Cyclobenzoin Esters as Hosts for Thin Guests.

Cyclotetrabenzoin esters can host terminal triple bonds of alkynes and nitriles in their cavities, as revealed by cocrystal structures of four such complexes. Within cyclotetrabenzoin cavities, π-clouds of triple bonds establish favorable and virtually equidistant interactions with the four aromatic walls of the cyclotetrabenzoin skeleton. Binding is selective for aliphatic nitriles and terminal alkynes, with their aromatic counterparts residing outside of the cyclotetrabenzoin cavity.