Superphanes: Facile and Efficient Preparation, Functionalization and Unique Properties

Superphanes, compounds in which the two benzene rings clamped parallel on top of each other by six bridges, have garnered considerable interest due to their aesthetically pleasing structures and unique chemical physical properties. However, until now progress in the research of superphane chemistry and beyond has been seriously hampered by their poor availability. Herein, we report the facile and scalable synthesis of a collection of superphanes with structural diversity and their unique photophysical properties, as well as their unusual host–guest behavior. Initially, a set of dodecaimino–containing super-phanes 7a–7e are obtained via dynamic self–assembly of a hexakis–amine and a series of readily derived aromatic dialde-hyde in one pot. The resulting superphanes are found capable of being reduced with NaBH4 to their corresponding second-ary–amine versions 3a–3e. Subsequently, superphane 3c bearing 12 amine–NHs was further subject to post–functionalization with various functional groups, e.g., ethyl, allyl, propargyl and but–2–yn–1–yl. Unprecedentedly, the sec-ondary amine–based superphanes 3a–3e were observed to exhibit genuine fluorescence both in solution and in the solid state while the imine–based superphanes 7a–7e were found to highly emissive only in solid state with fluorescent quantum yields of 3.5 ~ 17.1. Finally, fully protonated 3a was exemplified to encapsulate a 2Cl–·H2O cluster both in the solid state and in solution. With the easy and versatile synthesis, modification, as well as unique photophysical and host–guest properties, we believe that this study will break the bottleneck in superphane chemistry and open the door to a novel class of supramo-lecular hosts and advanced functional materials on the basis of superphanes.