Use of a new thiacalix[4]arene derivative bearing two 4-chloro-7-nitrobenzofurazan groups as a colorimetric and fluorescent chemosensor for Ag+ and AcO-

The synthesis and spectroscopic studies of a thiacalix[4]arene-based sensor of 1,3-alternate-25,27-bis(2-aminoethoxy)-26,28-bis(2-methoxyethyl)-thiacalix[4]arene linked 4-chloro-7-nitrobenzofurazan (NBD-Cl) are described. The properties of the compound were evaluated and show that it is a colorimetric and fluorescence sensor for Ag+ and AcO-. The addition of Ag+ results in a red shift of the absorption spectrum of the sensor, which is clearly visible to the naked eye, accompanied by a strong quenching of the fluorescence. With the addition of AcO-. the fluorescence was severely quenched, and the absorbance increased significantly, with a new absorption band appearing at shorter wavelength. This demonstrated that the multifunctional sensing compound prepared from a novel thiacalix[4]arene was highly selective for AcO-. (C) 2012 Elsevier B.V. All rights reserved.