Chiroptical properties of cation complexes of chiral phenazino-18-crown-6 ether-type hosts

Szilvia Szarvas, Luca Szalay, Elemér Vass, Miklós Hollósi, Erika Samu, Péter Huszthy

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Herein we report CD spectroscopic studies on complexes of (R,R)-dimethyl-, (R,R)-diisobutyl-, and (S,S)-di-sec-butyl-phenazino-18-crown-6 ligands (Scheme 1) with selected alkali (Na+, K+), alkaline earth (Mg 2+, Ca2+), and transition-metal (Ag+, Zn 2+, Ni2+, Cd2+, Pb2+) cations. The complexation was monitored in the 300- to 240-nm region of the CD spectra comprising mainly the 1Bb band of the heteroaromatic subunit. The CD spectra of the complexes showed an unexpected diversity. In the most characteristic 1Bb spectral region, the number, position, and intensity of band (s) depend not only on the heteroaromatic subunit and the size of the substituents but also on the diameter, ion strength, and coordination geometry of the cation. The appearance of two weak 1Bb CD bands (type-I spectra) with the sign pattern of the host is an indication of two complexes of comparable stability. The "type-II" spectra differ from that of the host in the number, sign pattern, and intensity of the bands. Complexes of transition-metal cations generally show CD spectra with more intense bands. The CD spectra of complexes of (S,S)-di-sec-butyl-phenazino-18-crown-6 ligand with Na+, K +, and Pb2+ (type III) strongly suggest exciton coupling caused by the closeness of the heteroaromatic rings of two 1:1 complex molecules.

Original languageEnglish
Pages (from-to)345-351
Number of pages7
JournalChirality
Volume17
Issue number6
DOIs
Publication statusPublished - Jul 21 2005

Keywords

  • CD
  • Chiral crown ethers
  • Circular dichroism
  • Exciton chirality
  • Metal ion binding
  • Phenazino chromophores
  • Supramolecular complexes

ASJC Scopus subject areas

  • Analytical Chemistry
  • Catalysis
  • Pharmacology
  • Drug Discovery
  • Spectroscopy
  • Organic Chemistry

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