One Molecular Probe with Opposite Enantioselective Fluorescence Enhancement at Two Distinct Emissions

Area of Science:

• Analytical Chemistry
• Organic Chemistry
• Biochemistry

Background:

• Chiral molecules exist as non-superimposable mirror images (enantiomers).
• Distinguishing and quantifying enantiomers is crucial in pharmaceuticals and biochemistry.
• Fluorescent probes offer sensitive detection methods for chemical species.

Purpose of the Study:

• To develop a chiral fluorescent probe for enantioselective detection of histidine.
• To enable simultaneous determination of histidine concentration and enantiomeric composition.
• To elucidate the reaction mechanisms underlying the enantioselective fluorescent responses.

Main Methods:

• Synthesis of a 1,1'-binaphthyl-based chiral dialdehyde fluorescent probe.
• Complexation of the probe with Zn²⁺ under slightly acidic conditions.
• Spectroscopic analysis (fluorescence emission) of probe-histidine interactions.

Main Results:

• The probe exhibits distinct fluorescence emission wavelengths (517 nm and 575 nm) in response to different histidine enantiomers.
• One enantiomer enhances fluorescence at 517 nm, while the opposite enhances it at 575 nm.
• Mechanistic studies revealed two distinct reaction pathways leading to dimeric and polymeric products with different emissions.

Conclusions:

• The developed probe provides a single-solution method for simultaneous quantification and enantiomeric excess determination of histidine.
• The probe's dual-emission capability stems from enantiomer-specific reaction pathways.
• This approach offers a novel strategy for chiral analysis using fluorescent probes.