A novel 2D nickel coordination polymer based on Trimesic acid with glyphosate coordination capabilities

Abstract

Abstract This work presents the synthesis and characterization of a novel coordination polymer entitled Ni-BTC, using nickel as metallic centers and Trimesic Acid (H₃BTC) as linkers. This new structure was characterized using Single Crystal X-ray Diffraction (SCXRD), exhibiting a MOF (metal–organic framework) structure, with a minimal formula of {[Ni(HBTC)(DMF)₂]·xDMF}. The structure exhibits a 2D network expanding in the equatorial direction, where the Ni(II) center is hexacoordinated and N,N'-dimethylformamide (DMF) solvent molecules are coordinated along the axial axis. Additionally, a Co-BTC coordination polymer was synthesized, with an already known structure similar to Ni-BTC, given the coordination modes of the BTC and DMF ligands. The structure of Ni-BTC is also a pseudo-polymorph of the previously published MOF [Ni(HBTC)(DMF)₂·(guest)] (3). The crystallographic data illustrate the structural differences. Ni-BTC was also analyzed by Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (FESEM-EDS), revealing two different phases, one containing chloride anions originating from the precursor salt NiCl₂∙6H₂O. Upon substitution of this precursor with Ni(NO₃)₂∙6H₂O, only one phase was observed, indicating the influence of the counter-ion in modulating new phases during synthesis. Ni-BTC was further characterized by thermal methods such as Thermogravimetric Analysis and Differential Thermal Analysis (TGA and DTA), showing moderate thermal resistance. The Magnetic Susceptibility data indicated a + 2 state for both metal centers. Finally, the bidentate molecule Glyphosate (GLY), widely used as a pesticide and recognized as an environmental pollutant, was employed for coordination with Ni-BTC, as in this structure, the axial DMF ligands are labile and can be replaced by glyphosate molecules. This coordination capability was demonstrated by Powder X-ray Diffraction (PXRD) and Infrared Spectroscopy (FTIR), along with electrochemical techniques such as Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV), thus confirming glyphosate coordination in Ni-BTC, with potential applications in detection and removal systems. Graphical Abstract