Synthetic Strategies to Extended Aromatic Covalent Organic Frameworks

• Published in: Chemistry : a European journal 2024-08, Vol.30 (45), p.e202401344-n/a
• Main Authors: Prieto, Tania, Ponte, Clara, Guntermann, Roman, Medina, Dana D., Salonen, Laura M.
• Format: Article
• Language: English
• Subjects: Covalent organic frameworks; Deposition; Optical properties; Post-synthetic modification; Pyrazine; Synthesis; Vinylene-linked COFs; π-extension
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202401344

π‐Conjugated materials are highly attractive owing to their unique optical and electronic properties. Covalent organic frameworks (COFs) offer a great opportunity for precise arrangement of building units in a π‐conjugated crystalline matrix and tuning of the properties through choice of functionalities or post‐synthetic modification. With this review, we aim at summarizing both the most representative as well as emerging strategies for the synthesis of π‐conjugated COFs. We give examples of direct synthesis using large, π‐extended building blocks. COFs featuring fully conjugated linkages such as vinylene, pyrazine, and azole are discussed. Then, post‐synthetic modification methods that result in the extension of the COF π‐system are reviewed. Throughout, mechanistic insights are presented when available. In the context of their utilization as film devices, we conduct a concise survey of the prominent COF layer deposition techniques reported and their aptness for the deposition of fused aromatic systems. This review discusses the most representative as well as emerging strategies for the synthesis of π‐conjugated covalent organic frameworks (COFs), including incorporation of π‐extended building blocks, π‐conjugation through highly conjugated linkages, as well as post‐synthetic modification (PSM) strategies. Various approaches of growing films of such structures are also presented.