Inclusion of Ethyl Acetoacetate Bearing 7‐Hydroxycoumarin Dye by β‐Cyclodextrin and its Cooperative Assembly with Mercury(II) Ions: Spectroscopic and Molecular Modeling Studies. Issue 20 (1st September 2016)

• Record Type: Journal Article
• Authors: Aliaga, Margarita E.; Fierro, Angélica; Uribe, Iván; García‐Río, Luis; Cañete, Álvaro
• Is Part Of: Chemphyschem. Volume 17:Issue 20(2016)
• Page Start: 3300
• Page End: 3308
• Publication Date: 2016-09-01
• Subjects: host-guest systems -- mercury -- molecular modeling -- sensors -- supramolecular chemistry; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201600597
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: The inclusion of the fluorescent organic dye, ethyl 3‐(7‐hydroxy‐2‐oxo‐2 H ‐chromen‐3‐yl)‐3‐oxopropanoate (1 ) by the host β‐cyclodextrin (β‐CD), and its response toward mercuric ions (Hg 2+ ), was studied by UV/Vis, fluorescence, and 1 H NMR spectroscopic analyses, mass spectrometry and molecular modeling studies. 1 H NMR measurements together with molecular modeling studies for dye1 demonstrate that it exhibits two tautomeric forms (keto and enol); however, when the dye is included into the β‐CD cavity, the enol form predominates. Moreover, by using spectroscopic and spectrometry techniques, a 1:1 stoichiometry was determined for the complexes formed between dye1 (enol form) and β‐CD, with a binding constant ( K b1 =1.8×10 4 m −1 ) and for the dye1 (keto form)‐Hg 2+ ( K b2 =2.3×10 3 m −1 ). Interestingly, in the presence of1 –β‐CD complex and mercuric ions, a ternary supramolecular system (Hg–1 –β‐CD complex) was established, with a 1:1:1 stoichiometry and a K b3 value of 4.3×10 3 m −1, with the keto form of the dye being the only one present in this assembly. The three‐component system provides a starting point for the development of novel and directed supramolecular assemblies. Abstract : Getting it together : A cooperative response of mercuric ion binding with a complex of a fluorescent organic dye and β‐cyclodextrin through the formation of a ternary supramolecular complex is demonstrated. The complex maintains the keto form of the dye as the most stable tautomer.