Functional Crystals Based on Curved π-Conjugated Sumanene: Design, Assembly, and Emerging Properties

Abstract

  Curved π-conjugated molecules offer unique opportunities for designing functional organic crystals beyond conventional planar systems. Among them, sumanene, one of the representative buckybowl, exhibits a distinctive bowl-shaped geometry that governs its molecular packing and dynamic behavior in the solid state. This article reviews recent advances in the development of functional crystals based on sumanene and its derivatives. Particular emphasis is placed on how substituent engineering enables control over one-dimensional columnar assemblies while preserving the intrinsic packing motif. We highlight fluorinated sumanenes, where dipole moments and intermolecular interactions can be systematically tuned, leading to pronounced dielectric responses originating from in-plane molecular dynamics. Furthermore, solid-solution formation and solvent-dependent crystallization are discussed as effective strategies for modulating dielectric properties. These findings demonstrate that curved π-systems provide a versatile platform for designing adaptive organic crystalline materials with tunable electronic functions, offering new directions for organic dielectric and polar materials.