Constructing a Nonfluorescent Conformation of AIEgen: A Tetraphenylethene Embedded in the Calix[4]arene's Skeleton

Two novel 1,1‐diphenylmethylidene decorated calix4]arenes, ( Calix‐DPE(OCH₃)₄ and Calix‐DPE(OH)₄ ), were designed and prepared. The tetraphenylethene (TPE) unit is embedded in the calix4]arenes skeleton, so the conformation of tetraphenylethene unit is significantly affected by the conformation of calix4]arene. Unlike the Calix‐DPE(OCH₃)₄ , the Calix‐DPE(OH)₄ does not show the aggregation‐induced emission (AIE) phenomena in solution or the crystal state because of the presence of intramolecular hydrogen bonding, which leads to a cone conformation for the calix4]arene skeleton in which the embedded phenyl rings of the TPE have to take an almost perpendicular configuration to the C=C bond. This result provides direct evidence that the maximal cross‐chromophore π‐conjugation within the tetraphenylethene is one of the prerequisites of switching on its AIE. This offers the possibility of switching the emission of TPE by conformation changes.