中国科学院宁波材料技术与工程研究所张涛团队报道了通过亚胺-烯烃转化合成sp2-碳键单晶共价有机框架。相关研究成果于2025年1月6日发表在《自然—化学》。

sp2碳连接的共价有机框架（sp2c-COFs）是一种晶体多孔聚合物，具有由sp2碳链接的重复有机单元，由于其坚固的骨架和可调的半导体性能而引起了越来越多的关注。具有明确结构的单晶sp2c-COFs是研究基本物理性质和器件性能的理想平台。然而，稳健的烯烃键抑制了基于可逆反应的晶体自校正，从而产生多晶或无定形聚合物。

该文中，研究人员报告了一种亚胺到烯烃的转化策略，以形成单晶sp2c-COFs。孤立的单晶显示出尺寸高达约24μm×0.8μm×0.8nm的矩形纳米管状畴，永久孔分布在1.1nm左右。高度共轭的烯烃键赋予晶体增强的电子连接性，决定了其显著的室温无金属铁磁性（8.6×10³emug^-1）。该协议是稳健的，通常适用于合成用于未来自旋电子器件的单晶sp2c-COFs。

附：英文原文

Title: Synthesis of single-crystalline sp2-carbon-linked covalent organic frameworks through imine-to-olefin transformation

Author: Li, Shengxu, Xu, Shunqi, Lin, En, Wang, Tonghai, Yang, Haoyong, Han, Junyi, Zhao, Yuxiang, Xue, Qunji, Samor, Paolo, Zhang, Zhenjie, Zhang, Tao

Issue&Volume: 2025-01-06

Abstract: sp2-carbon-linked covalent organic frameworks (sp2c-COFs) are crystalline porous polymers with repeat organic units linked by sp2 carbons, and have attracted increasing interest due to their robust skeleton and tunable semiconducting properties. Single-crystalline sp2c-COFs with well-defined structures can represent an ideal platform for investigating fundamental physics properties and device performance. However, the robust olefin bonds inhibit the reversible-reaction-based crystal self-correction, thus yielding polycrystalline or amorphous polymers. Here we report an imine-to-olefin transformation strategy to form single-crystal sp2c-COFs. The isolated single crystals display rectangular nanotube-like domains with sizes up to approximately 24μm×0.8μm×0.8μm, and permanent pore distribution around 1.1nm. The highly conjugated olefin linkage endows the crystals with enhanced electronic connectivity which determines a remarkable room-temperature metal-free ferromagnetism (8.6×103emug1). Our protocol is robust and generally applicable for the synthesis of single-crystalline sp2c-COFs for future spin-electron devices.

DOI: 10.1038/s41557-024-01690-y

Source: https://www.nature.com/articles/s41557-024-01690-y