Modulation of Magnetic Behavior and Hg²⁺ Removal by Solvent-Assisted Linker Exchange Based on a Water-Stable 3D MOF

Abstract

SC–SC solvent-assisted linker exchange (SALE) in MOF materials is of high interest due to the potential applications. In this work, we reported an efficient transformation via SALE in a water-stable 3D MOF ({[Ni1.5(L)(4,4′-azobpy)(H2O)]·6.5H2O}n (1)) (H3L = 1-aminobenzene-3,4,5-tricarboxylic acid). The reaction progress of SALE was monitored and proved by single crystal XRD, PXRD and UV–vis absorption analyses, and the structural integrity of progeny MOFs {[Ni1.5(L)(4,4′-bpy)(H2O)]·6H2O}n (2), {[Ni1.5(L)(bpe)(H2O)]·8.5H2O}n (3), and {[Ni1.5(L)(NH2-bpy)(H2O)]·7.5H2O}n (4) were maintained very well, which is rarely in reported MOF materials. Theoretical calculations and the analyses of core–shell crystals give us better understanding of the exchange process. Interestingly, MOFs 2 and 3 obtained by SALE methods showed the different magnetic behavior comparing to parent MOF 1. Especially, because of the functional −NH2 group, progeny MOF 4 displayed the good capability to remove Hg2+ ions with an adsorption capacity of 93.693 mg/g. This work provides a new way to develop multifunctional MOF materials.