved that binding of a drug to a metalloelement enhances its activity, and in some cases, the complex possesses even more healing properties than the parent drug [19]. Recently, a number of attempts have been made to obtain Cu(II) and Ni(II) complexes with thioureas [20–22]. In view of these observations, we became interested in the synthesis of some new