A Fluorescent Sensor for Cu²⁺ Ion with High Selectivity and Sensitivity Based on ICT and PET

Area of Science:

• * Chemical Sensing
• * Materials Science
• * Analytical Chemistry

Background:

• * Development of selective fluorescent sensors for metal ion detection is crucial.
• * 1,8-naphthalic anhydride derivatives offer potential for chemosensor design.
• * Copper ions (Cu²⁺) play vital roles in biological systems and environmental monitoring.

Purpose of the Study:

• * To synthesize and characterize a novel fluorescent sensor (L) based on 1,8-naphthalic anhydride.
• * To investigate the selective detection of copper ions (Cu²⁺) in acetonitrile.
• * To elucidate the sensing mechanism and determine the sensor's performance.

Main Methods:

• * Synthesis of a 1,8-naphthalic anhydride-based fluorescent sensor (L).
• * Spectroscopic analysis including fluorescence and UV-vis absorption.
• * Electrochemical and computational studies (Density Functional Theory).
• * Titration methods (Job's plot, fluorescence, 1H NMR) for complexation studies.

Main Results:

• * The sensor (L) selectively detected Cu²⁺ in acetonitrile via fluorescence quenching (turn-off).
• * Spectroscopic changes indicated intramolecular charge transfer (ICT) and photoinduced electron transfer (PET) mechanisms.
• * A 1:1 complexation ratio between L and Cu²⁺ was confirmed.
• * A low detection limit of 9.1 × 10^-8 mol·L^-1 for Cu²⁺ was achieved.

Conclusions:

• * The developed sensor demonstrates high selectivity and sensitivity for Cu²⁺ detection.
• * The sensing mechanism involves coordination-induced ICT and PET processes.
• * The sensor shows promise for practical applications in detecting copper ions.