Changes in fluorescent emission due to non-covalent interactions as a general detection procedure for thin-layer...

Area of Science:

• Analytical Chemistry
• Chromatography
• Spectroscopy

Background:

• Thin-layer chromatography (TLC) relies on detection methods to identify separated compounds.
• Fluorescence-based detection is sensitive but requires specific analyte-fluorophore interactions.
• Understanding these interactions is key to developing generalizable TLC detection strategies.

Purpose of the Study:

• To investigate fluorescence emission changes in silica gel plates caused by analyte-fluorophore interactions.
• To propose a model for analyte-induced electrostatic interactions affecting fluorescence.
• To establish criteria for selecting sensitive fluorophore probes for TLC.

Main Methods:

• Studying fluorescence emission changes in silica gel plates.
• Developing a model for analyte-fluorophore induced electrostatic interactions.
• Analyzing the impact of analyte polarizability and microenvironment changes on emission constants (k(r) and k(nr)).

Main Results:

• Analyte presence modifies the fluorophore's microenvironment, altering radiative (k(r)) and non-radiative (k(nr)) emission constants.
• Electrostatic interactions, dependent on analyte polarizability, enhance fluorescence by decreasing k(nr).
• Increased refractive index also contributes to fluorescence enhancement in the silica gel medium.

Conclusions:

• Analyte-induced fluorescence changes are a general property applicable to TLC detection.
• The proposed model explains fluorescence enhancement via electrostatic interactions and microenvironment modification.
• Criteria for sensitive TLC probe selection were discussed, paving the way for improved analytical methods.