Targeted Synthesis of Isomeric Naphthalene‐Based 2D Kagome Covalent Organic Frameworks

Targeted synthesis of two isomeric naphthalene-based covalent organic frameworks with Kagome topology is realized by rational design of isomeric “two-in-one” monomers with different length of substituents. The specific pore structures of the two isomeric frameworks result in a significant difference in spatial immobilization of C₆₀ guests. Incorporation of C₆₀ into m-Naph-COF increases the photoconductivity of m-Naph-COF, presumably due to the enhanced charge transfer effect.

Abstract

Targeted synthesis of kagome (kgm) topologic 2D covalent organic frameworks remains challenging, presumably due to the severe dependence on building units and synthetic conditions. Herein, two isomeric “two-in-one” monomers with different lengths of substituted arms based on naphthalene core (p-Naph and m-Naph) are elaborately designed and utilized for the defined synthesis of isomeric kgm Naph-COFs. The two isomeric frameworks exhibit splendid crystallinity and showcase the same chemical composition and topologic structure with, however, different pore channels. Interestingly, C₆₀ is able to uniformly be encapsulated into the triangle channels of m-Naph-COF via in situ incorporation method, while not the isomeric p-Naph-COF, likely due to the different pore structures of the two isomeric COFs. The resulting stable C₆₀@m-Naph-COF composite exhibits much higher photoconductivity than the m-Naph-COF owing to charge transfer between the conjugated skeletons and C₆₀ guests.

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