A triply linked propellane-nanoring hybrid serving as a good host

A novel propellane-nanoring hybrid, TPPTI-[9]CMP, was synthesized by triply combining [9]cyclo-meta-phenylene ([9]CMP) with triperyleno[3,3,3]propellane triimides (TPPTI). This structure features two [9]CMP subunits, which necessarily fill the voids of TPPTI and promote assembly of the hybrid to form a porous superstructure held together by attractive dispersion between the [9]CMP subunits of neighboring molecules. In the structure, three large spatial cavities are formed, which allow efficient binding of up to three C₆₀ within a single hybrid. Transient absorption spectroscopy revealed that TPPTI-[9]CMP and C₆₀ interact with each other to form a stable complex and produce long-lived triplet states. Notably, the hybrid can adsorb ethane (C₂H₆) with very excellent selectivity over ethylene (C₂H₄), leading to a highly selective C₂H₆/C₂H₄ separation.