Dynamic and static fluorescence quenching on the inclusion complex formed by [3-(4-methylphenyl)-4,5-dihydro-1,2-oxazole-4,5-diyl] bis (methylene) diacetate and methyl-beta-cyclodextrin in aqueous media

• Published in: Spectroscopy letters 2020-10, Vol.53 (9), p.692-704
• Main Authors: Ay, Umit, Sarli, Sinem Ezgi, Kara, Yesim S.
• Format: Article
• Language: English
• Subjects: Approximation; Aqueous solutions; Complex formation; Coordination compounds; Cyclodextrins; Differential scanning calorimetry; Diffusion rate; Energy value; Fluorescence lifetime; Fluorescent indicators; Fourier transforms; Gibbs free energy; Heavy metals; inclusion complex; Inclusion complexes; Infrared analysis; Iron; isoxazole derivatives; Mathematical analysis; Methylene; NMR; Nuclear magnetic resonance; Oxazole; Quenching; quenching mechanism; Thermogravimetry; transition metals; Zinc
• ISSN: 0038-7010; 1532-2289
• DOI: 10.1080/00387010.2020.1824194

An inclusion complex was formed between [3-(4-methylphenyl)-4,5-dihydro-1,2-oxazole-4,5-diyl] bis (methylene) diacetate compound, an isoxazole derivative and methyl-beta-cyclodextrin, the smallest unit of the macrocyclic family. With this newly formed fluorescent probe, the induced photophysical properties of heavy metals were investigated. The complex was thermally analyzed by differential scanning calorimetry - thermogravimetry, Fourier transform infrared, proton nuclear magnetic resonance and two dimensional correlated spectroscopy techniques were used for spectral characterization. Complex formation constant, Gibbs free energy and approximate quenching activation energy values were calculated. Lifetime, bimolecular quenching rate constant values and diffusion rate constant calculations were made and the mechanism of the quenching event with heavy metal effect was trying to be clarified. Whether quenching with Zn is dynamic, and whether or not quenching with Fe is static and diffusion controlled were investigated by the sphere of action static quenching, and by the finite sink approximation models. Highlights A new inclusion complex between OXA and Me-β-CD was obtained. The static action and finite approximation models were used for iron. A dynamic and static quenching mechanism was observed for Zn and Fe, respectively. A weak bound encounter complex formation for iron was suggested.