Abstract：
Development of metal-free nanozymes has raised concern for their extensive applications in photocatalysis and sensing fields. As novel metal-free nanomaterials, covalent organic frameworks (COFs) have engendered intense interest in the construction of nanozymes due to their structural controllability and molecular functionality. The formation of the molecular arrangement by embedding orderly donor-acceptors (D-A) linked in the framework topology to modulate material properties for highly efficient enzyme mimicking activity is of importance but challenging. Here, a strong D-A type of COF was designed and synthesized by integrating electron donor units (pyrene) and electron acceptor units (phenanthroline), named Py-PD COF. Using experiments and theoretical calculations, the introduction of a phenanthroline ring endowed the Py-PD COF with a narrowed band gap, and efficient charge transfer and separation. Further, the Py-PD COF exhibited a superior light-responsive oxidase-mimicking characteristic under visible light irradiation, which could catalyze the oxidation of 3,3\',5,5-tetramethylbenzidine (TMB) and give the corresponding evolution of color. The nanoenzymatic activity of the Py-PD COF was light-regulated, which offers a fascinating advantage because of its high efficiency and spatial controllability. Based on previously mentioned characteristics, an \"on-off\" sensing platform for the colorimetric analysis of isoniazid (INH) could be constructed with a good linear relationship (2-100 μM) and a low limit of detection (1.26 μM). This research shows that not only is Py-PD COF an environmentally friendly compound for the colorimetric detection of INH, but it is also capable of providing the interesting D-A type COF-based material for designing an excellent nanozyme.
摘要：
无金属纳米酶的发展引起了人们对其在光催化和传感领域的广泛应用的关注。作为新型的无金属纳米材料,共价有机框架（COF）由于其结构可控性和分子功能性而引起了人们对纳米酶构建的强烈兴趣。通过嵌入连接在框架拓扑中的有序供体-受体（D-A）以调节材料特性以实现高效酶模拟活性的分子排列的形成是重要的，但具有挑战性。这里,通过整合电子供体单元（芘）和电子受体单元（菲咯啉），设计并合成了一种强D-A型COF，叫Py-PDCOF.通过实验和理论计算，菲咯啉环的引入使Py-PDCOF的带隙变窄，和高效的电荷转移和分离。Further,Py-PDCOF在可见光照射下表现出优异的光响应氧化酶模拟特性，可以催化3,3'的氧化，5,5-四甲基联苯胺（TMB）并给出相应的颜色演变。Py-PDCOF的纳米酶活性是光调节的，它提供了一个迷人的优势，因为它的高效率和空间可控性。根据前面提到的特征，可以构建用于异烟肼（INH）比色分析的“开-关”传感平台，具有良好的线性关系（2-100μM）和低检测限（1.26μM）。这项研究表明，Py-PDCOF不仅是一种环境友好的化合物，用于比色检测异烟肼，但它也能够提供有趣的D-A型COF基材料，用于设计出色的纳米酶。
