Oxygen is ubiquitous in nature and it plays a key role in several biological processes, such as cellular respiration and food deterioration, to name a few. Currently, reversible and non-destructive oxygen sensing is usually performed with sensors produced by photosensitization of phosphorescent organometallic complexes. In contrast, we propose a novel route of optical oxygen sensing by fluorescence-based quenching of oxygen. We hereby developed for the first time a set of multi-emissive purely organic emitters. These were produced through a one-pot hydrothermal synthesis using p-phenylenediamine (PPD) and urea as starting materials. The origin of the multi-emission has been ascribed to the diversity of chemical structures produced as a result of oxidative oligomerization of PPD. A Bandrowski's base (BB, i.e., trimer of PPD) is reported as the main component at reaction times higher than 8 h. This indication was confirmed by electrospray-ionization quadrupole time-of-flight (ESI-QTOF) and liquid chromatography-mass spectrometry (LC-MS) analysis. Once the emitters are embedded within a high molecular weight poly (vinyl alcohol) matrix, the intensities of all three emission centers exhibit a non-linear quenching provoked by oxygen within the range of 0-8 kPa. The detection limit of the emission centers are 0.89 kPa, 0.67 kPa and 0.75 kPa, respectively. This oxygen-dependent change in fluorescence emission is reversible (up to three tested 0-21% O2 cycles) and reproducible with negligible cross-interference to humidity. The cost-effectiveness, metal-free formulation, cross-referencing between each single emission center and the relevant oxygen range are all appealing features, making these sensors promising for the detection of oxygen, e.g., in food packaged products.

中文翻译：

---

基于多发射荧光猝灭的可逆氧气传感。

氧气在自然界中无处不在，在许多生物过程（例如细胞呼吸作用和食物变质）中起着关键作用。当前，可逆和非破坏性的氧感测通常使用由磷光有机金属配合物的光敏化产生的传感器来进行。相比之下，我们提出了一种通过基于荧光的氧猝灭来进行光学氧传感的新途径。因此，我们首次开发了一组多发射纯有机发射器。这些是通过使用对苯二胺（PPD）和尿素为原料的一锅水热合成法生产的。多次排放的起因是由于PPD氧化低聚而产生的化学结构的多样性。班卓斯基的基地（BB，即 据报道，PPD三聚体是反应时间高于8小时的主要成分。该指示已通过电喷雾电离四极杆飞行时间（ESI-QTOF）和液相色谱-质谱（LC-MS）分析得到证实。一旦将发射器嵌入高分子量聚乙烯醇中，所有三个发射中心的强度就会显示出在0-8 kPa范围内由氧引起的非线性猝灭。发射中心的检测极限分别为0.89 kPa，0.67 kPa和0.75 kPa。这种与氧有关的荧光发射变化是可逆的（最多测试三个0-21％的O2循环），并且对湿度的交叉干扰可忽略不计。成本效益，无金属配方，