Solid‐State Emissive Pillar[6]arene Derivative Having Alternate Methylene and Nitrogen Bridges.

Macrocyclic arenes show conformational adaptability, which allows host–guest complexations with the size‐matched guest molecules. However, their emission properties are often poor in the solid states due to the self‐absorption. Herein, we newly synthesized pillar[6]arene derivatives having alternate methylene and nitrogen bridging structures. Solvatochromic study reveals that the nitrogen‐embedding into the cyclic structures can strengthen the intramolecular charge transfer (CT) nature compared to that of the linear nitrogen‐bridged precursor. Owing to the large Stokes shift in the solid state, one of the nitrogen‐embedded pillar[6]arenes shows high absolute photoluminescence quantum yield (ΦPL=0.36). Furthermore, it displays a turn‐off sensing ability toward nitrobenzene (NB) vapor; a fluorescence quenching is observed when exposed to the NB vapor. From the structural analysis before and after the exposure of NB vapor, the amorphous nitrogen‐embedded pillar[6]arene efficiently co‐crystallize with NB and formed non‐emissive intermolecular CT complexes with NB. [ABSTRACT FROM AUTHOR]