A phthalimide-based ESIPT fluorescent probe for sensitive detection of Cu²⁺ in complete aqueous solution

Area of Science:

• Analytical Chemistry
• Chemical Sensing
• Fluorescence Spectroscopy

Background:

• Copper ions (Cu²⁺) are essential but toxic at high concentrations, necessitating accurate detection methods.
• Existing detection methods for Cu²⁺ often lack selectivity or sensitivity.
• Fluorescence-based probes offer advantages in sensitivity and real-time monitoring.

Purpose of the Study:

• To develop a novel fluorescence-enhanced probe for selective and sensitive detection of Cu²⁺.
• To investigate the sensing mechanism based on the excited-state intramolecular proton transfer (ESIPT) process.
• To evaluate the probe's performance in real-world water samples.

Main Methods:

• Synthesis of 2-butyl-1,3-dioxoisoindolin-4-yl picolinate (BDIP) using a phthalimide derivative and picolinate ester.
• Characterization of BDIP's photophysical properties and its response to Cu²⁺ in phosphate buffer saline (PBS).
• Testing the probe's selectivity, anti-interference ability, and detection limit for Cu²⁺.

Main Results:

• BDIP exhibited a significant fluorescence enhancement upon binding with Cu²⁺.
• The probe demonstrated high selectivity and strong anti-interference capabilities.
• A low detection limit of 31 nM for Cu²⁺ was achieved.
• BDIP showed good water solubility and a large Stokes shift.
• Satisfactory results were obtained when applying BDIP for Cu²⁺ detection in real water samples.

Conclusions:

• BDIP is a highly effective and selective fluorescence probe for Cu²⁺ detection.
• The probe's performance in real water samples highlights its practical applicability.
• BDIP offers advantages such as simple synthesis and good photophysical properties for environmental monitoring.