Synthesis and crystal structures of 5,17-di-bromo-26,28-dihy-droxy-25,27-dipropynyloxycalix[4]arene, 5,17-di-bromo-26,28-dipropoxy-25,27-dipropynyloxycalix[4]arene and 25,27-bis-(2-azido-eth-oxy)-5,17-di-bromo-26,28-di-hydroxy-calix[4]arene.

The calixarenes, 5,17-di-bromo-26,28-dihy-droxy-25,27-dipropynyloxycalix[4]arene (C 34 H 26 Br 2 O 4 , 1 ), 5,17-di-bromo-26,28-dipropoxy-25,27-dipropynyloxycalix[4]arene (C 40 H 38 Br 2 O 4 , 2 ) and 25,27-bis-(2-azido-eth-oxy)-5,17-di-bromo-26,28-di-hydroxy-calix[4]arene (C 32 H 28 Br 2 N 6 O 4 , 3 ) possess a pinched cone mol-ecular shape for 1 and 3 , and a 1,3-alternate shape for compound 2 . In calixarenes 1 and 3 , the cone conformations are additionally stabilized by intra-molecular O-H⋯O hydrogen bonds, while in calixarene 2 intra-molecular Br⋯Br inter-actions consolidate the 1,3-alternate mol-ecular conformation. The dense crystal packing of the cone dialkyne 1 is a consequence of π-π, C-H⋯π and C-H⋯O inter-actions. In the crystal of the diazide 3 , there are large channels extending parallel to the c axis, which are filled by highly disordered CH 2 Cl 2 solvent mol-ecules. Their contribution to the intensity data was removed by the SQUEEZE procedure that showed an accessible void volume of 585 Å 3 where there is room for 4.5 CH 2 Cl 2 solvent mol-ecules per unit cell. Rigid mol-ecules of the 1,3-alternate calixarene 2 form a columnar head-to-tail packing parallel to [010] via van der Waals inter-actions, and the resulting columns are held together by weak C-H⋯π contacts.