Synthesis, characterization, single crystal XRD and biological screenings of organotin(IV) derivatives with 4-(2-hydroxyethyl)piperazine-1-carbodithioic acid

Abstract

<p>Organotin(IV) thiocarboxylates R₂SnL₂ (R = Me: <b>1:</b> Ph: <b>2</b>)/R₂(Cl)SnL (R = <i>n</i>-Bu: <b>3</b>; Ph: <b>4</b>)/R₃SnL (R = Me: <b>5</b>; <i>n</i>-Bu: <b>6</b>; Ph: <b>7</b>), where L = 4-(2-hydroxyethyl)piperazine-1-carbodithioate, have been synthesized by stirring together 1,2-hydroxyethylpiperazine and CS₂ in methanol, and then refluxing with a di-/triorganotin chloride. The synthesized products have been characterized by various spectroscopic (IR, ¹H NMR, ¹³C NMR, EI-MS) techniques and single crystal XRD. FT-IR data indicate bidentate binding of the ligand. The magnitude of ²<i>J</i>(¹¹⁹Sn–¹H) demonstrated a skew trapezoidal environment around tin(IV) in <b>1,</b> whereas the metal geometry in <b>5</b> was between distorted tetrahedral and trigonal bipyramidal in solution. ¹³C NMR revealed four- and five-coordinate environments in <b>6</b> and <b>7</b>, respectively, in non-coordinating solvent. EI-MS data agreed very well with the structural skeleton of the products. Single crystal XRD study has shown skew trapezoidal- and trigonal-bipyramidal Sn(IV) in <b>1</b> and <b>7</b>, respectively. Compound <b>6</b> interacted with salmon sperm DNA (SS-DNA) with significant hypochromic effect and an intercalating mode of binding. Diorganotin(IV) derivatives (<b>2</b> and <b>3</b>) generally exhibited poor antibacterial/antifungal potential as compared to their trialkyltin(IV)/triaryltin(IV) counterparts (<b>5</b> and <b>6</b>). The <i>in vitro</i> hemolytic activities show that average lysis of human red blood cells caused by <b>1</b>–<b>7</b> was significantly lower compared to triton X-100 (positive control, 100% lysis) and not very much higher than PBS (negative control, 0% lysis).</p