Mercuric ion (Hg^II) is a stable form of mercury pollution with high toxicity and bioaccumulation ability, and its sensitive and visible determination is of great importance. Herein, a simple method to significantly improve the complexation reaction rate between porphyrin and manganous ions (Mn^II) has been implemented by using the synergistic effect of trace nitrogen-doped graphene quantum dots (NGQDs) and Hg(II). A mechanism is proposed in accordance with a substitution reaction in which the deformed porphyrin nucleus by relatively larger Hg(II) ions is favorable for attacking small divalent metal ions carried by NGQDs from the back. Meanwhile, the formation of metalloporphyrin is accompanied by the absorption red-shift and fluorescence quenching of porphyrins; simultaneously, the fluorescence of NGQDs is gradually enhanced because of the inner filter effect between porphyrins and NGQDs. Thus, the ratiometric fluorescence and colorimetric methods for trace Hg^II sensing have been proposed on the basis of the distinct absorption/fluorescence spectral changes, which have potential application in complex environmental and biological conditions.

中文翻译：

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基于氮掺杂石墨烯量子点加速锰卟啉形成的汞离子快速检测

汞离子（Hg ^II）是汞污染的一种稳定形式，具有高毒性和生物蓄积能力，其灵敏可见的测定非常重要。在这里，一种简单的方法可以显着提高卟啉和锰离子（Mn ^II）是利用痕量氮掺杂石墨烯量子点（NGQDs）和Hg（II）的协同效应实现的。根据取代反应提出了一种机制，其中由相对较大的Hg（II）离子形成的变形的卟啉核有利于从背面攻击NGQD携带的小的二价金属离子。同时，金属卟啉的形成伴随着卟啉的吸收红移和荧光猝灭。同时，由于卟啉和NGQD之间的内在过滤作用，NGQDs的荧光逐渐增强。因此，痕量汞^II的比例荧光和比色法 已经基于明显的吸收/荧光光谱变化提出了传感技术，其在复杂的环境和生物学条件下具有潜在的应用。