Three-dimensional conjugated macrocycle with large polyaromatic blocks constructed by post-π-extension

摘要

Generally,the conjugated homo-macrocycles(CHMs)are synthesized by covalently linking the repeating subunits.However,large subunits are often difficult to conjugate together due to severe stereo-hindrance.Meanwhile,large polyaromatic blocks can not only incorporate its appealing electronic and optical properties into CHMs but also distort the CHMs from planar to three-dimensional(3D)molecular structure.Here we synthesized the 3D CHM composed of large polyaromatic units by post-π-extension.Specifically,cyclo-m-phenylenes,as the cyclic precursor,wereπ-extended by C-C coupling and then subjected to dehydrocyclization,affording cyclo-1,3-dibenzo[e,l]pyrenylenes(CMDP).The structures of CMDPs were unambiguously characterized by single crystal X-ray diffraction,showing a congested and strained 3D conformation,which was also confirmed by theoretical calculations.Compared with the monomer,CMDPs showed redshifted absorption and emission,as well as a ten-fold enhancement in photoluminescence quantum yield,which could be attributed to their 3D conformation.