Isoreticular Series of 2-Methylpyridine-Mediated Vinylene-Linked Covalent Organic Frameworks for Efficient Visible-Light-Driven Thiocyanation

Vinylene-linked covalent organic frameworks (COFs) have gained significant attention owing to their outstanding stability, effective π-electron transport, and precise structural tunability, making them promising for visible-light-driven organic transformations. However, the synthesis of vinylene-linked COFs remains challenging, primarily due to the limited availability of monomers with adjustable structures and high reactivity. In this regard, we propose an efficient strategy to expand the repertoire of vinylene-linked COFs by introducing a novel type of tritopic 2-methylpyridine-mediated building block that integrates active methylene sites and tunable functional backbones. By utilizing these tritopic building blocks, a series of isoreticular vinylene-linked two-dimensional (2D) COFs can be readily constructed via a Knoevenagel condensation reaction. The resulting 2D COFs exhibit remarkable crystallinity, stability, and tunable optoelectronic properties, enabling them to function as highly efficient photocatalysts for visible-light-driven thiocyanation reactions. The incorporation of diverse 2-methylpyridine-mediated building blocks would lead to unlocking a plethora of new vinylene-linked COFs, providing unprecedented opportunities to explore the largely unexplored chemistry and properties of this fascinating class of materials.