Saturated Linkers in Two-Dimensional Covalent Organic Frameworks Boost Their Luminescence

• Published in: Journal of the American Chemical Society Vol. 145; no. 26; pp. 14417 - 14426
• Main Authors: Yang, Meijia, Hanayama, Hiroki, Fang, Long, Addicoat, Matthew A., Guo, Yunyu, Graf, Robert, Harano, Koji, Kikkawa, Jun, Jin, Enquan, Narita, Akimitsu, Müllen, Klaus
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.07.2023
• Subjects: crystal structure; cyclohexanes; glyoxylic acid; metabolites; photoluminescence; toxicity
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.3c03614

The development of highly luminescent two-dimensional covalent organic frameworks (COFs) for sensing applications remains challenging. To suppress commonly observed photoluminescence quenching of COFs, we propose a strategy involving interrupting the intralayer conjugation and interlayer interactions using cyclohexane as the linker unit. By variation of the building block structures, imine-bonded COFs with various topologies and porosities are obtained. Experimental and theoretical analyses of these COFs disclose high crystallinity and large interlayer distances, demonstrating enhanced emission with record-high photoluminescence quantum yields of up to 57% in the solid state. The resulting cyclohexane-linked COF also exhibits excellent sensing performance for the trace recognition of Fe3+ ions, explosive and toxic picric acid, and phenyl glyoxylic acid as metabolites. These findings inspire a facile and general strategy to develop highly emissive imine-bonded COFs for detecting various molecules.