Interpenetrated metal-organic frameworks with enhanced photoluminescence for selective recognition of m -xylene from xylene isomers.

Two novel luminescent metal-organic frameworks (MOFs), [Zn 3 (TCA) 2 (BPB) 2 ] n (DZU-101, where H 3 TCA = 4,4',4''-tricarboxyltriphenylamine and BPB = 1,4-bis(pyrid-4-yl)benzene) and [Zn 3 (TCA) 2 (BPB)DMA] n (DZU-102), based on the same ligands and metal ions were synthesized by regulating the amount of water in the solvothermal reaction system. Structural analyses show that the two MOFs have pillar-layered frameworks with Zn 3 clusters connected by the TCA 3- and BPB ligands. Interestingly, DZU-102 possessed a two-fold interpenetrated framework distinct from the individual network of DZU-101. As a result, DZU-102 showed a visual fluorescence color change from chartreuse to azure in m -xylene, while the fluorescence color was turquoise in p -/ o -xylene with no change. Furthermore, compared with p / o -xylene, the fluorescence emission peak of DZU-102 in m -xylene suspension produced an obvious blue shift. Moreover, selective fluorescence sensing experiments were also carried out, which demonstrated that the degree of peak shift was related to the concentration of m -xylene, indicating the potential application of DZU-102 in fluorescence sensing of m -xylene from xylene isomers and further revealed the application of structural interpenetration for luminescence tuning of MOFs.