Selective naked-eye detection of dopamine using an imino-boron molecular capsule

Abstract

Biogenic amines are responsible for transmitting electrical impulses in biological systems and hold immense physiological significance. To detect these amines under physiological conditions, optical sensing methods are favoured due to their simplicity, affordability, and rapid response. Probes based on macrocycles or molecular capsules have proven superior for chemosensing applications due to their unconventional structures and intriguing properties. Here we report the synthesis of a BF₂-containing molecular capsule with high luminescence and long lifetimes in solution and in the solid state. The cylindrical cavity in the capsule encompassing polarised B^δ+–F^δ− bonds facilitates the formation of multiple hydrogen bonds with dopamine, and the complexation is signalled through visual changes in colour and fluorescence. The mechanism of interaction was studied using fluorescence and NMR spectroscopy and further supported by molecular dynamics simulations, which revealed that multiple non-covalent interactions between the molecular capsule and dopamine are responsible for stabilizing the inclusion complex. Finally, we demonstrate the use of the molecular capsule as a simple probe by preparing a test strip using a polymer for the sensing of dopamine under various conditions.