Femtogram Level Detection of Nitrate Ester Explosives via an 8‑Pyrenyl-Substituted Fluorene Dimer Bridged by a 1,6-Hexanyl Unit

• Published in: ACS applied materials & interfaces Vol. 6; no. 11; pp. 8817 - 8823
• Main Authors: Chen, Lei, Gao, Yixun, Wang, Yuerong, He, Chao, Zhu, Defeng, He, Qingguo, Cao, Huimin, Cheng, Jiangong
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.06.2014
• Subjects: femtogram; fluorescent probe; surface sensing; nitroglycerin; fluorescence quenching
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am501543f

Compared with nitroaromatic explosives detection, nitrate esters are far from wide attention possibly because of their shortage of aromatic ring and difficulty in being detected. Three fluorescent chemical probes for trace nitrate ester detection: an intramolecular dimer (P3) of 8-pyrenyl-substituted fluorenes bridged by a 1,6-hexanyl unit as well as its counterparts 2PR-F (P1) and 2PR-Cz (P2) has been synthesized and characterized. Their chemical structures and photophysical and electrochemical properties show that the dimer P3 film has a higher molar extinction coefficient, larger steric hindrance, higher area-to-volume ratio, and matching energy level with nitrate ester explosives, which contributes to higher sensitivity and moderate selectivity for sensing of nitrate ester explosives such as nitroglycerin (NG). The fluorescence of the P3 film is rapidly about 90% quenched upon exposure to a saturated vapor of NG for 50 s and almost 100% quenched for 300 s at room temperature due to photoinduced electron transfer between the probe and analyte. In addition, a very sensitive, rapid, simple, and low-cost surface-sensing method by disposable filter-paper-based test strips is demonstrated. The contact-mode approach exhibits a detection limit as low as 0.5 fg/cm2 for NG. These results reveal that the multiple-pyrenyl-unit-substituted fluorene dimer P3 is suitable for preparing a highly sensitive and efficient thin-film device for detecting nitrate esters.