New applications of crown ethers. X.1) 13CNMR relaxation times study of cation-binding behavior of monoazacrown ethers and Bis(monoazacrown ether)s

G. X. He, T. Imato, N. Ishibashi, S. Shinkai, T. Matsuda

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Abstract

13C NMR relaxation times (T1s) have been determined for monoazacrown ethers (CA15C5 and CA18C6) and bis(monoazacrown ether)s (BCA15C5, BCA18C6, BOA15C5, and BOA18C6) in the absence and presence of Na+ and K+ ions. For the monoazacrown ethers with heptyl side chain and the bis(monoazacrown ether)s with pentamethylene bridge chain marked changes in T1 values are observed upon the complexation, and the changes are dependent on the cation and on the structure of the ligands. The complexation with Na+ ion can give a larger effect on the T1 values for the bis(monoazacrown ether)s of 15- and 18-membered rings, especially on the mobility of the bridging chain carbons, which is indicative of the formation of an intramolecular sandwich complex. On the other hand, the present T1 study again shows the prominent effect of the oxygen in the bridging chain on the complexation of BOA15C5 and BOA18C6. Small differences in T1 values obtained between Na+ complexes and K+ complexes of these two bis(crown ether)s suggest that the complexes take an analogous partial structure for the two cations.

Original languageEnglish
Pages (from-to)401-406
Number of pages6
JournalBulletin of the Chemical Society of Japan
Volume63
Issue number2
DOIs
Publication statusPublished - Jul 25 1990

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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