A multifunctional Tb-MOF constructed with triphenylamine-based hexacarboxylate ligands for highly luminescent sensing toward antibiotics and salicylaldehydes

Abstract

Antibiotics and salicylaldehydes are major organic pollutants in the environment, and their efficient selection and sensitive detection are of great significance but also challenging. A multifunctional terbium-organic framework (Tb-MOF) with multiple π-conjugated rings and basic sites decorated nanoporous channels was constructed with triphenylamine-based hexacarboxylate ligands. Structure analysis of Tb-MOF revealed that the six carboxyl groups on the skeleton of ligand exhibit considerable degree of distortion and can be regarded as three triangular nodes, which further combined the binuclear [Tb₂(COO)₆(H₂O)₄] nodes to form a new (3,3,3,6)-connected 3D net. Importantly, Tb-MOF provided the first example of luminescent MOFs constructed from triphenylamine-based hexacarboxylate ligands with multi-responsive behavior toward antibiotics and salicylaldehydes. Tb-MOF demonstrated excellent performance on the selection and recognition of two antibiotics, metronidazole (MDZ) and dimetridazole (DTZ), with the detection limit (LOD) of 0.60 and 0.95 μM, respectively. More importantly, Tb-MOF can achieve highly sensitive detection of three aldehydes, salicylaldehyde (SA), 5-methylsalicylaldehyde (5-MeSA) and 5-chlorsalicylaldehyde (5-ClSA), with LODs up to 0.58, 0.59 and 0.48 μM, respectively. Regenerated experiments indicated that Tb-MOF can be employed for the efficient detection of MDZ and SA at least five times. Thus, Tb-MOF can be potentially explored as a promising sensor to simultaneously identify antibiotics and salicylaldehydes in chemical detection and biologic environments with ultra-sensitivity, low LODs and extraordinary recycling capacity.