Multiple Interpenetrating Metal-Organic Frameworks with Channel-Size-Dependent Behavior for Selective Gossypol...

An interpenetrating structure endows metal-organic frameworks (MOFs) with many exciting applications, such as fluorescence detection and host-guest chemistry. Herein, two unique structure-interpenetrating In-MOFs (In-pdda-1 and In-pdda-2; H₂pdda = 4,4'-(pyridine-2,5-diyl)dibenzoic acid) are constructed by different coordination configurations. The four-connected In³⁺ center shows a triangular-pyramidal configuration or a 2D rectangle, forming an unc topology for In-pdda-1 and a sql network for In-pdda-2, respectively. Two different interpenetrating modes created by linear rigid ligands and metal clusters are observed in the two MOFs (In-pdda-1, 8-fold interpenetrating mode; In-pdda-2, [2D + 2D] interpenetrating mode), which determine the channel-size-dependent properties in fluorescence applications. During the quantitative detection process of gossypol, the small rhombic channels divided by interpenetrating molecular planes of In-pdda-2 greatly limit the distance between the analyte and the probe, promoting electron transfer and energy transfer processes and thus resulting in a low detection limit (28.6 nM). In addition, the pore size effect of In-pdda-1 encouraged us to explore an in situ perovskite quantum dot encapsulation strategy to obtain a MAPbBr₃@MOF material with tunable and stable luminescence properties. Both of the above channel-size-dependent fluorescence properties may provide inspiration for the structural design and specialized applications of MOF materials.