Complete selection of a self-assembling homo- or hetero-cavitand cage via metal coordination based on ligand tuning

Kenji Kobayashi; Yoshifumi Yamada; Masamichi Yamanaka; Yoshihisa Sei; Kentaro Yamaguchi

doi:10.1021/ja0465799

Complete selection of a self-assembling homo- or hetero-cavitand cage via metal coordination based on ligand tuning

J Am Chem Soc. 2004 Nov 3;126(43):13896-7. doi: 10.1021/ja0465799.

Authors

Kenji Kobayashi¹, Yoshifumi Yamada, Masamichi Yamanaka, Yoshihisa Sei, Kentaro Yamaguchi

Affiliation

¹ Department of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan.

PMID: 15506730
DOI: 10.1021/ja0465799

Abstract

Selective formation of a homo- or hetero-cavitand cage via metal-coordination, by using tetra(4-pyridyl)-cavitand (1), tetrakis(4-pyridylethynyl)-cavitand (2), or tetrakis(4-cyanophenyl)-cavitand (3) as deep cavitand ligands and Pd(dppp)(OTf)2 (4) as a connector, has been investigated by 1H NMR and CSI-MS. When the cavitand and 4 were mixed in CDCl3 in a 2:4 molar ratio, 1 gave a complicated mixture, whereas 2 or 3 formed a homo-cavitand cage {2(2).4[Pd(dppp)]}8+.8(TfO-) (5) or {2(3).4[Pd(dppp)]}8+.8(TfO-) (6), respectively, as a single species. In a 1:1:4 mixture of 2, 3, and 4, homo-cavitand cages 5 and 6 were observed in a 1:1 ratio. In marked contrast, a mixture of 1, 3, and 4 in a 1:1:4 ratio was exclusively self-assembled into a hetero-cavitand cage {1.3.4[Pd(dppp)]}8+.8(TfO-) (7). The selectivity for the self-assembly of the homo- or hetero-cavitand cage via metal coordination would arise from a combination of factors such as coordination ability and steric demand of cavitand ligands.