A Europium-Based Optical Sensor for the Detection of Carbon Dioxide and Its Application for a Fermentation Reaction

A new europium-based complex, K[Eu(hfa)4] with hfa = hexafluoroacetylacetonate is synthesized and its structure confirmed via X-ray crystallography. The unravels an anionic octa-coordinate K[Eu(hfa)4], as opposed to the neutral hexacoordinate complex Eu(hfa)3 routinely/ubiquitously presumed be case in literature. displayed pH-dependent, “on–off” emission changes solution exhibited a pKa of 6.13 ± 0.06 ethylene glycol. In solution, sensor drastic variation intensity corresponding concentration CO2 gas purged. Based on multiple purge cycles N2 CO2, can correlated solution. sensor’s ability quantify presence based variations 5D0 → 7F2 line Eu(III) at 618 nm. exhibits linear response concentrations range 0–25% (0–8.50 mM or 0–189.95 mmHg). calibration data, limit detection (LOD) determined 0.57% (0.19 4.33 mmHg) I100/I0 ratio 80.29 3.79. percent change from purging 100% 7911.16%. Over course seven different there essentially no deviation indicating stability reversibility. addition analytical characterization sensor, mechanism sensing investigated using cyclic voltammetry, IR, Raman spectroscopy. These data indicate reduction europium(III) europium(II) alkaline medium suggest ligand chemistry (association/dissociation protonation) due purging. potential use for real-life applications herein evaluated well-known fermentation reaction. generated during yeast’s anaerobic respiration sucrose media quantified calibrated, commercial probe; both exhibit similar values, validating curve viability bona fide sensor. collected, highly stable, brightly red-emissive differentiate hereby developed characterized benefits various applications.