1-(3-Chlorophenyl)-4-(3-phenylseleno propyl) piperazine (L); synthesis, spectroscopic characterization, DFT studies, antimicrobial evaluation and its reactivity toward group 12 metal chlorides
<p>C<sub>6</sub>H<sub>5</sub>Se<sup>−</sup>Na<sup>+</sup> (generated <i>in situ</i> by NaBH<sub>4</sub> reduction of (C<sub>6</sub>H<sub>5</sub>Se)<sub>2</sub>) on reaction with ClC<sub>3</sub>H<sub>6</sub>C<sub>4</sub>H<sub>8</sub>N<sub>2</sub>ClC<sub>6</sub>H<sub>5</sub> under N<sub>2</sub> atmosphere results in C<sub>6</sub>H<sub>5</sub>SeC<sub>3</sub>H<sub>6</sub>C<sub>4</sub>H<sub>8</sub>N<sub>2</sub>ClC<sub>6</sub>H<sub>5</sub> (L) as a cream-colored solid. Its 1:1 metal complexes having the general formula [MLX<sub>2</sub>], where M = Zn, Cd, Hg, and X = Cl, have been prepared. Ligand L and its complexes <b>1–3</b> are characterized on the basis of physico-chemical and spectral (FT-IR, ESI Mass, <sup>1</sup>H, <sup>13</sup>C, DEPT 135° <sup>13</sup>C {<sup>1</sup>H}, and <sup>77</sup>Se{<sup>1</sup>H} NMR) studies. IR spectroscopy revealed that L is coordinated solely through selenium and nitrogen to zinc, cadmium, and mercury ions forming a six-membered chelate ring around M(II) ions. Elemental analysis measurements along with <sup>1</sup>H, <sup>13</sup>C, DEPT 135° <sup>13</sup>C {<sup>1</sup>H}, and ESI-mass data also confirm the bidentate coordination mode of the ligand. Moreover, the coordination from selenium atom is also supported by the downfield shift of signal in <sup>77</sup>Se{<sup>1</sup>H} NMR spectroscopy. Using DFT-based optimization of structures, the HOMO-LUMO energy gaps and molecular electrostatic potential surface of ligand L and complexes <b>1–3</b> were theoretically calculated at the B3LYP/LANL2DZ level of theory. Ligand L and complexes <b>1–3</b> display significant antibacterial and antifungal activity.</p
