Premium
Inclusion of Ethyl Acetoacetate Bearing 7‐Hydroxycoumarin Dye by β‐Cyclodextrin and its Cooperative Assembly with Mercury(II) Ions: Spectroscopic and Molecular Modeling Studies
Author(s) -
Aliaga Margarita E.,
Fierro Angélica,
Uribe Iván,
GarcíaRío Luis,
Cañete Álvaro
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201600597
Subject(s) - cyclodextrin , mercury (programming language) , chemistry , ethyl acetoacetate , ion , inclusion (mineral) , inclusion compound , molecular model , organic chemistry , catalysis , mineralogy , computer science , programming language
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 dye 1 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 dye 1 (enol form) and β‐CD, with a binding constant ( K b1 =1.8×10 4 m −1 ) and for the dye 1 (keto form)‐Hg 2+ ( K b2 =2.3×10 3 m −1 ). Interestingly, in the presence of 1 –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.