Nanoscale LnMOF-functionalized nonwoven fibers protected by a polydimethylsiloxane coating layer as a highly sensitive ratiometric oxygen sensor

Combining the advantages of lanthanide luminescent and porous matrixes, lanthanide metal-organic frameworks (LnMOFs) show great potential in O-2 sensing. In this work, dual-emissive nanoscale LnMOFs, SUMOF-6-Eu, have been chosen as a ratiometric sensor that contains Eu3+-based luminescence as an O-2-sensitive probe and ligand (H(2)pbydc)-based luminescence as an O-2-insensitive reference probe. In order to improve O-2 sensitivity, an in situ crystal-growth method was developed to fabricate nanoscale SUMOF-6-Eu soft films on flexible nonwoven polypropylene (PP) surfaces. After polydimethylsiloxane (PDMS)-coating treatment, the films show high chemical stabilities in moisture, long luminescence lifetimes (1.074 ms) and absolute quantum yields (62%). The coated nanoscale SUMOF-6-Eu films give rise to a high luminescence quenching efficiency of 89.9% at 1 atm O-2 (R-0/R-100 = 7.66) with perfectly linear Stern-Volmer plots (K-SV = 6.73, R-2 = 0.99765), good reversibility, short response/recovery times (10/60 s) and low detection limits (0.45%). This is the first example of soft LnMOF films protected by a water-resistant PDMS layer for ratiometric O-2 sensing.