Synthesis of novel fluorescence xanthene–aminoquinoline conjugates, determination of dipole moment and selective fluorescence chemosensor for Th4+ ions

• We designed a first based fluorescence chemosensor for Th4+ ions.
• It act as a selective fluorescence chemosensor with detection limit of 87 μM.
• The excited state and ground state dipole moment is estimated from various methods.
• Excited state dipole moment was found in the range of 9.882–1.996 D.

A series of xanthene–aminoquinoline conjugates were synthesized by following a two step procedure. All new compounds were characterized by spectral data and single crystal X-ray crystallography. Xanthene–aminoquinoline conjugates showed strong fluorescence in solution. The effect of solvent polarity, ground and excited state dipole moments of compound 2a were investigated. The ground state dipole moment was estimated to be 0.262 D, while excited state dipole moment was found in the range of 9.882–1.996 D. The effect of common metal ions on fluorescence spectra of compound 2a was also investigated. Compound 2a acts as a fluorescence chemosensor for selective detection of Th4+ ions in solution with linear range of 1 × 10−7 M to 1 × 10−5 M and detection limit of 87 μM.

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