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Imidazoanthraquinone Derivatives for the Chromofluorogenic Sensing of Basic Anions and Trivalent Metal Cations

Marín-Hernández, Cristina, Santos-Figueroa, Luis E., Moragues, María E., Raposo, M. Manuela M., Batista, Rosa M. F., Costa, Susana P. G., Pardo, Teresa, Martínez-Máñez, Ramón, Sancenón, Félix
Journal of organic chemistry 2014 v.79 no.22 pp. 10752-10761
absorption, acetonitrile, aluminum, anions, barium, bromides, cadmium, calcium, cations, chemical derivatives, chlorides, chromium, cobalt, copper, fluorides, iron, lead, lithium, magnesium, moieties, nickel, organic chemistry, potassium, zinc
Four imidazoanthraquinone derivatives (2a–d) were synthesized and characterized and their coordination behavior against selected anions and cations tested. Acetonitrile solutions of probes showed charge-transfer absorptions in the 407–465 nm range. The four probes emitted in the 533–571 nm interval. The recognition ability of 2a–d was evaluated in the presence of F–, Cl–, Br–, I–, OCN–, BzO–, ClO₄–, AcO–, HSO₄–, H₂PO₄–, and CN–. Only F–, AcO–, and H₂PO₄– induced a new red-shifted absorption band that was attributed to a deprotonation process involving the amine moiety of the imidazole ring. Moreover, upon increasing quantities of F–, AcO–, and H₂PO₄–, moderate quenching was induced in the emission of 2a–d together with the appearance of a new red-shifted band. The UV–visible and emission behavior of the four probes in the presence of Cu²⁺, Co²⁺, Mg²⁺, Fe³⁺, Ba²⁺, Fe²⁺, Ni²⁺, Ca²⁺, Zn²⁺, Pb²⁺, Cd²⁺, Cr³⁺, Al³⁺, K⁺, and Li⁺ was also assessed. Only addition of Fe³⁺, Cr³⁺, and Al³⁺ caused a new blue-shifted band in 2a–d that was ascribed to a preferential coordination with the acceptor part of the probes. Moreover, an important quenching of the emission was observed which was ascribed to the interaction between these trivalent cations and 2a–d.