A new fluorene-based Schiff-base as fluorescent chemosensor for selective detection of Cr3+ and Al3

Mahmood Tajbakhsh; Gholam Babaei Chalmardi; Ahmadreza Bekhradnia; Rahman Hosseinzadeh; Nahid Hasani; Mohammadreza Azizi Amiri

doi:10.1016/j.saa.2017.08.007

A new fluorene-based Schiff-base as fluorescent chemosensor for selective detection of Cr³⁺ and Al³

Spectrochim Acta A Mol Biomol Spectrosc. 2018 Jan 15:189:22-31. doi: 10.1016/j.saa.2017.08.007. Epub 2017 Aug 2.

Authors

Mahmood Tajbakhsh¹, Gholam Babaei Chalmardi², Ahmadreza Bekhradnia³, Rahman Hosseinzadeh², Nahid Hasani², Mohammadreza Azizi Amiri²

Affiliations

¹ Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar 47416-95447, Iran. Electronic address: tajbaksh@umz.ac.ir.
² Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar 47416-95447, Iran.
³ Pharmaceutical Sciences Research Center, Department of Medicinal Chemistry, Mazandaran University of Medical Sciences, Sari, Iran.

PMID: 28787623
DOI: 10.1016/j.saa.2017.08.007

Abstract

2-((9H-fluoren-2-ylimino) methyl)phenol (F3) was synthesized by condensation reaction of 9H-fluoren-2-amine and 2-hydroxybenzaldehyde in EtOH and characterized by its melting point, ¹H-,¹³C NMR and molecular mass. F3 exhibits a high selectivity for detection of Cr³⁺ and Al³⁺ ions as a fluorescent chemosensor and showed a single emission band at 536nm upon excitation at 333nm according to fluorescence emission studies. The addition of Cr³⁺ and Al³⁺ make a significant increase in fluorescent intensity at 536nm in CH₃CN, while other metal ions have almost no influence on the fluorescence. The fluorescence enhancement was attributed to the inhibited CN isomerization and the obstructed excited state intra-molecular proton transfer (ESIPT) of compound F3. Job's plot and DFT calculations data showed that the binding stoichiometries of F3 with Cr³⁺ and Al³⁺ are 2:1. The association constants (K_a) for Cr³⁺ and Al³⁺ were calculated and found to be 8.33×10⁴M^-1 and 5.44×10⁴M^-1, respectively. The detection limits were also calculated for Cr³⁺ and Al³⁺ and found to be 2.5×10^-7mol/L and 3.1×10^-7mol/L, respectively.

Keywords: Chemosensor; Chromium and aluminum ions; DFT; ESIPT; Fluorescence; Schiff-base.