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Elsevier, Journal of Photochemistry and Photobiology A: Chemistry, (259), p. 33-40

DOI: 10.1016/j.jphotochem.2013.03.001

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Naphthyl-imidazo-anthraquinones as novel colorimetric and fluorimetric chemosensors for ion sensing

Journal article published in 2013 by Rosa M. F. Batista, Susana P. G. Costa ORCID, M. Manuela M. Raposo ORCID
This paper is available in a repository.
This paper is available in a repository.

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Abstract

Novel colorimetric and fluorimetric chemosensors for F−, CN− and OH− containing anthraquinone and imidazole as signalling/binding sites have been synthesised and characterised. Upon addition of F−, CN− and OH− to acetonitrile solutions of compounds 1 and 2, a marked colour change from yellow to pink was observed and the fluorescence emission of 1 was switched “on”, whereas for 2 there was a fluorescence quenching. Considering recognition in organic aqueous mixture, it was found that selectivity for CN− was achieved for both receptors, with an easily detectable colour change from yellow to orange. Moreover, sensors 1 and 2 showed good sensitivity with μM-level detection limit for cyanide in acetonitrile as well as in acetonitrile/water (9:1). Additionally, compounds 1 and 2 in their deprotonated form, after fluoride addition, were studied as metal ion chemosensors and displayed a drastic change from pink to yellow after metal ion complexation giving a yellow–pink–yellow, reversible colorimetric reaction and a “on-off-on” fluorescence in acetonitrile. The binding stoichiometry between the receptors and the anions and cations was found to be 1:1 and 2:1, respectively. The binding process was also followed by 1H NMR titrations which corroborated the previous findings.