Crystal structure of a mono-bridged calix[4]arene

Abstract

The title compound, 52-[(5-bromopentyl)oxy]-12,114,35,55-tetra-tert-butyl-17,18,19,110-tetrahydro-16H,116H-1(4,12)-dibenzo[b,e][1,7]dioxacyclododecina-3,5(1,3)-dibenzenacyclohexaphan-32-ol, C54H73BrO4, was synthesized from the reaction of tert-butylcalix[4]arene with 1,5-dibromopentane using K2CO3 in CH3CN. The structure consists of a calixarene unit with a five-carbon bridge connecting two proximal phenolic O atoms, and with a bromopentoxy chain on one of the remaining phenolic O atoms. The calixarene unit was found to have a flattened cone conformation with no solvent (or other guest) molecule observed in the cavity. Two of the opposite phenyl rings lean outwards with fold angles of 136.2 (1) and 133.0 (1)° between the rings and the plane of the bridging methylene C atoms, while the other two opposite rings form fold angles of 83.27 (9) and 105.46 (9)°. There is considerable disorder in this molecule. One of the tert-butyl groups is disordered over two conformations with occupancies of 0.527 (5) and 0.473 (5). The bromopentoxy chain is disordered over three configurations with occupancies of 0.418, 0.332 and 0.250. The five-carbon bridge connecting two proximal phenolic O atoms is disordered over two conformations with occupancies of 0.537 (7) and 0.463 (7).

Keywords

• crystal structure
• calix[4]arene
• bridged calix[4]arene
• flattened cone conformation
• bromopentoxy chain
• hydrogen bonding