α-cyclodextrin dissolved in water binds methane giving crystals of a 1 : 1 complex in up to 57% yield. The binding constant was Ka = 21 (± 1.0) M−1. 3A,6A,3D,6D-dianhydro-α-cyclodextrin which has a smaller cavity than α-cyclodextrin binds methane three fold better (Ka = 75 (± 25) M−1)
