The rationalization of non-covalent binding trends is both of fundamental interest and provides new design concepts for biomimetic molecular systems. Cucurbit[n]urils (CBn) are known for a long time as the strongest synthetic binders for a wide range of (bio)organic compounds in water. However, their host-guest binding mechanism remains ambiguous despite their symmetric and simple macrocyclic structure and the wealth of literature reports. We herein report experimental thermodynamic binding parameters (ΔG, ΔH, TΔS) for CB7 and CB8 with a set of hydroxylated adamantanes, di-, and triamantanes as uncharged, rigid, and spherical/ellipsoidal guests. Binding geometries and binding energy decomposition were obtained from high-level theory computations. This study reveals that neither London dispersion interactions, nor electronic energies or entropic factors are decisive, selectivity-controlling factors for CBn complexes. In contrast, peculiar host-related solvation effects were identified as the major factor for rationalizing the unique behavior and record-affinity characteristics of cucurbit[n]urils.

As large-scale lithium-ion battery deployment accelerates, continued use of flammable organic electrolytes exacerbates issues associated with battery fires during operation and disposal. While ionic liquid-derived electrolytes promise safe, nonflammable alternatives to carbonate electrolytes, the use of ionic liquids in batteries is hindered by poor lithium transport due to the formation of long-lived lithium–anion complexes. We report the design and characterization of novel ionic liquid-inspired organic electrolytes that leverage unique self-assembly properties of molecular diamond templates, called “diamondoids”. Combining thermodynamic characterization, vibrational and magnetic spectroscopy, and single-crystal X-ray analysis, we determine that diamondoid-functionalized cations can facilitate the formation of molecularly porous phases that resist restructuring upon dissolution of lithium salts. These electrolytes can suppress lithium–anion coordination, manifesting in substantially enhanced lithium-ion mobility in the organic ion matrix. Our results provide a new paradigm for enhancing lithium mobility in solid electrolytes by tuning entropic self-assembly to enhance organic cation–anion interactions, suppress lithium–anion coordination, and increase lithium mobility in solid electrolytes.

As large-scale lithium-ion battery deployment accelerates, continued use of flammable organic electrolytes exacerbate issues associated with battery fires during operation and disposal. While ionic liquid-derived electrolytes promise safe, nonflammable alternatives to carbonate electrolytes, use of ionic liquids in batteries is hindered by poor lithium transport due to formation of long-lived lithium-anion complexes. We report the design and characterization of novel ionic liquid-inspired organic electrolytes that leverage unique self-assembly properties of molecular diamond templates, called “diamondoids.” Combining thermodynamic characterization, vibrational and magnetic spectroscopy, and single-crystal X-ray analysis, we determine that diamondoid-functionalized cations can facilitate formation of molecularly porous phases that resist restructuring upon dissolution of lithium salts. These electrolytes can suppress lithium-anion coordination, manifesting in substantially enhanced lithium-ion mobility in the organic ion matrix. Our results provide a new paradigm for enhancing lithium mobility in solid electrolytes by tuning entropic self-assembly to enhance organic cation-anion interactions, suppress lithium-anion coordination, and increase lithium mobility in solid electrolytes.