Thermodynamically driven self-assembly of pyridinearene to hexameric capsules

Abstract

For the first time the formation of hexameric pyridine[4]arene capsule has been observed in gas phase, in solution and in solid state. A thermodynamic balance between capsule formation was observed, showing favour to hexamer.

Dimeric iodine(i) and silver(i) cages from tripodal N-donor ligands via the [N–Ag–N]+ to [N–I–N]+ cation exchange reaction

“…6,7 To date, various host–guest capsular assemblies have been reported using molecules such as resorcin[4]arenes, 8–11 calix[4]-arenes, 12–14 and pyridine[4]arenes. 15,16 The self-assembled capsular assemblies comprise two or more suitable preorganised molecules spontaneously forming capsular entities with either metal coordination, 17–21 or hydrogen bonding. 22,23…”

“…6,7 To date, various host-guest capsular assemblies have been reported using molecules such as resorcin [4]arenes, [8][9][10][11] calix [4]-arenes, [12][13][14] and pyridine [4]arenes. 15,16 The selfassembled capsular assemblies comprise two or more suitable preorganised molecules spontaneously forming capsular entities with either metal coordination, [17][18][19][20][21] or hydrogen bonding. 22,23 Ever since the 1990s, halogen bonding has developed into a true competitor for hydrogen bonding and other non-covalent interactions to the point that, to date, it is one of the most studied interactions in supramolecular chemistry.…”

Recent Advances in Halogen Bonded Assemblies with Resorcin[4]arenes

“…In addition, the OH groups on the upper rim can interact with guest species [12] . In the presence of suitable neutral or ionic guests, resorcinarenes have the ability to form assemblies via weak interactions such as open‐inclusion complexes, [13] dimeric capsules, [14,15] hexameric capsules, [16–18] larger supramolecular and tubular assemblies [19] …”

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

“…Although the synthesis of pyridine[4]arenes dates back to 2001 [4], their host–guest chemistry is still under-explored. Both macrocycles are concave and are known to form capsular assemblies via intermolecular hydrogen bonding [5–6]. Pyridine is significantly less electron-rich than benzene.…”

“…They are, however, on tangential positions along the capsules surface, and therefore do not significantly contribute to anion binding [8]. More recently, we were also able to demonstrate that cationic transition metal complexes can template the formation of pyridinearene hexameric capsules in the gas phase [6].…”