A coronene diimide based radical anion for detection of picomolar H2O2: a biochemical assay for detection of picomolar glucose in aqueous medium

Abstract

Coronene diimide functionalized with 4-(2-nitrovinyl)phenyl (CDI 2) serves as a precursor for generating a stable radical anion (CDI 2˙⁻) using H₂S as a reductant in 40% H₂O–THF solution in the NIR region with stability up to >50 min. The optical, cyclic voltammetry (CV), current–voltage (I–V) and electron paramagnetic resonance (EPR) studies revealed the formation of the radical anion (CDI 2˙⁻). The addition of a strong oxidant NOBF₄ quenches the radical anion (CDI 2˙⁻). The aggregation studies revealed that CDI 2 exists in the aggregated state in 40% H₂O–THF solution, which points to the possibility of stabilization of the radical anion in the aggregates. The radical anion (CDI 2˙⁻) was explored for the detection of 58.27 pM H₂O₂ in aqueous medium with the naked eye colour change from green to light yellow. The biochemical assay involving the radical anion (CDI 2˙⁻) and glucose oxidase (GOx) enzyme can be used for the detection of 16 pM (UV-vis method) and 82.4 pM (fluorescence method) glucose. The naked eye colour change from green to light yellow (daylight) and a colorless non-fluorescent solution to a green fluorescent solution (365 nm) allow the detection of 1 nM glucose.