Triazole-Based Cu(I) Cationic Metal-Organic Frameworks with Lewis Basic Pyridine Sites for Selective Detection of Ce Ions.

A highly symmetric bis-triazole-pyridine-based organic ligand, i.e., 3,5-di(4-1,2,4-triazol-4-yl)pyridine (), and Cu(II) salts were used to synthesize three cationic Cu(I) metal-organic frameworks (MOFs), namely, {[Cu(L)]·(NO)·(HO)} (), {[Cu(L)]·(BF)·0.5HO} (), and {[Cu(L)]·1.25(ClO)·HO} (). All three MOFs have nonbonded anions situated inside the pore spaces. Both and have a two-dimensional network structure, while has a three-dimensional structure. All three MOFs were characterized using Fourier transform infrared spectroscopy, elemental (C, H, and N) analysis, thermogravimetric analysis, and powder and single-crystal X-ray diffraction. Due to the presence of a Lewis basic pyridine moiety, these MOFs could serve as luminescent probes for the selective detection of Ce ions with excellent efficiency (10 M). The synthesis of Cu(I)-based MOFs and their use to detect Ce ions in water via a turn-on fluorescence process have rarely been reported. These MOFs are highly stable in water, are recyclable, and function efficiently at different pH values.