Guest Binding via N-H···pi Bonding and Kinetic Entrapment by an Inorganic Macrocycle

Modern supramolecular chemistry is overwhelmingly based on non-covalent interactions involving organic architectures. However, the question of what happens when you depart from this area to the supramolecular chemistry of structures based on non-carbon frameworks remains largely unanswered, and is an area that potentially provides new directions in molecular activation, host–guest chemistry, and biomimetic chemistry. In this work, we explore the unusual host–guest chemistry of the pentameric macrocycle [{P(mu-NtBu}2NH]5 with a range of anionic and neutral guests. The polar coordination site of this host promotes new modes of guest encapsulation via hydrogen bonding with the p systems of the unsaturated C/Cand C/N bonds of acetylenes and nitriles as well as with the PCO- anion. Halide guests can be kinetically locked within the structure by oxidation of the phosphorus periphery by oxidation to PV. Our study underscores the future promise of p-block macrocyclic chemistry.