Tuning Chromophore-Based LMOF Dimensionality to Enhance Detection Sensitivity for Fe3+Ions

Abstract

Herein, we report the synthesis of two new manganese-based luminescent metal-organic frameworks (LMOFs) [Mn0.5(tipe)(1,4-ndc)]n (1) and [Mn(tipe)(1,4-ndc) (H2O)·(DMF)2·(H2O)3]n (2) [tipe = 1,1,2,2-tetrakis(4-(1H-imidazol-1-yl)phenyl)ethene (tipe) and 1,4-ndc = 1,4-naphthalenedicarboxylic acid] constructed from an aggregation-induced emission (AIE) chromophore ligand. Compound 1 can undergo a facile single-crystal-to-single-crystal transformation to form compound 2, which results in an increase in dimensionality from a two-dimensional (2D) network to a three-dimensional (3D) network. Both compounds demonstrate excellent performance for the solution-phase detection of Fe3+ ions through a significant and rapid quench in luminescence emission. Fluorescence titration experiments reveal that compound 2 is more selective toward Fe3+ compared to compound 1 because of its 3D stacking mode. The Ksv value for compound 2 (32 378 M-1) is twice as large as that for compound 1 (15 854 M-1) for the detection of Fe3+ ions. We attribute this significant increase in performance to the increase in dimensionality. In addition, compound 2 demonstrates high selectivity and sensitivity for the detection of Cr3+ cations and Cr2O72- anions.