Synthesis of Ni-MOF electrochemical-fluorescence dual sensor and differentiated detection of phenylenediamine isomers

Environmental pollution is a hot topic of concern for countries around the world. Therefore, {[Ni(NDC)(phen)(H 2 O)]• n ( Ni-1 , NDC = 2,6-naphthalenedicarboxylic acid, phen = o-phenanthroline), a 1D Ni-MOF, was synthesized using the solvothermal method as an electrochemical-fluorescence dual sensor for detecting phenylenediamine isomers. By the difference in the position of the reduction peaks, it is possible to distinguish between isomers while detecting them. The electrochemical behavior of the Ni-1 /GCE sensing phenylenediamine isomers was analyzed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The LODs of o-PDA, m-PDA and p-PDA were 2.567 μM, 1.984 μM and 0.4003 μM in the detection range of 5–50 μM, respectively. Ni-1 was highly stable in aqueous solution (H 2 O), so it was dissolved in H 2 O to fabricate the Ni-1 /H 2 O fluorescence sensor. Ni-1 /H 2 O exhibited Stern-Volmer quenching constants of 6.080 × 10 4  M −1 , 2.086 × 10 3  M −1 , and 6.417 × 10 3  M −1 for o-PDA, m-PDA, and p-PDA, respectively. In addition, this dual sensor still shown excellent immunity to interference under the organic interferents. This work provides an efficient, convenient, and sensitive dual sensing method for the detection and differentiation of phenylenediamine isomers, which is of great significance for the detection of aromatic amines in the fields of wastewater discharge, environmental protection, and food safety.