Synthesis and Structural Characterization of MOF-5 – a metal-organic compound based on Zn(II) and terephthalate anions

Abstract

Metal-Organic Frameworks (MOFs) are porous hybrid crystalline materials highly prized for their customizable architectural frameworks. This study focuses on the synthesis and optimization of MOF-5, a landmark Zn(II)-based coordination polymer, evaluating how solvothermal reaction durations impact structural stability and subsequent chemical remediation capabilities. Methods: MOF-5 was synthesized solvo-thermally using zinc nitrate hexahydrate and terephthalic acid in N,N-dimethylformamide (DMF) at 120°C across varying crystallization intervals (18 h, 24 h, and 48 h). Crystalline validation was completed via Fourier-Transform Infrared (FTIR) spectroscopy and Thermal Analysis (TG/DTG/DTA). Environmental trapping capacity was systematically quantified through the fluid-phase adsorption of molecular iodine (I₂) and Methylene Blue (MB) dye, monitored via Raman and UV-Vis spectrophotometry. Results: FTIR and thermogravimetric data verified that a 24-hour reaction window yields an optimized, highly ordered lattice framework with low residual host solvent entrapped in the pores. Prolonged heating to 48 h caused framework deterioration. Raman profiles verified successfully trapped iodine guest species, yielding distinctive polyiodide peaks (~80–130 cm⁻¹ and ~219 cm⁻¹) alongside ligand shift interactions. Kinetic UV-Vis trials confirmed rapid Methylene Blue remediation, stabilizing near 70 minutes before reaching an adsorption equilibrium. Conclusions: The synthesized MOF-5 matrices display strong physical capture dynamics for inorganic and organic water pollutants. However, structural vulnerability in continuous aqueous setups remains a critical threshold constraint for prolonged field applications.