A novel ratiometric fluorescent probe for sensitive and selective detection of Cu²⁺ based on Boranil derivatives

A novel ratiometric fluorescent probe 1, consisting of Boranil derivative as the fluorophore and picolinate as the recognition site for Cu²⁺, was designed and synthesized. 1 was found to display ratiometric response while interacting with Cu²⁺ by undergoing a Cu²⁺-promoted hydrolysis of the picolinate moiety for the release of its precursor, 2. We observed that 1 not only showed quick response time (within 10 min), high sensitivity (detection limit of 0.52 μM), and high selectivity for Cu²⁺ over other metal ions, but also allowed us to detect Cu²⁺ in a convenient way of observing fluorescence color change under a 365 nm UV lamp using naked eyes. Our study introduced the first ratiometric fluorescent probe for Cu²⁺ based on Boranil derivative.