American Chemical Society
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Exploring the Emissive Properties of New Azacrown Compounds Bearing Aryl, Furyl, or Thienyl Moieties: A Special Case of Chelation Enhancement of Fluorescence upon Interaction with Ca2+, Cu2+, or Ni2+

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journal contribution
posted on 2010-12-06, 00:00 authored by Elisabete Oliveira, Rosa M. F. Baptista, Susana P. G. Costa, M. Manuela M. Raposo, Carlos Lodeiro
Three new compounds bearing furyl, aryl, or thienyl moieties linked to an imidazo-crown ether system (1, 2, and 3) were synthesized and fully characterized by elemental analysis, infrared, UV−vis absorption, and emission spectroscopy, X-ray crystal diffraction, and MALDI-TOF-MS spectrometry. The interaction toward metal ions (Ca2+, Cu2+, Ni2+, and Hg2+) and F has been explored in solution by absorption and fluorescence spectroscopy. Mononuclear and binuclear metal complexes using Cu2+ or Hg2+ as metal centers have been synthesized and characterized. Compounds 2 and 3 show a noticeable enhancement of the fluorescence intensity in the presence of Ca2+ and Cu2+ ions. Moreover compound 3 presents a dual sensory detection way by modification of the fluorimetric and colorimetric properties in the presence of Cu2+ or Hg2+. EPR studies in frozen solution and in microcrystalline state of the dinuclear Cu(II)3 complex revealed the presence of an unique Cu2+ type.