Cobalt-based coordination polymer imitating nanozymatic Peroxido-Reductase activity for specific and sensitive detection of Fe(II) ions

Abstract

Nanozyme based sensors have evolved as an equable and productive approach for detecting obnoxious metal ions in water samples. A coherent and methodical outlook for nanozymatic sensors is provided in this work. A Co(II) based coordination polymer [Co(L)1.5(ac)3]n named Co-CP, (L = N, N-(benzo-3,8-phenanthroline-2,7-diyl)diisonicotinamide and ac = CH3COO–) has been synthesized in this paper. Co(II) based coordination polymer nanoparticles (Co-CP NPs) constructed by using hand grinding process stimulates the nanozymatic action due to increased surface area and exposure of catalytically active sites. The fabricated Co-CP NPs were characterized using various sophisticated analytical techniques such as SCXRD, HRTEM, FESEM, PXRD etc. The NPs thus formed were about 27 nm in size and pertain porous sites. The Co-CP NPs exhibited peroxido-reductase mimicking activity for TMB(3,3′,5,5′-tetramethylbenzidine) oxidation. The catalytic action of the Co-CP NPs was utilized to detect Fe(II) ion selectively with a detection limit of 0.66 µM. The kinetics for the study were described using Michaelis-Menten curve. The Km and Vmax values for H2O2 and Co-CP NPs were analyzed further to access the catalytic action of Co-CP NPs. XPS and zeta potential analysis were evidenced to elucidate the detection mechanism. The compatibility and practicality of the present method was also assured by actual water samples from different sources that showed good recovery percentage. Therefore, an economical, manageable and equable approach for using CPs as a sensing tool is provided hereby.