Ratiometric room-temperature phosphorescence platform for visual and spectral analysis of naphthalene

Host-guest doping room-temperature phosphorescence (RTP) materials have showed excellent potential for ultra-sensitive detection due to its bright luminescence in presence of trace guests. However, the inherent signal fluctuation of solid-state sensors restricts their widespread applications. Herein we constructed a simple internal standard method to overcome the signal fluctuation problem in RTP spectral analysis. Ultralong organic RTP can be obtained by using 1,4-dichlorobenzene (DCB) as a host and trace gaseous NL as a guest through the host-guest doping strategy. In this study, a dual-emission ratiometric phosphorescent probe pyrene (Py)/pentachloropyridine (PCP)-DCB was constructed by using the Py/PCP system fabricated via melt-casting as the reference afterglow and using the DCB as the stimuli-responsive unit of gaseous NL. This probe can be used for visual identification and content detection of NL in commercial mothballs. The ratio of phosphorescence intensity (I485/I595) was linearly related to the mass of added NL (mNL) within the range of 0.05–1.45 mg in this ratiometric RTP platform, and had a low detection limit of 0.012 mg. Furthermore, the NL content of five commercially available mothballs with different NL content was detected by this Py/PCP-DCB platform, and it had good performance compared to the gas chromatography (GC) analysis results.