Synthesis of Open‐Cage Fullerenes Containing a H‐Bond between the Encapsulated Water Molecule and the Amide Moiety on the Rim of the Orifice

Further hydrolysis of an open‐cage fullerene derivative with an epoxy moiety on the rim of the orifice led to the formation of a new open‐cage fullerene with a 17‐membered orifice and an amide group directly above the orifice. The water encapsulation ratio in the new open‐cage compound reached 100 % as a result of heating with water at 80 °C. The amide group above the orifice completely blocks the opening and forms H‐bond with the trapped water molecule. Single crystal X‐ray structure shows that the bond length between the trapped water oxygen and the amide oxygen is 2.859 Å. The H‐bond energy is about −3.83 kcal/mol as shown by theoretical calculation.