A Chiral Proline Functionalized γ-Octamolybdate Based Coordination Polymer: Structural and Biological Insights

Abstract

A new inorganic–organic hybrid based on proline functionalized γ-octamolybdate, [Co 2 (H 2 O) 6 (C 5 H 9 NO 2 ) 2 (Mo 8 O 26 )]·2H 2 O ( 1 ) has been synthesized under hydrothermal conditions from the reaction of an Evans–Showell-type polyoxometalate, (NH 4 ) 6 [Co 2 Mo 10 H 4 O 38 ], and proline. Characterization by IR spectra, elemental analysis, solid diffuse reflective spectrum (DRS) and single crystal X-ray diffraction revealed that 1 is a coordination polymer. Compound 1 undergoes a disorder under hydrothermal conditions. This is due to changes in the bond lengths and bond angles in IPA and proline ligands compared to the non-disordered state. As a result, the molecule loses its symmetry and in the molecular state and in the crystalline phase, a chiral structure was obtained. The structure of proline allows the cobalt ion to not only have a covalent interaction with proline via the carboxyl group of proline, but also to act as a linker between two isoples, leading to a covalent chain. then adjacent 1D chiral chains joined together by another Co-O covalent interactions to yield a 2D supramolecular chiral layer. The topology of 1, can be rationalized as a two dimensional square lattice ( sql ) coordination network with point symbol {4 2 .6 4 } 2 {4 8 .6 6 .8} in which, [Mo 8 O 26 (C 5 H 9 NO 2 ) 2 ] 4− units act as nodes and the Co cations as linkers. Although, proline ligands have no direct role in expanding the structure as a 2D covalent polymer. Also, the anti-cancer activity of compound 1 was evaluated to determine the IC 50 values against two human-derived colon cancer and normal fibroblast cells. The compound 1 exhibited both concentration- and time-dependent anti-proliferative effects on the cancerous cells.