Effects of isomorphous substitution of a coordination polymer on the properties and its application in electrochemical sensing

This work concerns the isomorphous substitution of coordination polymers (CPs) and its effect on the optical and electrochemical properties. The application of CPs in electrochemical sensing was studied as well. Isomorphous coordination polymers, [CoxZn1−xtyr]n (tyr=L-tyrosine), where x (0–1) was controlled by the Co/Zn ratios of raw materials, were successfully synthesized via a hydrothermal method, as proved by XRD and EDS results. Their UV–vis DRS and fluorescence spectra change gradually along with the composition. Cyclic voltammograms of modified electrodes, [CoxZn1−xtyr]n/GCE, show that as more and more Zn replaced Co, the current signal decreases greatly and the potential shifts negatively. Much attention was paid to [Cotyr]n due to its highest sensitivity. Refreshable modified carbon paste electrode, [Cotyr]n-CPE, was used to determine nitrite, and showed pretty good performance as evidenced by chronoamperometry. The response was made very fast within mere 5 s. The linear detection range was from 5.00×10−5 to 3.45×10−3 M, with sensitivity of 263.4 mA mol−1 L cm−2. The detection limit was found to be 2.00×10−5 M. The sensor also showed good antiinterference and reproducibility. - Graphical abstract: Evolution of the optical and electrochemical properties of isomorphic coordination polymers [CoxZn1−xtyr]n along with the changing of x was studied. The CP also showed perfect performance in the electrochemical determination of nitrite. - Highlights: • Isomorphous substitution of coordination polymers (CPs). • Substitution-caused evolution of optical and electrochemical properties of CPs. • Application of CPs in electrochemical sensing, an incipient area. • Perfect performance of CPs in electrochemical determination of nitrite