Europium(III) macrocyclic complexes with alcohol pendant groups as chemical exchange saturation transfer agents

Mark Woods, Donald E. Woessner, Piyu Zhao, Azhar Pasha, Meng Yin Yang, Ching Hui Huang, Olga Vasalitiy, Janet R. Morrow, A. Dean Sherry

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55 Scopus citations

Abstract

Paramagnetic lanthanide(III) complexes that contain hyperfine-shifted exchangeable protons offer considerable advantages over diamagnetic molecules as chemical exchange saturation transfer (CEST) agents for MRI. As part of a program to investigate avenues to improve the sensitivity of such agents, the CEST characteristics of europium(III) macrocyclic complexes having appended hydroxyethyl groups were investigated. The CEST spectrum of the asymmetrical complex, EuCNPHC3+, shows five distinct peaks for each magnetically nonequivalent exchangeable proton in the molecule. The CEST spectra of this complex were fitted to NMR Bloch theory to yield exchange rates between each of six exchanging proton pools (five on the agent plus bulk water). Exchange between the Eu3+-bound hydroxyl protons and bulk water protons was slow in dry acetonitrile but accelerated incrementally upon stepwise addition of water. In pure water, exchange was too fast to observe a CEST effect. The utility of this class of europium(III) complex for CEST imaging applications is ultimately limited by the small chemical shifts induced by the hydroxyl-appended ligands of this type and the resulting small Δωvalues for the exchangeable hydroxyl protons.

Original languageEnglish (US)
Pages (from-to)10155-10162
Number of pages8
JournalJournal of the American Chemical Society
Volume128
Issue number31
DOIs
StatePublished - Aug 9 2006

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Woods, M., Woessner, D. E., Zhao, P., Pasha, A., Yang, M. Y., Huang, C. H., Vasalitiy, O., Morrow, J. R., & Sherry, A. D. (2006). Europium(III) macrocyclic complexes with alcohol pendant groups as chemical exchange saturation transfer agents. Journal of the American Chemical Society, 128(31), 10155-10162. https://doi.org/10.1021/ja061498t