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.
Background: Many amino acids and their derivatives have been used previously as chiral selectors in thin layer chromatography. Herein, we reported the synthesis, characterization, and chromatographic evaluation of a new modified stationary phase based on (S)-3-(aminomethyl)-5-methylhexanoic acid (also known as pregabalin) as an amino acid ligand bonded to the silica surface via triazine attachment. Results: SC-2P (silica-cyanuric-2-pregabalin) is a bonded silica stationary phase prepared by direct binding of the pre-synthesized cyanuric-2-pregabalin organic ligand on the chlorinated silica surface. FT-IR and UV diffuse reflection spectroscopy (UV-DRS) were used to characterize the synthesized bonded phase, and the specific surface area was determined using the methylene blue Langmuir isotherm method to be 147.04 m 2 /g. TLC plates were prepared from a slurry of this synthesized material with 2 mM of Cu 2+ as a selector additive, and the chromatographic characteristics of these plates were investigated to separate a ternary mixture of o-, m-, and pnitrophenol as structural isomers, and a racemic mixture of (±)-ibuprofen as stereoisomers. Solvent systems of nhexane:dichloroethane:n-propanol (75:20:5, v/v/v) and Dichloroethane:acetonitrile (90:10, v/v) were selected as mobile phases for nitrophenol and ibuprofen mixtures, respectively. The successful separation was densitometrically confirmed, and retardation factors (R f) were determined for o-, m-, and p-nitrophenol at 320 nm to be 0.83, 0.45, and 0.28, and for R(−)-, S(+)-ibuprofen at 220 nm to be 0.43 and 0.63, respectively. Conclusion: The synthesis, characterization, and chromatographic evaluation of SC-2P were reported in this article. SC-2P was used with copper ions to form in situ ligand exchange reagent (LER), which was successfully employed to solve an isomeric mixture of nitrophenol and a racemic mixture of (±)-ibuprofen. The synthesized stationary phase showed high repeatability with minimum R f shifts between batches.
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