Orientational isomerism controlled by the difference in electronic environments of a self-assembling heterodimeric capsule.
Tetrakis(4-hydroxyphenyl)-cavitand 1 and tetra(4-pyridyl)-cavitand 2 self-assemble into a heterodimeric capsule 1.2 via four ArOH...pyridyl hydrogen bonds in CDCl3. The 1.2 expresses the orientational isomerism of an encapsulated unsymmetrical guest with high orientational selectivity because the electronic environment of the 1 unit is different from that of the 2 unit. For p-ethoxyiodobenzene and 2-iodo-6-methoxynaphthalene encapsulated in 1.2, the iodo group is specifically oriented to the cavity of the 2 unit. The orientational isomeric selectivity for methyl p-acetoxybenzoate and methyl p-ethoxybenzoate within 1.2 is 1:0.11 and 1:<0.05, respectively, wherein the methyl ester group is preferentially oriented to the cavity of the 2 unit. The delicate balance among electrostatic potential repulsion, CH-pi interaction, or CH-halogen (halogen-pi) interaction, in 1.2-guest assembly influences the orientational isomeric selectivity of unsymmetrical guests within 1.2.
Kobayashi
Kenji
K
Department of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan. skkobay@ipc.shizuoka.ac.jp
Kitagawa
Ryosuke
R
Yamada
Yoshifumi
Y
Yamanaka
Masamichi
M
Suematsu
Takako
T
Sei
Yoshihisa
Y
Yamaguchi
Kentaro
K
D019281:Dimerization; D004583:Electrons; D004988:Ethers, Cyclic / Q000737:chemistry; D006860:Hydrogen Bonding; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D049329:Nanostructures / Q000737:chemistry*; D012118:Resorcinols / Q000737:chemistry
D004988:Ethers, Cyclic; D012118:Resorcinols; C442939:cavitand