Synthesis and Characterization of Novel Selenium Bearing 24- and 28-Membered Macrocyclic Schiff Bases and Their Reactivity with Hg (II) Ion

The present study reports the synthesis of novel selenium containing 24 (1)- and 28 (2)-membered macrocyclic Schiff base ligands and their reactivity with Hg(II) metal ion to form complex 3 and 4, respectively. The synthesis of the ligands are carried out by a simple condensation of 2,6-dibenzoyl-4-methylphenol and bis(aminoethyl/propyl)selenides in [2+2] dipodal manner in dry acetonitrile solvent under inert atmosphere. Furthermore, the reaction between the 24- and 28-membered selenium containing ligands and Hg(II) metal ion are carried out in dry methanol in argon atmosphere. Following the complexation of both the ligands, 1 (C₅₀H₄₈O₂N₄Se₂) and 2 (C₅₄H₅₆O₂N₄Se₂) when reacted with HgBr₂ yields monometallic complexes 3 and 4 with molecular composition of C₅₀H₅₀O₃N₄Se₂HgBr₂ and C₅₄H₅₈O₃N₄Se₂HgBr₂, respectively, as calculated via elemental analysis and mass spectrometry. Moreover, the synthesized compounds are also characterized by various physicochemical techniques to determine the structure and reactivity, which includes UV–vis, FT-IR, multinuclear (¹H and ⁷⁷Se) NMR, and cyclic voltammetry.