Self‐assembly of unexpected [Mn(2‐(1‐hydrazonoethyl)pyridine)Cl₂]_n 1D coordination polymer: Synthesis, structural elucidation, and biological studies

Abstract

Self-assembly of (((1-(pyridin-2-yl)ethylidene)hydrazono)methyl)phenol ligand (L 1 ) and MnCl 2 proceeded with the hydrolysis of the ligand affording the new [Mn(L 2 )Cl 2 ] n 1D coordination polymer where L 2 is 2-(1-hydrazonoethyl)pyridine. The structure of [Mn(L 2 )Cl 2 ] n was confirmed using FTIR, CHN, and Xray diffraction of single crystal. It crystallized in the triclinic P-1 crystal system with a = 7.0697(9) Å, b = 8.878(1) Å, c = 9.402(2) Å, α = 113.99(2) , β = 95.48(1) , γ = 111.77(1) , and V = 479.13(15) Å 3 . The Mn(II) is octahedrally coordinated with two nitrogen atoms from L 2 and four chloride ions. The chloride anions act as bridging ligand that connect the Mn(II) centers leading to the formation of the 1D polymer. Based on continuous shape (CShM) measure tool, the coordination configuration is closer to the octahedron rather than a trigonal prism. Using Hirshfeld analysis, the Cl … H (29.2%), H … C (13.6%), and C … C (3.7%) contacts are the most important in the molecular packing of [Mn(L 2 )Cl 2 ] n complex. The ligand L 2 has better antibacterial, antifungal, and antioxidant activities than the Mn(II) complex. The [Mn(L 2 )Cl 2 ] n complex has higher cytotoxic effect than L 2 against both lung carcinoma A-549 and lung fibroblast MRC-5 cell lines. The IC 50 and CC 50 values of the Mn(II) complex are 26.09 ± 1.76 and 60.40 ± 3.74 μg ml À1 , respectively, while 121.23 ± 5.91 and 241.13 ± 13.29 μg ml À1 , respectively, for L 2 . K E Y W O R D Santi-cancer agent, hydrazone, Mn(II) complex, Schiff bases, self-assembly | INTRODUCTIONSchiff bases are compounds generated from the reaction of aldehydes or ketones with compounds carrying amino group. These compounds are being significantly consumed as ligands for the production of numerous types of metal complexes. [1][2][3] Schiff bases and their complexes are known to have interesting catalytic and biological activities. The activity is influenced by complexation of the Schiff base ligand with metals, which can result in the synthesis of new different compounds with several applications in the chemical industry, for both organic synthesis and the pharmaceutical industry. [4][5][6][7][8] Recently, significant attention has been given to arylhydrazone Schiff base ligands since they contain a range of donor atoms that give them a unique potential to bind