Functionalization of a porous copper(ii) metal-organic framework and its capacity for loading and delivery of...

A porous copper(ii) metal-organic framework (MOF) of 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine(N₃ttb) and 5-nitroisophthalic acid (npd) formulated as [Cu(npd)(N₃ttb)]·(DMF)(H₂O) 1 (DMF = dimethylformamide) was synthesized and characterized by elemental analyses, spectroscopic techniques, single crystal X-ray crystallography, and scanning electron microscopy. Single crystal X-ray crystallographic analysis of the copper(ii) metal-organic framework reveals a monoclinic crystal system with space group P2₁/c. The copper(ii) ion is in a five-coordinate geometry consisting of three meridional nitrogen atoms of 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine and two oxygen atoms of 5-nitroisophthalic acid to form a square pyramidal structure. The compound was functionalized with ethylenediamine (ED) to form [Cu(npd)(N₃ttb)]-ED 2 that was characterized by FT-IR, PXRD, SEM-EDX and BET and the drug loading capacity was investigated and compared with that of as-synthesized MOFs. The amount of ibuprofen loaded was 916.44 mg g^-1 (15.27%) & 1530.20 mg g^-1 (25.50%) over 1 and 2, respectively. The results indicate that the functionalized MOFs 2 have a higher loading capacity for ibuprofen than 1 by 613.76 mg g^-1 (10.23%), which could be ascribed to the acid-base interactions in the functionalized molecules. The results show that [Cu(npd)(N₃ttb)]-ED 2 is a better drug transporter than [Cu(npd)(N₃ttb)]·(DMF)(H₂O) 1 due to the presence of an amine functional group that interacts with the acid group on the ibuprofen through non-covalent bonds interactions.