Molecular conformations of the three trimers in complex (1), with displacement ellipsoids shown at 50% probability for non-H atoms. The atomic labelling is also shown. Trimer (1a) is formed from 4-aba (C), crown ether (A) and 4-aba (G). Trimer (1b) is formed from 4-aba (D), crown ether (H) and 4-aba (E). Trimer (1c) is formed by 4-aba (F), crown ether (I) and 4-aba (B). C atoms are coloured green, O red, N blue and H grey.