Previous researches of covalent organic frameworks (COFs) have shown their potential as fluorescent probes, but the regulation of their optical properties and recognition characteristics still remains a challenge, and most of reports required complicated post-decoration to improve the sensing performance. In this context, we propose a novel in-situ strategy to construct uracil-conjugated COFs and modulate their fluorescence properties for sensitive and selective mercury(II) detection. By using 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) and 1,3,6,8-tetrakis(4-aminophenyl)pyrene (TAPPy) as fundamental blocks and 5-aminouraci (5-AU) as the functional monomer, a series of COFs (Py-COFs and Py-U-COFs-1 to Py-U-COFs-5) with tunable fluorescence were solvothermally synthesized through an in-situ Schiff base reaction. The π-conjugated framework serves as a signal reporter, the evenly and densely distributed uracil acts as a mercury(II) receptor, and the regular pores (channels) make the rapid and sensitive detection of the mercury(II) possible. In this research, we manage to regulate the crystalline structure, the fluorescence properties, and the sensing performance of COFs by simply changing the molar ratio of precursors. We expect this research to open up a new strategy for effective and controllable construction of functionalized COFs for environmental analysis.

以往对共价有机框架（COFs）的研究已经显示出它们作为荧光探针的潜力，但其光学性质和识别特性的调控仍然是一个挑战，大多数报道需要复杂的后修饰来提高传感性能。在此背景下，我们提出了一种新的原位策略来构建尿嘧啶共轭 COF 并调节其荧光特性，以实现灵敏和选择性的汞 (II) 检测。通过使用 1,3,6,8-四(4-甲酰苯基)芘 (TFPPy) 和 1,3,6,8-四(4-氨基苯基)芘 (TAPPy) 作为基本嵌段和 5-氨基尿嘧啶 (5-AU) )作为功能单体，通过原位席夫碱反应溶剂热合成了一系列具有可调荧光的COFs（Py-COFs和Py-U-COFs-1至Py-U-COFs-5）。π-共轭骨架作为信号报告器，均匀密集分布的尿嘧啶作为汞(II)受体，规则的孔道(通道)使得汞(II)的快速灵敏检测成为可能。在这项研究中，我们设法通过简单地改变前驱体的摩尔比来调节 COF 的晶体结构、荧光特性和传感性能。我们期望这项研究能够开辟一种有效且可控地构建用于环境分析的功能化 COF 的新策略。以及通过简单地改变前驱体的摩尔比来提高COFs的传感性能。我们期望这项研究能够开辟一种有效且可控地构建用于环境分析的功能化 COF 的新策略。以及通过简单地改变前驱体的摩尔比来提高COFs的传感性能。我们期望这项研究能够开辟一种有效且可控地构建用于环境分析的功能化 COF 的新策略。