Abstract Formaldehyde, a volatile organic compound that is ubiquitous in gas pollutants, has an indelible hazard to the health system of humans. Development of simple and convenient ways for the visual detection of formaldehyde in air is still of importance and challenging. In this paper, we report a new type of fluorescence enhancement probe (FAP), which directly exhibited fluorescence enhancement response to formaldehyde with high sensitivity and selectivity. The FAP was synthesized through the substitution reaction between hydrazine and NBD (7-nitrobenzo-2-oxa-1, 3-diazolyl) chloride, that the hydrazine group acted as both fluorescence quencher based on the photo-induced electron transfer (PET) pathway and reaction triggering factor for selectively recognizing formaldehyde. When the FAP was incubated with a formaldehyde-containing circumstance, Schiff base compound was produced by means of the aldimine condensation reaction which inhibited the PET pathway from hydrazine group to NBD, and thus turned on the fluorescence of the FAP significantly. It is worth mentioning that the FAP showed more remarkable response to formaldehyde under acid conditions. Under the optimal experimental conditions, the FAP responded linearly toward formaldehyde in a wide range of 0.015–0.8 mg•L−1, while the fluorescence enhancement was close to 30 times. This FAP was successfully used to detect gaseous formaldehyde in indoor air.

中文翻译：

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基于醛亚胺缩合反应的荧光增强探针检测气态甲醛

摘要 甲醛是一种普遍存在于气体污染物中的挥发性有机化合物，对人类的健康系统具有不可磨灭的危害。开发简单方便的空气中甲醛视觉检测方法仍然具有重要意义和挑战性。在本文中，我们报道了一种新型荧光增强探针（FAP），它以高灵敏度和选择性直接表现出对甲醛的荧光增强响应。FAP是通过肼和NBD（7-硝基苯并-2-氧杂-1，3-二唑基）氯化物之间的取代反应合成的，肼基团作为基于光诱导电子转移（PET）途径的荧光猝灭剂以及选择性识别甲醛的反应触发因子。当 FAP 在含甲醛的环境中孵育时，Schiff碱化合物是通过醛亚胺缩合反应产生的，该反应抑制了PET从肼基团到NBD的途径，从而显着开启了FAP的荧光。值得一提的是，FAP 在酸性条件下对甲醛表现出更显着的响应。在最佳实验条件下，FAP在0.015-0.8 mg•L-1的大范围内对甲醛呈线性响应，而荧光增强接近30倍。该 FAP 已成功用于检测室内空气中的气态甲醛。值得一提的是，FAP 在酸性条件下对甲醛表现出更显着的响应。在最佳实验条件下，FAP在0.015-0.8 mg•L-1的大范围内对甲醛呈线性响应，而荧光增强接近30倍。该 FAP 已成功用于检测室内空气中的气态甲醛。值得一提的是，FAP 在酸性条件下对甲醛表现出更显着的响应。在最佳实验条件下，FAP在0.015-0.8 mg•L-1的大范围内对甲醛呈线性响应，而荧光增强接近30倍。该 FAP 已成功用于检测室内空气中的气态甲醛。