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

Coronene diimide functionalized with 4-(2-nitrovinyl)phenyl (CDI 2) serves as a precursor for generating a stable radical anion (CDI 2(center dot)(-)) 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(center dot)(-)). The addition of a strong oxidant NOBF4 quenches the radical anion (CDI 2(center dot)(-)). 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(center dot)(-)) 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(center dot)(-)) 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.