Thermodynamics of fluorophilicity, lipophilicity, and hydrophilicity of fluorescent molecules

Abstract

Fluorinated derivatives of proflavine, aniline yellow, 1-aminopyrene, and o-aminoazotoluol were synthesized and characterized by ESI-ToF mass spectrometry and 1H/19F NMR spectroscopy, confirming successful fluorination. Their photophysical properties were evaluated using UV-Vis absorption and fluorescence spectroscopy. Fluorinated proflavine and aniline yellow derivatives showed enhanced fluorescence with red-shifted absorption and emission, while proflavine derivatives exhibited the greatest enhancement due to their planar acridine core, extended π-conjugation, and symmetrical incorporation of two perfluoroalkyl chains. Fluorinated 1-aminopyrene and o-aminoazotoluol derivatives displayed chain-length-dependent blue shifts while maintaining improved optical properties. Partition studies demonstrated increased fluorophilicity with longer perfluoroalkyl chains, highlighting the potential of these fluorinated dyes for bioimaging, fluorescence labeling, sensing, and fluorinated-phase applications.