Heterometallic Alkaline Earth-Lanthanide Ba-II-La-III Microporous Metal-Organic Framework as Bifunctional Luminescent Probes of Al3+ and MnO4-

摘要

In this work a rigid asymmetrical tricarboxylate ligand p-terphenyl-3,4",5-tricarboxylic acid (H3L) has been employed, and a unique heterometallic alkaline earthlanthanide microporous luminescent metalorganic framework (MOF) {[Ba3La0.5(mu 3-L)(2.5)(H2O)(3)(DMF)].(3DMF)}(n) (1.3DMF) (DMF = dimethylformamide) has been isolated under solvothermal conditions. Single-crystal x-ray structural analysis demonstrates that 2D inorganic Ba-O-La connectivity can be observed in 1, which are further bridged via rigid terphenyl backbones of L3-, forming a unique I2O1-type microporous luminescent framework. A 1D microporous channel with dimensionality of 9.151(3) angstrom x 10.098(1) angstrom can be observed along the crystallographic a axis. PxRD patterns have been investigated indicating pure phases of 1. The luminescence explorations demonstrated that 1 exhibits highly selective and sensitive sensing for Al3+ over other cations with high quenching efficiency Ksv value of 1.445 x 10(4) L.mol(1) and low detection limit (1.11 mu M (S/N = 3)). Meanwhile 1 also exhibits highly selective and sensitive sensing for MnO4 over other anions with quenching efficiency Ksv = 7.73 x 103 L.mol(-1) and low detection limit (0.28 mu M (S/N = 3)). It is noted that, when different concentrations of MnO4- solutions (0.5 to 100 mu M) were dropped into the suspension of 1, the bright blue luminescence of the suspension observed under UV light can gradually change into pink color, indicating visually luminescent sensing, which makes the detection process of MnO4- more convenient in practical. The result also reveals that 1 represents the first example of bifunctional heterometallic alkaline earth-lanthanide MOF-based luminescent probes for selectively detecting Al3+ and MnO4- in the water solutions.