Preparation and Characterization of Ternary Europium ComplexDoped Thin SolGel Hybrid Film by Fluorescence Spectroscopy

Ternary europium complex with dibenzoylmethane(DBM)and 1,10phenanthroline(phen)was insitu synthesized in thin SiO2/polyvinyl butyral(PVB)hybrid films by a twostep solgel process and characterized by means of fluorescence spectroscopy.The luminescence spectra,fluorescence lifetimes and photostability were all investigated.The results showed that the hybrid films exhibited the characteristic emission bands of the central rare earth Eu3+.In addition,Eu3+presented longer fluorescence lifetime than in an ethanol solution and the complex had a higher photostability in the hybrid film than in the PVB film containing the corresponding pure complex.

A fluorescent film sensor for high-performance detection of Listeria monocytogenes via vapor sampling

Foodborne Listeria monocytogenes poses serious threats to public health.Fast and sensitive detection of the pathogen at the point of contamination is thus crucial to halt the spread of bacteria-related diseases.Herein,we report for the first time a fluorescent film sensor to detect the biomarker of L.monocytogenes,3-hydroxy-2-butanone.The sensor demonstrated unprecedented sensing performance for the analyte with a detection limit lower than 0.05 mg/m^(3),response time less than 1 s,full reversibility,and excellent selectivity.Further study showed that the sensor can be used to monitor the growth of L.monocytogenes with much-improved sensitivity.The superior performance of the sensor is ascribed to the specific binding,efficient charge transfer emission,and porous adlayer structure of the specially designed sensing fluorophore-based film.Our work paves the way to develop a portable detector to meet the needs for on-site and real-time detection of foodborne pathogens.

Bi-ortho-Carborane Unit-Riveted Perylene Monoimides:Structure-Tuned Optical Switches for Electron Transfer and Robust Thin Film-Based Fluorescence Sensors

Innovative design of sensing fluorophores possessing superior photophysical properties,porosity,and packing-resistance structures is pivotal for high performance film-based fluorescent sensors.Herein,PDCB,a perylene monoimide(PMI)derivative incorporating large spatial phenyl-carborane was synthesized and found to exhibit unexpected photophysical properties.The structurally bent PDCB exhibits not only PMI-like emission but also a red-shifted emission.In sharp contrast,PMI-CBH,a linear PMI derivative,exhibits only PMI-like emission.Furthermore,upon local excitation,PDCB undergoes a photoinduced electron transfer(PET)between PMI and phenylcarborane,resulting in a charge-transfer state.Two other PMI derivatives,PCB and PDCBP,showed a similar phenomenon.The PET rate is in the order of PCB(48 ps^(-1))>PDCB(163 ps^(-1))>PDCBP(815 ps^(-1))in toluene,which decreases with increasing steric hindrance,inferring structure reorganization prior to the PET process.As expected,a fabricated PDCB-based sensor showed excellent performance in acetone sensing.