A novel multimode sensor showing cation-dependent fluorescence colour.

Area of Science:

• Analytical Chemistry
• Materials Science
• Photophysics

Background:

• Development of selective and sensitive fluorescent sensors for metal ion detection is crucial.
• Existing sensors often lack the ability for simultaneous identification and quantification.
• Novel sensor design is needed to address these limitations.

Purpose of the Study:

• To synthesize and characterize a novel fluorescent sensor, 4-[2-(9-anthryl)ethynyl]-1,10-phenanthroline (1).
• To investigate the sensor's photophysical properties and its response to divalent metal cations (M2+).
• To demonstrate the sensor's capability for simultaneous identification and quantification of M2+.

Main Methods:

• Synthesis of the fluorescent sensor 1.
• Spectroscopic analysis (UV-Vis absorption, fluorescence emission).
• Photophysical measurements (quantum yield, lifetime) in acetonitrile (CH3CN).
• Titration experiments with various divalent metal cations (Ba2+, Ca2+, Mg2+, Zn2+).

Main Results:

• Sensor 1 exhibits intense fluorescence (λf = 470 nm, Φf = 0.90, τf = 4.2 ns) in CH3CN.
• Upon binding M2+, sensor 1 shows cation-dependent fluorescence shifts (λf = 514-584 nm) and altered photophysical properties (Φf = 0.90-0.19, τf = 2.1-6.9 ns).
• A linear correlation was observed between the fluorescence maximum energy of the [1-M2+] complex and the pKa value of M2+.

Conclusions:

• Sensor 1 enables simultaneous identification of M2+ based on fluorescence wavelength (λf).
• Quantification of M2+ is achievable using fluorescence intensity (Φf).
• The sensor demonstrates potential for selective and sensitive detection of divalent metal cations.