A Doubly Interpenetrated Cu<sup>II</sup> Metal–Organic Framework for Selective Molecular Recognition of Nitroaromatics
Pooja Rani, Gauri, Ahmad Husain, K.K. Bhasin, Girijesh Kumar
Abstract
Herein, we report the design, synthesis, and structural characterization of a novel 2-fold interpenetrated CuII metal–organic framework Cu-MOF-1 [{Cu2(L)(oba)2}·DMF·H2O]α. A single-crystal X-ray analysis reveals that Cu-MOF-1 exhibits a doubly (1 + 1) interpenetrated three-dimensional structure with 6-connected mab topology. Moreover, Cu-MOF-1 showed high fluorescence stability in methanol solution and selectively detected nitroaromatics with high quenching constants and low detection limits of 0.31 × 105 M–1 and 22.65 μM for 2,4,6-TNP; 1.34 × 105 M–1 and 18.7 μM for 4-NPH; and 1.49 × 105 M–1 and 14.07 μM for 4-NA. Notably, ligand L itself did not display any type of recognition for any nitroaromatics in methanol solution. The sensing of NACs by Cu-MOF-1 followed mostly the resonance energy transfer mechanism; however, in the case of 4-NPH and 2,4,6-TNP an electron transfer mechanism also exists. Importantly, Cu-MOF-1 shows recyclability up to five cycles without any significant loss in quenching efficiency.