Single-layer assembly of pyrene end-capped terthiophene and its sensing performances to nitroaromatic explosives
作者:Taihong Liu、Liping Ding、Keru Zhao、Wenliang Wang、Yu Fang
DOI:10.1039/c1jm14022a
日期:——
A terthiophene (3T) derivative of 5-(1-pyrenyl)-2,2′:5′,2′′-terthiophene (Py-3T) was synthesized and chemically immobilized onto a glass wafer surface via a flexible spacer by employing a single-layer chemistry technique. Unlike the film fabricated in the same way but with 3T as the fluorophore, the film fabricated in the present study possesses unprecedented photochemical stability at ambient conditions. Fluorescence studies revealed that the emission of the film as fabricated is significantly and selectively quenched by the presence of nitroaromatic compounds (NACs), a group of typical explosives, both in the vapor phase and in aqueous solution. Experimental and theoretical studies demonstrated that the quenching may be a result of electron transfer from the electron-rich Py-3T to the electron-deficient NACs. It was found that for vapor phase sensing, the response time and the quenching efficiency of the systems are dominantly determined by the vapor pressures of the NACs tested. The sensing performances of the film to NACs in aqueous phase were also investigated. In this case, however, the specific binding of the film to picric acid (PA), a typical NAC, makes the compound show a superior quenching efficiency than other NACs. Moreover, the response is fast and reaches equilibrium within 90 s. Furthermore, acids, bases, apple juice, perfume, and commonly found organic solventsetc. show little effect upon the sensing in aqueous phase. Both the vapor phase sensing and the aqueous solution sensing are reversible. Furthermore, the film is stable for at least 6 months provided it is properly preserved. The basic contribution of the present work is not only creating a new fluorescent film of superior sensing properties to NACs in the vapor phase, in particular to PA in the aqueous phase, but also providing a new photochemically stable fluorophore, which may combine the advantages of small molecular fluorophores and those of conjugated polymers/oligomers, for developing new fluorescent sensing films.
本研究采用单层化学技术合成了 5-(1-芘基)-2,2′:5′,2′′-三噻吩(Py-3T)的三噻吩(3T)衍生物,并通过柔性间隔物将其化学固定在玻璃晶片表面。与以 3T 为荧光团的相同方法制备的薄膜不同,本研究制备的薄膜在环境条件下具有前所未有的光化学稳定性。荧光研究表明,在气相和水溶液中存在硝基芳香族化合物(NACs)(一类典型的爆炸物)时,所制备薄膜的发射会被明显地选择性淬灭。实验和理论研究表明,淬灭可能是电子从富含电子的 Py-3T 转移到电子缺乏的 NAC 的结果。研究发现,对于气相传感,系统的响应时间和淬灭效率主要取决于所测试的 NAC 的蒸汽压。此外,还研究了薄膜对水相 NAC 的传感性能。在这种情况下,薄膜与典型的 NAC--苦味酸(PA)的特异性结合使得该化合物的淬灭效率优于其他 NAC。此外,酸、碱、苹果汁、香水和常见的有机溶剂等对水相传感的影响都很小。气相传感和水溶液传感都是可逆的。此外,只要保存得当,薄膜至少可以稳定使用 6 个月。本研究的基本贡献不仅在于创造了一种新的荧光膜,其传感性能优于气相中的 NAC,尤其优于水相中的 PA,而且还提供了一种新的光化学稳定荧光团,该荧光团可能结合了小分子荧光团和共轭聚合物/高分子的优点,用于开发新的荧光传感膜。