Host-guest chemistry of giant molecular shape amphiphiles based on POSS-PDI conjugates

Giant shape amphiphiles (GSA) are giant molecules made with nano-building blocks that have distinct shapes. The incompatible packing behaviors of the nano-building blocks of GSA could create cavities within certain conformers of the GSA, but the host-guest chemistry of GSA has not been explored yet. In this study, POSS-PDI-POSS (PPP), which is made by connecting two nano-cubes, isobutyl-polyhedral oligomeric silsesquioxanes (POSS), to a conjugated π-conjugated core, perylene diimide (PDI), is demonstrated as a novel acyclic synthetic host. In its bent conformer, PPP shows a cavity next to its PDI core. Via forming host-guest complexes with π-conjugated guests such as pyrene and perylene, PPP is found to transform from the bent-conformer into the extended-conformer, creating the steric features to accommodate guest molecules. Subsequent thermal annealing of the host-guest complexes removes the π-conjugated guests and restores the bent conformation and photophysical properties of PPP, which verifies that PPP, as a novel acyclic host, is capable of dynamic host-guest assembly. Moreover, the results prove that cavities at the molecular level can be created by connecting nano-building blocks with distinct shapes. This finding may inspire developments in the host-guest chemistry of GSA and nanomaterial innovation.

Inclusion crystals of V-shaped host molecules having trialkoxybenzene moieties with a carborane or benzoquinone derivative

Crystallization of an o-carborane or benzoquinone derivative with adamantane-based molecules possessing pyrogallol derivatives resulted in the formation of inclusion crystals through CH⋯O or lone pair⋯π interactions.

Cycloalkanes and cycloalkenes in dispersive force oriented inclusion crystals by a functionalized acyclic host molecule

The complexation of alicyclic compounds with a functionalized acyclic host gave inclusion crystals. Guest molecules were enclathrated within the cavity of the cyclic dimer of host molecules.

Separation of p-xylene from aromatic compounds through specific inclusion by acyclic host molecule

The separation of p-xylene from a mixture of four C₈ alkylaromatics has been realized through highly selective inclusion by an adamantane-based molecule via crystallization. Further, the host molecule specifically discriminated p-xylene from eight C₈ and C₉ aromatic compounds.