Dual-responsive luminescent sensitivities of a 3D Co-CP with turn-on and ratiometric sensing toward ascorbic acid and turn-off detecting acetylacetone

By selecting the luminescent tricarboxylate ligand H3L, a novel 3D Co(II)-based coordination polymer (compound 1) with the formula [Co(HL) (bpe)] (H3L = 5-(3,4-dicarboxylphenoxy) nicotic acid; bpe = 1,2-bis(4-pyridyl) ethylene) has been solvothermally synthesized, which features a 2-nodal (3, 5)-connected net with the Schlafli sign of (6(3).6(9).8). Particularly, it is found that compound 1 possesses good chemical and thermal stability. Luminescence measurements indicate that this material shows rare ratiometric turn-on luminescence response toward ascorbic acid (AA). The relative luminescent intensity ratio (I-362/I-410) increases linearly with increasing AA concentration in the 0-25 mu M range with detection limit of 0.68 mu M. Compound 1 could also respond to acetylacetone through luminescence turn-off mechanism. The limit of detection is estimated to be 1.35 mu M. Both proposed sensing systems show good sensitivity, high selectivity and excellent anti-interference performance. In addition, the possible sensing mechanisms are also elaborately investigated.