Selective and sensitive detection of heavy metal ions is a theme of increasing scientific interest, great technological importance and extensive public concern. To realize this target, design of high-efficient and fluorescent materials as sensor is crucial yet challenging task. In this work, we describes the synthesis and functions of a new hydroxyl and imine groups functionalized covalent organic framework (COFs). The synthesized COFs-DT integrates multi-functionality such as extended π-conjugation framework, tunable functionality, regular pore structure, specific sites to interact with targets as well as robust chemical and thermal stability. COFs-DT shows strong and stable fluorescence when dispersed in isopropanol. The fluorescent property together with the unique bidentate ligand sites enables COFs-DT in the construction of a high-performance fluorescent sensor for detection of Cu²⁺ with high sensitivity and selectivity. Furthermore, we use a series of characterizations to investigate the fluorescence quenching mechanism and found the quenching through a photoinduced electron transfer mechanism with COFs-DT as donor and Cu²⁺ as acceptor. Our strategy not only highlights opportunities for utilizing COFs with integrated multiple unique nature as new type of fluorescent materials, but also expends the encapsulation scope of COFs for ion sensor in environmental field.

选择性和灵敏地检测重金属离子是日益增长的科学兴趣，巨大的技术重要性和广泛的公众关注的主题。为了实现这一目标，设计高效的荧光材料作为传感器是至关重要的，但也是一项艰巨的任务。在这项工作中，我们描述了新的羟基和亚胺基团官能化的共价有机骨架（COFs）的合成和功能。合成的COFs-DT集成了多种功能，例如扩展的π-共轭框架，可调功能，规则的孔结构，与目标相互作用的特定位点以及强大的化学和热稳定性。当分散在异丙醇中时，COFs-DT显示出强而稳定的荧光。²⁺具有高灵敏度和选择性。此外，我们利用一系列表征研究了荧光猝灭机理，并发现了以COFs-DT为供体，Cu ²⁺为受体的光致电子转移机理进行猝灭。我们的策略不仅突出了利用具有多种独特性质的COF作为新型荧光材料的机会，而且扩大了环境领域中离子传感器的COF封装范围。