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

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.

Exploring N-BODIPYs as Privileged Scaffolds to Build Off/On Fluorescent Sensors by PET

A new N-boron dipyrromethene (N-BODIPY) substituted with a crown ether moiety has been synthesized by reaction of an F-BODIPY with a crown-ether-substituted bis(sulfonamide). The workability of this N-BODIPY as an off/on sensor for cations by modulation of a photoinduced electron transfer (PET) is explored. The new N-BODIPY demonstrates the possibilities of functionalization of these still unexplored but promising dyes.

A Turn-On Fluorescence-Based Fibre Optic Sensor for the Detection of Mercury

The design, development, and evaluation of an optical fibre sensor for the detection of Hg2+ in aqueous media are discussed in detail in this paper. A novel fluorescent polymeric material for Hg2+ detection, based on a coumarin derivative (acting as the fluorophore) and an azathia crown ether moiety (acting as the mercury ion receptor), has been synthesized. The fluorophore was covalently immobilized onto the fibre surface by polymerisation using the ion imprinting technique and exhibited a significant increase in fluorescence intensity in response to Hg2+ via a photoinduced electron transfer (PET) mechanism. The sensor provided a response over a concentration range of 0–28 µM with an acceptable response rate of around 11 min and a recovery rate of around 30 min in a Tris-EDTA buffer solution. A detection limit of 0.15 µM was obtained with a possibility of improvement by changing the thickness of the polymer layer and using a more sensitive detector. High-quality performance is seen through a high selectivity for Hg2+ over other metal ions, excellent photo-stability and reversibility which was also demonstrated, making this type of sensor potentially well suited for in-situ monitoring of mercury in the environment.

Photophysical properties of a novel styryl-BODIPY with a fused crown ether moiety

The synthesis and characterization of a crown-ether-substituted 3-styrylBODIPY dye with a 4-isopropylphenyl group at the meso-position is reported. The effect that the incorporation of Na[Formula: see text] ions into the crown ether moiety has on the photophysical properties is investigated.