Metal-mediated self-assembly of pyridylcalixarenes: Prevention of intramolecular metal chelation is essential in constructing molecular capsules

Z. Zhong, A. Ikeda, M. Ayabe, S. Shinkai, S. Sakamoto, K. Yamaguchi

Research output: Contribution to journalArticlepeer-review

72 Citations (Scopus)

Abstract

To construct calixarene-based molecular capsules utilizing the pyridyl-Pd(II) interaction, reactions of cone-pyridylcalix[4]arene 3, cone-pyridylcalix[5]arene 13, and cone-pyridylcalix[4]arene bis-crown 16 with square-planar Pd(II) complex 7 were investigated. Because of the coexistence of intermolecular binding and chelate-forming intramolecular binding, the reactions of cone-pyridylcalix[4]arene 3 or cone-pyridylcalix[5]arene 13 with cis-Pd(II) complex 7 yield complicated, structure-unknown oligomers. The short dioxyethylene bridges on the lower rim of pyridylcalix-[4]arene bis-crown 16 rigidify the cone conformation and thus prohibit 16 from the intramolecular binding with a metal component. Thus, two cone-tetrapyridylcalix[4]arene bis-crown 16 and four cis-Pd(II) complex molecules self-assemble into molecular capsules that exist as a parallel/antiparallel conformer mixture in a nearly 1:1 ratio. The results demonstrated that to prevent entropically favorable intramolecular binding is essential in constructing higher capsule-like structures with calixarene building blocks by self-assembling.

Original languageEnglish
Pages (from-to)1002-1008
Number of pages7
JournalJournal of Organic Chemistry
Volume66
Issue number3
DOIs
Publication statusPublished - Feb 9 2001

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

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