A New Zinc-based Metal Organic Framework as a Stationary Phase for Thin Layer Chromatography

Abstract

Metal organic frameworks (MOFs) are a variety of micro-porous materials which have high surface area, and permanent porosity making them possible options as chromatographic stationary phases. Herein we reported the synthesis and characterization of a new MOF structure and its utilization as a stationary phase for thin layer chromatography (TLC). [Zn(BMAB).DMF]n is a zinc-based MOF with an organic linker consists of chemically distinct binding groups which is 4-{[(1h-1,2,3-benzotriazol-1-yl)methyl]amino}benzoic acid (BMAB). This MOF was synthesized using ultra sound assisted reaction process, then activated via solvent exchange protocol to preserve its porous structure. FT-IR, UV-diffuse reflection spectroscopy (UV-DRS) and differential scanning calorimetry (DSC) were performed to characterize the synthesized MOF. Integrated data from "loss on desolvation" and atomic absorption spectrophotometry (AAS) measurements were used to define the chemical composition of the synthesized material. A specific surface area of 122.9 m2/g was determined for the activated MOF using methylene blue langmuir isotherm method. TLC plates were prepared from the activated form of the structure to investigate its chromatographic characteristics by utilizing it to separate a model mixture of benzidine and o-tolidine using n-propanol: Chloroform: Acetonitrile (50:30:20, v/v/v) as a mobile phase. The retardation factors (Rf), separation factor, and resolution (Rs) were determined via densitometric method at 310 nm to be 0.45 and 0.63 (α=2.08, Rs=1.61) for o-tolidine and benzidine; respectively. The plate was then visualized using iodine chamber method to confirm a successful separation.