We recently published one last portion from Dr. Yifei Xu's dissertation work on the discrimination of beta-lactam antibiotics in water. This paper was recently published in a special issue of the journal Sensors dedicated to sensors and applications in diagnostics, food and environmental analysis. Yifei, a recent PhD graduate from our group, had previously published a method for discrimination and quantitation of carboxylates in neutral water. Expanding on that work, she was able to develop a method to discriminate carboxylate-containing antibiotics in water media. Widespread abuse of antibiotics (e.g. added to animal feed to improve growth rates, or prescribed in excess) leads to a reduction in their efficacy, and may harm the environment. Yifei's rapid optical chemical sensing method detects very common beta-lactam antibiotics in the penicillin and cephalosporin families in water. This work was also featured in a press release by the Alabama Water Institute. Congratulations Yifei!
Our work on the detection and qualitative discrimination of ion pairs using a coumarin-based receptor and excited-state intramolecular proton transfer (ESIPT) has been published in Inorganic Chemistry. This work describes the results of structural studies (X-ray, NMR) on an ESIPT-capable ligand upon metal binding, including the influence of the metal's counter-anion. We describe the origin of the observed significant Stokes shifts (ca. 225 nm) and lower-energy fluorescence emission (ca. 575 nm) upon metal binding, and the role of the metal's counteranion to induce deprotonation of the ligand. These ligands displayed markedly different behavior toward the considered ion pairs, behaving as dual-channel fluorescent sensors whose response could be harnessed through pattern-based recognition for simultaneous analytical discrimination of metal ions and anions alike.