Synthesis of a tetrazine-based catecholamide derivative and its evaluation as a chelating agent for removal of Cd(II), Co(II), and Cu(II)

<p>The synthesis and structural characterization of a tetrazine-based catecholamide (CAM) ligand, <i>N,N′</i>-bis(<i>N″</i>-(aminoethyl)-2,3-bis(hydroxy)benzamide)-1,2,4,5-tetrazine-3,6-diamine (<b>5</b>), were investigated. All compounds were characterized by <sup>1</sup>H NMR spectroscopy, <sup>13</sup>C NMR spectroscopy, and FTIR spectroscopy. The protonation equilibria of <b>5</b> and complexation capacities (log <i>β</i><sub>pqr</sub>) of Cd<sup>2+</sup>, Co<sup>2</sup><sup>+</sup>, and Cu<sup>2+</sup> complexes of <b>5</b> were evaluated through potentiometric titration and spectrophotometric titration, respectively. Species independent pM value (=−log [M]<sub>free</sub>) was used to compare metal affinities with the final sequence Cu<sup>2+</sup> > Cd<sup>2+</sup> > Co<sup>2+</sup>. Results show that <b>5</b> has potential for heavy metal removal.</p>