A Ni-Based Metal-Organic Framework with Polarizing Traits for Efficient Heterogeneous Catalysis in the Sustainable Synthesis of Oxazolidinones

In this study, a Ni-based metal-organic framework (MOF), Ni-MOF, was synthesized from a mixture of Ni(OAc)2 & sdot; 4H2O, a dicarboxylate, 4,4'-(1,3,4-oxadiazole-2,5-diyl)dibenzoate (oxdz2-), and a bis(tridentate) ligand, (N,N',N'',N'''-tetrakis(2-pyridylmethyl)-1,4-diaminoxylylene) (tpxn), under ambient conditions using greener solvents in 12 h. The framework was well-characterized using several analytical techniques. The highly crystalline Ni-MOF exhibited remarkable polarizing traits with significant uptake of CO2 and water vapor up to 10.53 cm3 g-1 and 290 cm3 g-1, respectively, at 298 K. The isosteric heat of adsorption between Ni-MOF and CO2 at zero loading was calculated to be 32.43 kJ mol-1. Furthermore, utilizing its CO2-philic and catalytic features, Ni-MOF was employed as an excellent heterogeneous catalyst (2.5 mol%) along with very low concentration of TBAB (0.02 mmol) as a co-catalyst for the synthesis of oxazolidinones via a standard three-component reaction among an epoxide, a substituted aniline, and carbon dioxide under solvent-free conditions. A wide range of oxazolidinones including three bioactive derivatives was synthesized using both diverse epoxides and aniline derivatives to demonstrate the substrate scope. The catalyst was proved to be recyclable, reusable, and stable for multiple cycles, without leaching of the metal from it. The mechanistic insights revealed that Ni-MOF polarizes all three reactants to catalyze the oxazolidinone formation. A Ni-based metal-organic framework (Ni-MOF) was synthesized through an efficient three-component approach using Ni2+ ion, oxadiazole-based dicarboxylate, and neutral bis(tridentate) pyridyl ligand. The reaction was scaled up for easy work-up, yielding several grams, due to its ambient synthesis in greener solvents. The polarizing traits of Ni-MOF were utilized to synthesize bioactive oxazolidinones and other derivatives in a sustainable, solvent-free environment. image