As an analog of graphene, carbon nitrides have drawn increasing attention, ranging from artificial photosynthesis to synthetic organic chemistry. Notably, the most studied polymeric, C₃N₄, and other stoichiometric ones, such as C₃N₅, C₄N₃, and C₃N, are commonly employed repetitive units of six-membered rings. Building blocks of five-membered rings (FMRs) are also fascinating and prevalent from a fundamental point of view, but FMR-based carbon nitrides are scarcely reported. Here, we propose a stable FMR-based C₃N₂ and the kinetic-oriented synthesis method via a pre-stabilization strategy using abundant-available zeolitic imidazolate framework as a precursor. The FMR topological structure and the associated dangling bonds were disclosed in C₃N₂, leading to an interesting p-π conjugation and splitting molecular orbitals, which remarkably narrowed the optical bandgap unusually down to 0.81 eV. The as-obtained C₃N₂ was further successfully applied to real-time, dynamic, and quantitative photoelectrochemical biosensing for practical non-transparent biosamples under near-infrared light irradiation.

作为石墨烯的类似物，氮化碳引起了越来越多的关注，从人工光合作用到合成有机化学。值得注意的是，研究最多的聚合物 C ₃ N ₄和其他化学计量的聚合物，如 C ₃ N ₅、C ₄ N ₃和 C ₃ N，是常用的六元环重复单元。从基本的角度来看，五元环 (FMR) 的构建块也很吸引人和普遍，但几乎没有报道基于 FMR 的碳氮化物。在这里，我们提出了一个稳定的基于 FMR 的 C ₃ N ₂以及通过使用丰富的沸石咪唑酯骨架作为前体的预稳定策略的动力学导向合成方法。FMR 拓扑结构和相关的悬空键在 C ₃ N ₂中公开，导致有趣的 p-π 共轭和分子轨道分裂，这显着地将光学带隙缩小到 0.81 eV。所获得的C ₃ N ₂进一步成功地应用于近红外光照射下实际不透明生物样品的实时、动态和定量光电化学生物传感。