Solvent induced synthesis of fluorescence Zn(II)-based metal–organic frameworks with distinctive responsiveness to DMF stimuli

Two new luminescent MOFs, namely, {[Zn2(TCA)(BPPB)(DMA)(OH)]·2DMA}n (DZU-115), [Zn(HTCA)(BPPB)0.5(DMA)]n (DZU-116. DZU, H3TCA, BPPB is short for Dezhou University, 4,4′,4″-tricarboxyltriphenylamine and 4,4′-(9,10-anthracenediyl)bis-Pyridine, respectively), were successfully synthesized by solvent adjustment and characterized by single crystal X-ray diffraction. DZU-115 shows a fascinating three dimensional (3D) framework derived from the interlocking of 2D coordination dual-layers, while DZU-116 displays a different 2D layer structure. Due to the interpenetrated structure of DZU-115 that is in favor of the formation of interaction between the host frameworks and DMF molecules, a luminescent color transition from yellow-green to light orange has been found in DZU-115 when exposing the MOF to DMF solvent. Moreover, the DZU-115-based filter paper was also prepared, which is capable of producing visual changes in fluorescent color to identify DMF vapor. Remarkably, the color variation is highly reversible and the light orange color could be further converted back into yellow-green by immersing the material in DMA solvent again. Such a reversible stimuli-response behavior with the apparent luminescence color change indicates the potential application of the MOF as a recognition platform for DMF molecules. This study provides valuable insight into optimizing the performance of MOF by tuning the framework structures, and offers a promising avenue for the development of vapor molecule recognition materials