Host-guest complexation. 62. Solvophobic and entropic driving forces for forming velcraplexes, which are 4-fold, lock-key dimers in organic media

Systems have been prepared composed of aromatic groups rigidly arranged to form ∼15 by ∼20 A rectangular surfaces containing two regularly spaced protruding methyls at 3 and 9 o'clock ant two methyl-sized holes at 12 and 6 o'clock (e.g., 1). These molecules form dimers with large common surfaces in which the four methyl groups insert into the four holes. The resulting complexes have 82 to 132 intermolecular atom-to-atom contacts at van der Waals distances +0.2 A (five crystal structures)