Synthesis and supramolecularity of C-phenylcalix[4] pyrogallolarenes: Temperature effect on the formation of different isomers

A family of C-(4-substituted phenyl)calix[4]pyrogallolarene hosts was synthesized through the acid-catalyzed condensation of pyrogallol with a series of para-substituted benzaldehydes at different reaction temperatures. The effect of reaction temperature and substitution pattern on the benzaldehyde was investigated. Different isomers of C-(4-substituted phenyl)calix[4] pyrogallolarene were observed at room temperature or under reflux conditions as indicated in the solid-state structures of compounds 1 and 2. The conformational rigidity of the resulting C-(4-substituted phenyl)calix[4]pyrogallolarene was also affected by the halogen substitution. X-ray analyses of single crystals of C-(4-substituted phenyl)calix[4]pyrogallolarene revealed the formation of inclusion complexes with different stoichiometries.