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

Two novel luminescent metal-organic frameworks (MOFs), [Zn(TCA)(BPB)] (DZU-101, where HTCA = 4,4',4''-tricarboxyltriphenylamine and BPB = 1,4-bis(pyrid-4-yl)benzene) and [Zn(TCA)(BPB)DMA] (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 clusters connected by the TCA 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 -xylene, while the fluorescence color was turquoise in -/-xylene with no change. Furthermore, compared with /-xylene, the fluorescence emission peak of DZU-102 in -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 -xylene, indicating the potential application of DZU-102 in fluorescence sensing of -xylene from xylene isomers and further revealed the application of structural interpenetration for luminescence tuning of MOFs.