Multiple Interpenetrating Metal–Organic Frameworks with Channel-Size-Dependent Behavior for Selective Gossypol Detection and Perovskite Quantum Dot Encapsulation

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.