Crystalline C—C and C═C Bond-Linked Chiral Covalent Organic Frameworks

• DOI: 10.1021/jacs.0c11050
• Publication Date: 2020-12-24T18:12:40Z
• Authors: Chen Yuan; Shiguo Fu; Kuiwei Yang; Bang Hou; Yan Liu; Jianwen Jiang; Yong Cui
• Keywords: Magic angle spinning; Single bond

While crystalline covalent organic frameworks (COFs) linked by C–C bonds are highly desired in synthetic chemistry, it remains a formidable challenge to synthesize. Efforts generate single COFs via de novo synthesis usually afford amorphous structures rather than phases. We demonstrate here that bond-based can be prepared direct reduction of C═C bond-linked crystal-to-crystal transformation. By Knoevenagel polycondensation chiral tetrabenzaldehyde dibinaphthyl-22-crown-6 with 1,4-phenylenediacetonitrile or 4,4′-biphenyldiacetonitrile, two olefin-linked 2D layered tetragonal structure prepared. Reduction olefin linkages the as-prepared CCOFs produces bond frameworks, which retains high crystallinity and porosity as well chemical stability both strong acids bases. The quantitative is confirmed Fourier transform infrared cross-polarization magic angle spinning 13C NMR spectroscopy. Compared pristine structures, reduced display blue-shifted emission enhanced quantum yields fluorescence lifetimes, while parent exhibit higher enantioselectivity analogs when used fluorescent sensors detect amino alcohols supramolecular interactions built-in crown ether moieties. This work provides an attractive strategy for making chemically stable functionalized new otherwise hard produce.