A highly efficient luminescent MOF-based TNP sensor fabricated by new AIE ligand

Abstract

Designing and synthesizing functional metal–organic frameworks (MOFs) remains great challenges. In this study, a new aggregation-induced-emission (AIE) molecule 4,4′-(((9H-fluoren-9-ylidene)methylene)bis(4,1-phenylene))dipyridine (L) was developed as functional ligand to construct a unique MOF [Cu(I)2Cu(II)L2(SCN)4]n (1) with mixed-valence Cu centers. 1 is fabricated by 4-connected Cu(II) and Cu(I) building units, and “V” shaped L and linear SCN− bridges, and forms a three-dimensional (3-D) binodal (4, 4)-connected framework with rare non-interpenetrated (64·82)(66)2 network. 1 demonstrates excellent water, pH and thermal stabilities, and can efficiently detect TNP in aqueous medium. Its quenching constant and detection limit for sensing TNP reach 2.16 × 105 M−1 and 1.05 × 10−5 mM, respectively, which are better than those of the most MOF-based TNP sensors. Moreover, 1 exhibits notable TNP sensing selectivity and recyclability. The luminescence quenching sensing mechanism of 1 toward TNP is in-depth investigated.