Calix[n]azanediyldibenzoate: Intramolecular Hydrogen Bond-Assisted Synthesis, Acidichromism, and Oriented Self-Assembly

Here, intramolecular hydrogen bond (IMHBs)-induced rigidity is used for the first time to synthesize macrocyclic arenes. Calix[n]azanediyldibenzoates (C[n]A, where n = 3, 4, or 5) are synthesized through a one-step condensation reaction between dimethyl 2,2′-azanediyldibenzoate and paraformaldehyde. Compared to the monomer, the macrocycles exhibit a fast and significant acidochromic response due to the intramolecular charge transfer that is boosted by the synergistic effect of their adsorption and protonation. In particular, the specific 1,2-alternate conformer of C[4]A allows it to assemble into a one-dimensional channel in a portal to portal mode, which can be used for the oriented assembly of aromatic aldehydes. This study offers a new perspective for designing novel macrocyclic arenes and provides an important supramolecular example for stimulus-responsive materials and manipulating crystal orientation.