Synthesis, photophysical and oxygen-sensing properties of a novel Eu3+ complex incorporated in mesoporous MCM-41

A novel Eu3+ complex of Eu(DPIQ)(TTA)3 (DPIQ=10H-dipyrido [f,h] indolo [3,2-b] quinoxaline, TTA=2-thenoyltrifluoroacetonate) was synthesized and encapsulated in the mesoporous MCM-41, hoping to explore an oxygen-sensing system based on the long-lived Eu3+ emitter. The Eu(DPIQ)(TTA)3/MCM-41 composites were characterized by infrared spectra (IR), ultraviolet-visible (UV–vis) absorption spectra, small-angle X-ray diffraction (SAXRD), luminescence intensity quenching upon various oxygen concentrations, and fluorescence decay analysis. The results indicated that the composites exhibited the characteristic emission of the Eu3+ ion and the fluorescence intensity of 5D0–7F2 obviously decreased with increasing oxygen concentrations. The oxygen sensing properties of the composites with different loading levels of Eu(DPIQ)(TTA)3 complex were investigated. A sensitivity of 3.04, a short response time of 7 s, and good linearity were obtained for the composites with a loading level of 20 mg/g. These results are the best reported values for optical oxygen-sensing materials based on Eu3+ complexes so far.