Tetrazine as an amusing π-receptor has been incorporated into a novel type of
macrocyclic host molecules named coronarenes by Wang and coworkers [28]. The
existence of tetrazine component in the macrocyclic backbone rendered the molecules electron-deficient property. As a representative example, O 6 -corona[3]arene[3]
tetrazine formed a 1:3 complex with Et 4 NCl in solid state. Each of the three chlorides
in the complex located above each tetrazine centroid at a distance of 3.06–3.20 Å,
forming typical anion-π interactions (Fig. 8).
It is also worth noting that anion-π interactions were detected as modulations of
stronger non-covalent interactions such as hydrogen bonding [29, 30] and ion-dipole
interaction [31]. Albrecht and coworkers reported the binding of pentafluorobenzamide toward bromide through cooperative H-bonding and anion-π interaction [29]. Single crystal structure demonstrated that bromide located above the
plane of pentafluorobenzene ring and concurrently formed hydrogen bonding
Fig. 7 Anion-π interaction between a NDI-containing triangular cage and I 3
À anion by Stoddart
and coworkers
Fig. 8 Anion-π interactions between corona[3]arene[3]tetrazine 4 and chlorides by Wang and
coworkers
10 Application of Anion-π Interaction on Supramolecular Self-Assembly
259
macrocyclic host molecules named coronarenes by Wang and coworkers [28]. The
existence of tetrazine component in the macrocyclic backbone rendered the molecules electron-deficient property. As a representative example, O 6 -corona[3]arene[3]
tetrazine formed a 1:3 complex with Et 4 NCl in solid state. Each of the three chlorides
in the complex located above each tetrazine centroid at a distance of 3.06–3.20 Å,
forming typical anion-π interactions (Fig. 8).
It is also worth noting that anion-π interactions were detected as modulations of
stronger non-covalent interactions such as hydrogen bonding [29, 30] and ion-dipole
interaction [31]. Albrecht and coworkers reported the binding of pentafluorobenzamide toward bromide through cooperative H-bonding and anion-π interaction [29]. Single crystal structure demonstrated that bromide located above the
plane of pentafluorobenzene ring and concurrently formed hydrogen bonding
Fig. 7 Anion-π interaction between a NDI-containing triangular cage and I 3
À anion by Stoddart
and coworkers
Fig. 8 Anion-π interactions between corona[3]arene[3]tetrazine 4 and chlorides by Wang and
coworkers
10 Application of Anion-π Interaction on Supramolecular Self-Assembly
259