Cyclic oligo‐tetrazine–naphthalene ethers NTz2 and NTz3 were synthesized via a one‐pot nucleophilic aromatic substitution macrocyclization using 3,6‐dichlorotetrazine with 2,7‐dihydroxynaphthalene. Reaction concentration allowed selective control of ring size, affording highly symmetric, shape‐persistent macrocycles. The larger NTz3 possesses a well‐defined cavity and forms a stable 1:1 host–guest complex with C 60 , as confirmed by 1 H NMR titration and single‐crystal X‐ray diffraction analysis. Photophysical studies revealed that the ring size strongly influences excited‐state behavior: NTz3 exhibits singlet excited energy transfer from naphthalene to tetrazine units, leading to orange emission, whereas NTz2 shows bluish‐white emission essentially from the naphthalene unit. These results demonstrate the potential of tetrazine‐based macrocycles as multifunctional platforms combining molecular recognition and tunable optical properties.
Shinkawa et al. (Wed,) studied this question.