Series d–f Heteronuclear Metal–Organic Frameworks: Color Tunability and Luminescent Probe with Switchable Properties

A series of five unique d–f heteronuclear luminescent metal–organic frameworks (MOFs) in an entangled polyrotaxane array and the light-harvesting block homonuclear zinc compound have been isolated successfully and characterized. The series of isostructural polymers feature 3,4-connected (4.8 2 )(4.8 3 .9 2 )(6.8.9) 2 (6.9 2 )(8 3 ) topology and high stability, exhibiting diverse void spaces. By taking advantage of the isostructural MOFs 2 and 3, the intensities of red and green emissions can be modulated by adjusting the ratios of Eu III and Tb III ions correspondingly, and white-light emission can be generated by a combination of different doped Tb III and Eu III concentrations. The Tb–Zn-based framework {[Tb 3 Zn 6 (bipy 2 ) 2 (Hmimda) 7 (H 2 O) 3 ]·5H 2 O} n ( 3; H 3 mimda = 2-methyl-1- H -imidazole-4,5-dicarboxylic acid and bipy = 4,4′-bipyridine) can detect trace Mg II ion with relatively high sensitivity and selectivity. Dehydrated MOF 3a shows a remarkable emission quenching effect through the introduction of I 2 solids. Further investigation indicates that it exhibits turn on/off switchable properties for small solvent molecules or heavy-metal ions. Steady/transient-state near-IR luminescence properties for MOFs 1, 4, and 5 were investigated under visible-light excitation.