Crown Ether Benzoxazolyl-Alanines as Fluorimetric Chemosensors for the Detection of Palladium in Aqueous Environment

Abstract

Palladium has wide application in different contexts and, as a consequence, high levels of palladium in the environment have been reported, representing a risk to human health. Considering the interest to develop more selective and sensitive chemosensors for this analyte, two novel benzoxazolyl-alanine derivatives bearing a crown ether moiety were studied as potential fluorimetric chemosensors for palladium detection. Preliminary chemosensory studies for these unnatural amino acids in the presence of selected metal cations were performed in acetonitrile solution and in aqueous mixtures of sodium dodecyl sulfate (SDS, 20 mM, pH 7.5) solution with acetonitrile, 90:10 v/v. In acetonitrile solution, these probes had a fluorescence response for different cations but, most importantly, in SDS aqueous solution both compounds displayed a selective fluorescence response in the presence of palladium.

Synthesis and Evaluation of an Azo Dye for the Chromogenic Detection of Metal Cations

“…Following this group's interest in the synthesis and evaluation of optical chemosensors for various ions [15][16][17][18], we report herein the synthesis of Dabcyl, as well as its evaluation as a potential colorimetric chemosensor for metal cations through chemosensing studies in the presence of several cations in acetonitrile solutions.…”

Novel Crown Ether Amino Acids as Fluorescent Reporters for Metal Ions

“…The photophysical properties of crown ether benzoxazolyl-alanines 3a-e were evaluated by UV-vis absorption and fluorescence spectroscopy of degassed 1.0 × 10 −5 M solutions in UV-grade acetonitrile [32]. The UV-Vis absorption and fluorescence data (maximum wavelength of absorption, λ abs ; molar absorptivity, ε; maximum fluorescence wavelength, λ em ; relative fluorescence quantum yield, Φ F ; and Stokes' shift, ∆λ) are presented in Table 1.…”

A Sulfo-Cyanine Dye as a Colorimetric Chemosensor for Metal Cation Recognition

“…Bearing these facts in mind, and considering the research group's experience on the design, synthesis, and characterization of heterocyclic optical chemosensors [8,[15][16][17], we report herein the evaluation of a sulfonated pentamethine cyanine (sulfo-Cy5) dye as a potential colorimetric chemosensor for metal cation recognition. Therefore, interaction studies of this dye in the presence of several cations were performed through a preliminary chemosensory study, followed by spectrophotometric titrations.…”