Fluorescent Amorphous Distyrylnaphthalene-Based Polymers: Synthesis, Characterization and Thin-Film Nanomolar Sensing of Nitroaromatics in Water

Abstract

Two new fluorescent segmented conjugated polymers with either 1,4- or 2,6-distyrylnaphthalene chromophores and their model compounds were synthesized and the chemosensing abilities of the polymeric thin films to detect nitroaromatics (NACs) in aqueous media were evaluated. The structural, thermal and optical properties of the polymers were correlated with those displayed by their corresponding model compounds. Changes in the connectivity of naphthylene units caused minor differences in optical properties, morphology and quenching efficiencies. Molecular modeling highlighted the extremely bent character of polymer microstructures that explains their high solubility and amorphous character. Polymeric films are amorphous, strongly fluorescent and showed remarkable quenching efficiencies in the nanomolar range with picric acid (PA) and trinitrotoluene (TNT). Quenching experiments using either different nitroaromatic quenchers, excitation wavelengths, excitation beam path-lengths, or time of exposure of the film to the quenching solution evidenced the dominant role of inner filter effects (IFE) in the polymer response to NACs in the micromolar range. The sensing response towards PA, a quencher that strongly absorbs at the excitation wavelength, has an IFE contribution even at the nanomolar range, while the response towards the non-absorbing TNT depends only on the quenching occurring after diffusion of the analyte into the film.

Photoactive thin films of terphenylene-based amorphous polymers. Synthesis, electrooptical properties, and role of photoquenching and inner filter effects in the chemosensing of nitroaromatics

“…Interestingly, the quenching regime for TNT presents two distinct regions as we observed previously with a structurally different polymer [33]. Thus, the Stern-Volmer plots of P3MF and TNT in Fig.…”

“…We have been interested in developing fluorescent film sensors based on new segmented conjugated polymers for NACs detection in water media. Thus, our group has reported on fluorescent segmented conjugated polymers which present high solubility, amorphous morphologies with no aggregation of chromophores in the condensed phase due to the contorted nature of their main chain (see Scheme 1b), excellent film-forming characteristics and good chemosensing abilities [32,33]. In this study, we synthesized a series of new photoactive amorphous segmented conjugated polymers bearing terphenylene chromophores; and evaluated how chemosensing abilities are dependent on structural modifications and sensing experimental conditions, in order to contribute to establishing structureresponse relationships.…”

Recent advances in film-based fluorescence sensing

“…(3) 分子内电荷转移(ICT), 当识别基团与被分析物结 合后, 会对荧光团的推-拉电子作用产生影响, 从而导 致荧光光谱发生变化 [36,40] . 还有一些机理如荧光内滤 效应(IFE) [41,42] 、激基缔合物的形成 [43] 、配体-金属能 量转移(LMET) [44] 等, 其详细原理本文不再一一赘述. 近年来, 面对高灵敏探测技术的重大需求, 气相传 感器的创制、研发引起了国际社会的重视, 特别是在 美国政府提出的"电子狗鼻计划""真鼻计划""Cell-All" 和"原子到产品"计划等项目的推动下, 相关研究取得 [27] (网络版彩图) .…”

Electrospun fluorescent nanofibrous membranes for trace explosive detection

“…南京邮电大学黄维院士团队 [74] 以烷氧基咔唑芘 (f) 聚合物P的结构式 [43] (网络版彩图) [41] (网络版彩图) 图 7 (a) TMOPP-PS纳米纤维膜的荧光图像; (b) 硝基芳烃 类爆炸物的猝灭效率及其对电纺纳米纤维膜的荧光响应的 常见干扰 [71] (网络版彩图) (c) 不同分析物对PEO/MePyCz电 纺纳米纤维膜的荧光猝灭图 [74] (网络版彩图) 图 9 (a) 空气中PS/PyCz纳米纤维膜的荧光显微镜图; PS/ PyCz纳米纤维膜暴露于DNT蒸气(b)和水蒸气(c) 2 h后的荧 光显微镜图 [75] (网络版彩图) Figure 9 (a) FLM images of nanofibrous film in air; PS/PyCz nanofibrous film exposed to DNT vapor (b) and water vapor (c) for 2 h, respectively [75] (color online). [27,70,73,78] . 一般认为, 硝基芳烃类爆炸物 对共轭聚合物传感器的猝灭机理为: 电子从电子给体 转移到硝基芳烃类爆炸物, 发生荧光猝灭 [43] .…”