Dyes and Pigments ( IF 4.5 ) Pub Date : 2018-04-12 , DOI: 10.1016/j.dyepig.2018.04.014 Ashwani Kumar , Pil Seok Chae
In this study, we designed and prepared pyrene-based dipodal probes with a range of molecular flexibility for picric acid (PA) detection. These probes commonly contain a central rigid core, but probe 1 contains relatively short linkers/spacers compared to probes 2 and 3. The dipodal probes produced dominant pyrene excimer fluorescence in an aqueous solution, and aggregation-induced emission enhancement (AIEE) was observed. The fluorescence emission of probe 1 was significantly quenched only by the presence of PA, while probes 2 and 3 were responsive to 4-nitrophenol or 2,4-dinitrophenol as well as PA. Of the three dipodal probes, the highest binding strength was observed for probe 1 with PA, which gave an association constant of Ka = 3.96 × 107 M−1.1H NMR measurements and DFT calculations indicate that, upon addition of PA, these dipodal probes formed individual probe-PA complexes via π–π interactions between the pyrene ring and PA in an aqueous solution. This complex formation enabled energy transfer from electron-rich pyrene to electron-poor PA upon excitation, leading to fluorescence quenching. Probe 1 provided ultra-trace detection of PA in water, with observed and calculated limit of detections (LOD) of 1 nM and 0.13 pM, respectively, one of the lowest values reported. Effective fluorescence quenching was also obtained using probe 1-coated filter paper or TLC plate with PA solution/vapor, suggesting the significant potential of this sensing system in real-time applications. These studies were supported by FE-SEM, TEM, and UV-visible, fluorescence, NMR and DFT calculations.
中文翻译:
构象刚性pyr酰胺基探针的聚集诱导的发射增强行为,用于苦味酸(PA)的超痕量检测
在这项研究中,我们设计并制备了具有pyr柔韧性的pic酸二甲双胍探针,用于苦味酸(PA)检测。这些探针通常包含中央刚性核,但与探针2和3相比,探针1包含相对较短的接头/间隔子。二脚架探针在水溶液中产生主要的pyr准分子荧光,并且观察到聚集诱导的发射增强(AIEE)。仅当存在PA时,探针1的荧光发射才被猝灭,而探针2和3则对4-硝基苯酚或2,4-二硝基苯酚以及PA产生响应。在三种二脚架探针中,探针的结合强度最高1与PA的结合常数为K a = 3.96×10 7 M -1。1 H NMR测量和DFT计算表明,添加PA后,这些双脚探针通过the环和PA在水溶液中的π-π相互作用形成单个的探针-PA络合物。这种复合物的形成使得能量在激发时能从富电子的to转移到贫电子的PA上,从而导致荧光猝灭。探针1提供了水中PA的超痕量检测,观察和计算的检出限(LOD)分别为1 nM和0.13 pM,是报告的最低值之一。使用涂有探针1的滤纸或带有PA溶液/蒸气的TLC板也可以获得有效的荧光猝灭,表明该传感系统在实时应用中具有巨大的潜力。这些研究得到了FE-SEM,TEM和紫外可见光,荧光,NMR和DFT计算的支持。