Recently, researchers from the Chinese Academy of Sciences Shanghai Institute of Microsystems and Information Technology have made progress in the research of thin film fluorescent sensors. This study provides an effective strategy for preparing excellent thin film fluorescence sensors, and experimentally verifies and theoretically explains the synergistic process of fluorescence sensing and gas adsorption. The related achievements are titled Fluorophor embedded MOFs steel gas ultra recognition and published in Advanced Functional Materials.
In recent years, thin-film fluorescence sensors have played an important role in the field of gas sensing. Due to their high sensitivity, responsiveness, and selectivity, they are currently one of the most promising trace substance detection technologies. However, most fluorescence sensitive materials exhibit aggregation fluorescence quenching (ACQ) effect and photobleaching phenomenon, making it rare to find fluorescence sensing materials that meet practical application requirements. This limits the application of fluorescent sensitive materials in gas detection, and there is an urgent need to develop new high-performance sensitive materials for gas sensing. In response to the problems of poor solid-state fluorescence quantum efficiency and poor photostability faced by thin film organic fluorescence probe materials, researchers have loaded organic fluorescence guests into metal organic frameworks (MOFs) and developed a novel host guest type thin film fluorescence gas sensor with high sensitivity, selectivity, and stability for gas analytes. This provides a flexible method for constructing thin film fluorescence sensors that meet different needs.
This work uses ACQ molecule Me4BOPHY-1 as the encapsulated organic guest and embeds it into the metal organic framework ZIF-8 using a simple solid-phase synthesis method. The fluorescence emission characteristics are adjusted by adjusting the loading ratio. MOFs (ZIF-8) provide various nanocavities for guest molecules, thereby reducing the self aggregation of fluorescent molecules and effectively overcoming the ACQ effect of Me4BOPHY-1. After loading different proportions of guests, the solid-state fluorescence quantum efficiency of the molecule increased from the highest of 0.76% to 19.72%. Furthermore, the study achieved gas phase recognition of diethyl chlorophosphate, a analogue of the neurotoxic agent sarin.
Research on MEMS cantilever beam adsorption shows that the host guest embedded MOF sensor endows the probe with excellent gas sensing ability for pre enrichment of the measured gas, with a response time of up to 3 seconds and a detection limit as low as 1.13 ppb. The cage effect of MOFs improves the selectivity for analytes, Me4BOPHY-1@ZIF-8 The response to the interfering gas HCl has significantly weakened, which has been unavoidable in previous literature reports. In addition, the "cage effect" of the organic metal framework structure also ensures good photostability and thermal stability of the sensor. The thermal decomposition temperature of organic fluorescent molecules increased from 200 ℃ to 527 ℃, and the initial fluorescence intensity was still maintained under continuous 4800 s of laser irradiation in the excitation light band.
