Application of pyrrolo[2,3-b]quinoxaline with an N,N-bis(pyridin-2-ylmethyl)ethylenediamine chain for Zn(II) detection in Candida albicans and fibroblast cells

Publication date: Available online 18 June 2019Source: Journal of Photochemistry and Photobiology A: ChemistryAuthor(s): Majka Duda, Maria Rąpała-Kozik, Katarzyna M. Stadnicka, Bogdan Musielak, Piotr Goszczycki, Łukasz P. Witek, Marcin Zawrotniak, Miriam González-González, Katarzyna OstrowskaAbstractIn the present study, a new 'turn on' fluorescent sensor, (E/Z)-enaminone containing a pyrrolo[2,3-b]quinoxaline group as the fluorophore and a N,N-bis(pyridin-2-ylmethyl)ethylenediamine group as a specific chelator capable of selective detection of Zn2+ is reported. The structure of the ligand was determined by IR, MS, and 1D and 2D NMR, including 1H-15N HMBC correlations. X-ray analysis for (E/Z)-2 confirmed the presence of 90.3% E-diastereoisomer and 9.7% Z-one in the structure of the crystals obtained from acetonitrile. The mechanism of zinc ion recognition is related to the restriction of E/Z-isomerisation of enaminone occurring upon Zn2+ binding that alters the electronic structure of the ligand. Sensing of Zn2+ was confirmed in detail using UV-vis, fluorescent, and 1H NMR titrations, which allowed us to propose the binding mode for complexes formed in the solution during the zinc ion recognition. The ligand functions under physiological conditions and retains its activity in buffer solutions over a wide pH range 2.4–10.6. The developed sensor allowed for intracellular sensing of Zn2+ in human (fibroblast) and fungal (Candida albicans) cells through fluorescence imagi...

Source: Journal of Photochemistry and Photobiology A: Chemistry - June 19, 2019 Category: Chemistry Source Type: research