Synthesis and high sensitivity Al3+recognition of fluorescent probe molecule based on pincer bis-N-heterocyclic carbene

Two bis-(Nitrogen-Heterocyclic Carbene, NHC) derivatives, 1, 3-bis[1-(quinolin-8-yl)-imidazolium-3-yl)]-benzene bis-hexafluorophosphate ( 2a ), 2, 5-bis[1-(quinolin-8-yl)-imidazolium-3-yl)]-pyridine bis-hexafluorophosphate ( 2b ), were synthesized, and characterized by 1 H NMR and 13 C NMR spectra and X-ray single crystal diffraction. The bis-NHC 2a was demonstrated as an excellent fluorescence chemo-sensor molecule for selectively recognition of Al3 + ion in aqueous-organic media. Its pyridine analogue molecule 2b haven't selectivity recognition character to metal ions with the fluorescence enhancement for most metal ions. A 1:1 binding ratio and strong supramolecular interaction between Al3 + ion and the carbonic hydrogen and quinoline nitrogen were suggested by Job's plot analysis and 1HNMR spectroscopy titrations of Al3 + ion and 2a . The detection limit for Al3 + ion was calculated to be 0.32 mu M. The practical application in tap water samples has been evaluated, which reveals the potential applications of bis-NHC 2a in complicated environments. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Two bis-(Nitrogen-Heterocyclic Carbene, NHC) derivatives, 1, 3-bis[1-(quinolin-8-yl)-imidazolium-3-yl)]-benzene bis-hexafluorophosphate ( 2a ) and 2, 5-bis[1-(quinolin-8-yl)-imidazolium-3-yl)]-pyridine bis-hexafluorophosphate ( 2b ), were synthesized and characterized. The bis-NHC 2a showed excellent fluorescence chemo-sensor properties for selectively recognizing Al3+ ion in aqueous-organic media. The pyridine analogue molecule 2b did not exhibit selective recognition for most metal ions but showed fluorescence enhancement. Job's plot analysis and 1HNMR spectroscopy titrations suggested a 1:1 binding ratio and strong supramolecular interaction between Al3+ ion and the carbonic hydrogen and quinoline nitrogen. The detection limit for Al3+ ion was calculated to be 0.32 mu M. The practical application in tap water samples demonstrated the potential applications of bis-NHC 2a in complicated environments.