Expanding the NUIG MOF family: synthesis and characterization of new MOFs for selective CO2 adsorption, metal ion removal from aqueous systems, and drug delivery applications

Abstract

Metal organic frameworks (MOFs) have attracted considerable attention in recent years due to their use in a wide range of environmental, industrial and biomedical applications. The employment of benzophenone-4,4′-dicarboxylic acid (bphdcH₂) in MOF chemistry provided access to the 3D mixed metal MOFs [CoNa₂(bphdc)₂(DMF)₂]_n (NUIG2) and [ZnK₂(bphdc)₂(DMF)₂]_n (NUIG3), and the 2D homometallic MOF [Co₂(OH)(bphdcH)₂(DMF)₂(H₂O)₂]_n(OH)·DMF (1·DMF). 1·DMF is based on a dinuclear SBU and consists of interpenetrating networks with an sql topology. Dc magnetic susceptibility studies were carried out in 1·DMF and revealed the presence of weak antiferomagnetic exchange interactions between the metal centres. NUIG2 and NUIG3 are structural analogues of [ZnNa₂(bphdc)₂(DMF)₂]_n (NUIG1), which has shown an exceptionally high encapsulation for ibuprophen (Ibu), NO and metal ions. Both NUIG2 and NUIG3 display high metal ion (Co^II, Ni^II, Cu^II) adsorption capacity, comparable to that of NUIG1, with NUIG2 exhibiting good performance in Ibu uptake (780 mg Ibu per g NUIG2). Monte Carlo simulations were conducted in NUIG1 in order to assess its adsorption capacity for other guest molecules, and revealed that it possesses an outstanding CO₂ uptake at ambient pressure, which is larger than that of the previously reported best functioning species (104 vs. 100 cm³ (stp) per cm³). Furthermore, NUIG1 exhibits high selectivity for CO₂ over CH₄.