Ein Wirt innerhalb eines Wirts: Einschluss von Alkalimetallionen-Kronenether-Komplexen in einen supramolekularen [Ga4L6]12−-Cluster

Supramolecular Chemistry in Water

“…For example, the metal-organic purine triangle 78 and purine square 79 trap sulfate by means of electrostatic and multiple hydrogen-bonding interactions in D 2 O with K a = 7.2 10 4 m À1 and 9.9 10 3 m À1 , respectively. [208] The water-soluble supramolecular M 4 L 6 coordination structures 80 [210] consist of four metal atoms (M = Ga 3+ , Al 3+ , In 3+ , or Fe 3+ ) situated at the corners of a tetrahedron and bridged by six naphthalene-based bis-bidentate catechol ligands L. They possess a cavity of 300-350 3[210] which can encapsulate a variety of lipophilic cationic molecules, such as tetraalkylammonium, [211][212][213][214][215] tetraalkylphosphonium, [211,212,216,217] tropylium, [218] aromatic diazonium, [218] pyridinium, [215] cationic organometallic species, [211][212][213][219][220][221][222] and alkali-metal crown complexes [223] in water. For example, [Ga 4 L 6 ] 12À binds tetraethylphosphonium, tetraethylammonium, azoniapropellane (81), sodium [12]crown-4 (82 A + = Na + ), and cobaltocenium in aqueous solution with binding constants of 1 10 6 , 3.6 10 4 , 1.7 10 4 , 3.4 10 4 , and 1.7 10 4 m À1 , respectively.…”

“…For example, [Ga 4 L 6 ] 12À binds tetraethylphosphonium, tetraethylammonium, azoniapropellane (81), sodium [12]crown-4 (82 A + = Na + ), and cobaltocenium in aqueous solution with binding constants of 1 10 6 , 3.6 10 4 , 1.7 10 4 , 3.4 10 4 , and 1.7 10 4 m À1 , respectively. [211,223] The cages can selectively encapsulate the lipophilic part of complex molecules; for example, in the case of zwitterions 83, the cationic head is encapsulated in [Ga 4 L 6 ] 12À , while the linker to the anionic sulfonate tail passes through one of the small openings at the center of the triangular faces, thereby leaving the sulfonate substituent in water. [220] The M 4 L 6 tetrahedron has also demonstrated its ability to stabilize reactive intermediates in aqueous media.…”

Hierarchical study of mono- and multicharged imidazolium encapsulation in p-sulfonatocalix[4]arene molecular capsules

“…[2][3][4][5] The simplest form of molecule capsule is connecting two cavitands at their open ends, where these are often linked by non-covalent interaction such as hydrogen bonds [6][7][8] and/or metal-coordination. [9][10][11][12][13][14] Examples of molecular capsules formed via complementary hydrogen bonding interactions include (but are not limited to) glycoluril-based "tennis balls" and "softballs", 15,16 deep cavity octa-acid or resorcin [4]arenebased dimers, 17 and tetrol- 7 and calixpyrrole-based 18 capsules. Cone-shaped calix [4]arene-based host molecules belong to the class of cavitands and have a long history in the study of molecular recognition.…”