AIEE active fluorophores for the sensitive detection of iron ions: An advanced approach towards optical and theoretical investigation

Iron is an essential microelement and the most abundant transition metal in humans that catalyzes different crucial metabolisms. It also has broader industrial applications as a precursor for the manufacturing of different domestic products. However, its excess in the biological and environmental matrixes induce adverse health ef-fects. Considering the significant role of the iron in numerous biological processes and environmental safety threats, immediate sensing of iron in a complex system is inevitably pivotal. In the pursuit of these concerns, two efficient solvatochromic and AIEE active TPA based sensors TPA 1 and TPA 2 were critically designed and synthesized for the development of efficient sensing materials. The proposed sensors TPA 1 and TPA 2 were exploited as an easy-to-apply platform for the sensitive and selective optical tracing of the iron (Fe (II)) in aqueous media (H2O/THF; 4:1, v/v) through sensor-metal chelation induced fluorescence quenching (CHEQ) mechanism with LOD down to 15 and 19 nM, respectively. The optical investigations were validated through 1H NMR titration, extensive theoretical studies, and Jobs plot experiment. Further, AIEEgens were advantageously utilized to establish the ready-to-use and hand-held fluorescent kits for the solid state Fe (II) trailing. The spike -recovery experiments were executed to quantify Fe (II) in wheat flour and real water samples. Besides, the practical applicability potential of the designed sensors was explored by executing MTT assay and monitoring of the Fe (II) in blood serum samples. Additionally, a logic circuit was rationally fabricated for the digital on-field sensing of Fe (II). To the best of our knowledge, these are the first TPA based compounds with fabulous structural simplicity, and startling practical applicability as sensitive iron sensors.

Automated summary

Iron is an essential microelement and a crucial catalyst in humans, but its excess poses health risks. In this study, efficient solvatochromic and AIEE active TPA based sensors TPA 1 and TPA 2 were designed and synthesized for sensitive detection of iron. The sensors showed selective optical tracing of iron (Fe (II)) in aqueous media through fluorescence quenching mechanism with low detection limits. They were also applied in solid state Fe (II) trailing and demonstrated practical applicability in quantifying Fe (II) in wheat flour, water samples, and blood serum.