The colorimetric or fluorescent Hg²⁺ sensors received more and more attention because these kinds of sensors possess a lot of advantages such as high sensitivity, not require expensive equipment and easy to operate. The advances in the research of colorimetric or fluorescent sensors for Hg²⁺ are highlighted in this review. We grouped these Hg²⁺ sonsors into three categories according to their recognition mechanisms, reaction based Hg²⁺ sensors, coordination based Hg²⁺ sensors, and nano-materials based Hg²⁺ sensors, respectively. For reaction based sensors, depending on their specific reaction mechanisms, we grouped them into four categories: Hg²⁺ induced Rhodamine spirolactam ring-opening process, Hg²⁺ induced desulfation or deselenization and cyclization process, selective mercuration reaction, and Hg²⁺ catalysed specific reaction. This review summarizes the main design principles, Hg²⁺ recognition abilities and recognition mechanism of these sensors. The developing orientation for futher research is presented. Contents
1 Introduction
2 Design principles of colorimetric or fluorescent Hg²⁺ sensors
3 Reaction based Hg²⁺ sensors
3.1 Hg²⁺ induced Rhodamine spirolactam ring-opening process
3.2 Hg²⁺ induced desulfation or deselenization and cyclization process
3.3 Selective mercuration reaction
3.4 Hg²⁺ catalysed specific reaction
4 Coordination based Hg²⁺ sensors
5 Nano-materials based Hg²⁺ sensors
6 Conclusion and outlook