A Highly Selective and Sensitive Fluorescent Turn-Off Probe for Cu²⁺ Based on a Guanidine Derivative

Area of Science:

• Analytical Chemistry
• Materials Science
• Chemical Sensing

Background:

• Copper ions (Cu²⁺) play crucial roles in biological systems but elevated levels can be toxic.
• Development of selective and sensitive probes is essential for monitoring Cu²⁺ in various environments.
• Fluorescent probes offer advantages in sensitivity and real-time detection.

Purpose of the Study:

• To synthesize and characterize a novel naphthalimide-based fluorescent probe for Cu²⁺ detection.
• To evaluate the probe's selectivity, sensitivity, and sensing mechanism for Cu²⁺.
• To establish a spectrofluorometric method for quantifying trace Cu²⁺.

Main Methods:

• Synthesis and structural characterization of the fluorescent probe (L) using IR, NMR, and HRMS.
• Fluorescence spectroscopy to study the interaction between the probe and Cu²⁺.
• Development of a quantitative detection method in an EtOH/H₂O solvent system.

Main Results:

• The synthesized probe (L) demonstrated high selectivity and sensitivity towards Cu²⁺.
• The probe exhibited a
• turn-off
• fluorescence response upon binding with Cu²⁺ at a 1:1 ratio.
• The spectrofluorometric method allowed for the detection of trace Cu²⁺ with an equilibrium binding constant of 1.57 × 10⁴ M⁻¹.

Conclusions:

• The developed fluorescent probe (L) is a promising tool for selective and sensitive detection of Cu²⁺.
• The established spectrofluorometric method provides an efficient way to quantify trace Cu²⁺ levels.
• This research contributes to the advancement of chemical sensing technologies for environmental and biological monitoring.