A multifunctional probe based on a heterometallic-organic framework: highly selective detection of 1,3-dinitrobenzene, tryptophan, and visual recognition of pentavalent vanadate ions

Herein, a novel luminescent heterometal-organic framework (HMOF), {[EuZn2(imdc)2(4,4′-bpy) (H2O)4(OH)]·4,4′-bpy}n (1), was synthesized by selecting d-f heterometals and two ligands with abundant coordination sites (H3imdc = 1H-imidazole-4, 5-dicarboxylic acid, 4, 4′-bpy = 4, 4′-bipyridine). The X-ray single crystal diffraction reveals that compound 1 is a three-dimensional framework structure with two kinds of channels, which has good pH fluorescence stability. Compound 1 is demonstrated to be the first known HMOF for selective detection of pentavalent vanadate ions (VO43− or VO3−). It also exhibited high selectivity, sensitivity, and low detection limits for 1,3-dinitrobenzene (1, 3-DNB) and L-tryptophan (L-Trp). More significantly, the portable MOF-based fluorescent paper of compound 1 was also successfully manufactured and might be potentially used as a functional material with naked eye recognition. Furthermore, the fluorescence mechanisms of compound 1 for sensing the above analytes have been elaborated in detail.