Four Novel Lanthanide(III) Metal–Organic Frameworks: Tunable Light Emission and Multiresponsive Luminescence Sensors for Vitamin B<sub>6</sub> and Pesticides
X. Wang, Xuehui Ma, Doudou Feng, Jing Tang, Dan Wu, Jie Yang, Jingjing Jiao
Abstract
Four novel lanthanide(III)-based metal–organic frameworks (MOFs), formulated as [Ln3(HDDB)(DDB)(H2O)6]·NMP·3H2O (Ln = Eu (1), Tb (2), Dy (3), Gd (4)), were successfully constructed with a rigid pentacarboxylate ligand 3,5-di(2′,4′-dicarboxylphenyl) benzoic acid (H5DDB). Complexes 1–4 are isostructural and exhibit a new 3,4,4,6-connected network. 1–2 exhibit excellent fluorescence properties and good water stability. The emissions of the doped bimetallic EuxTb1–x-MOFs can be adjusted by varying the Eu(III)/Tb(III) ratios used in the reaction. Furthermore, 2 presents excellent sensitivity and selectivity to sense vitamin B6 (VB6) and the pesticide 2,6-dichloro-4-nitroaniline (DCN) as a multiresponsive luminescent sensor. Compound 2 is the first MOF-based luminescent sensor for detecting VB6 with a low detection limit (LOD) of 9.5 × 10–8 M (∼58.4 ppb) in phosphate buffer solution (pH = 6.86), which also displays a high-sensitivity sensing activity for VB6 in human serum. Moreover, 2 exhibits high-sensitivity sensing for the pesticide DCN with an LOD value of 1.4 × 10–7 M (∼86.1 ppb) in aqueous solution, and it also can be successfully used for detecting DCN in the extracts of carrots, grapes, and nectarines.