Metal-directed thiophene-carboxylate-based nickel(II) complexes as multifunctional electrochemical and fluorescent sensors for detecting different analytes

To investigate the effect of the sites of S-atoms in thiophene carboxylates on the structures of coordination polymers, two thiophene-mono-carboxylic acids (2-Htpc = thiophene-2-carboxylic acid and 3-Htpc = thiophene-3-carboxylic acid) and a fluorescent active semi-rigid amide [N,N′-bis(3-methyl pyridine-3-yl)-2,6-naphthalenediamide (L)] were selected to combine with electrochemically active metal ions of Ni(II), and two new coordination polymers (CPs), namely [Ni 0.5 (L) 0.5 (2-tpc)](H 2 O)]∙1.5H 2 O (1) and [Ni 0.5 (L) 0.5 (3-tpc)](H 2 O)]∙1.5H 2 O (2), were obtained through traditional hydrothermal methods. The single-crystal X-ray diffraction analyses of the two CPs show that there are similar zigzag chains with the crossed-stacking modes. The two CPs can act as multifunctional electrochemical sensors to detect NO 2 − , chloramphenicol, and L-ascorbic acid (AA) and fluorescent recognition of Fe 3+ and Cr 2 O 7 2− . The detection limits of 1 were 1.08 × 10 −6 , 1.18 × 10 −4 , and 1.06 × 10 −4 for AA, Fe 3+ , and Cr 2 O 7 2− . The corresponding values of 2 were 1.43 × 10 −6 , 2.06 × 10 −4 , and 2.06 × 10 −4 . Graphical abstract Two Ni(II) coordination polymers showing the same crossed-stacking modes display electrochemical and fluorescent sensing properties for metal ions and anions.