Tubular Arrangement of 1,3-Alternate Calix[4]arene with Bipyridines: A Platform for [2+2] Photocyclization

By using a 1,3-alternate conformation of calix[4]arene tetrabenzoic acid (H4CTB), a pair of 4,4'-bipyridine has been aligned forming a cocrystallized one-dimensional tubular product 1. Inspired by this result, the 1,3-alternate H4CTB has been utilized as clips to anchor the C=C bond pairs of 4,4'-bipyridylethene to give an isotypical H-bonded tubular product 2 which undergoes the solid-state photodimerization.