Synthesis and characterization of a series of macrocyclic chelates containing O and N donors

Prospects for use as NMR shift agents for alkali-metal cations

R. Merritt Sink, Douglas C. Buster, A. Dean Sherry

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

A new series of polyoxa tetraaza macrocyclic tetraacetates have been prepared and characterized. These derivatives chelate lanthanides and transition-metal ions in the tetraaza tetraacetate portion of the macrocycle, leaving the polyoxa portion available for binding with alkali-metal cations. The protonation constants and metal-binding properties of these chelates have been investigated and compared to those of the parent molecule 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Molecular mechanics calculations were performed to estimate the polyoxa cavity sizes, and these results were compared to those of the crown ether series. The Dy3+, Ni2+, and Co2+ complexes were examined for their ability to induce a paramagnetic shift in the 23Na+ NMR resonance of aqueous NaCl at pH 7. The Dy3+ complex formed with the tetraoxa tetraaza macrocycle (O4N4) produced the largest 23Na paramagnetic shift, opposite in direction to that produced by Dy(DOTA)-. This verified that Na+ (and other alkali-metal cations) binds in the polyoxa cavity, orthorogonal to the presumed symmetry axis of the Dy3+ cation bound within the tetraaza tetraacetate portion of the macrocycle. Competitive titrations with Ca2+ indicate that these ligands are considerably more specific for Na+ ions than are the more common ion-pairing 23Na shift agents.

Original languageEnglish (US)
Pages (from-to)3645-3649
Number of pages5
JournalInorganic Chemistry
Volume29
Issue number19
StatePublished - 1990

Fingerprint

Alkali Metals
chelates
alkali metals
Cations
Nuclear magnetic resonance
cations
nuclear magnetic resonance
shift
synthesis
Ions
Crown Ethers
Lanthanoid Series Elements
cavities
Molecular mechanics
Protonation
Titration
titration
Transition metals
Metal ions
ethers

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Synthesis and characterization of a series of macrocyclic chelates containing O and N donors : Prospects for use as NMR shift agents for alkali-metal cations. / Sink, R. Merritt; Buster, Douglas C.; Sherry, A. Dean.

In: Inorganic Chemistry, Vol. 29, No. 19, 1990, p. 3645-3649.

Research output: Contribution to journalArticle

@article{0de9600a89f04641a93bcaafda69b069,
title = "Synthesis and characterization of a series of macrocyclic chelates containing O and N donors: Prospects for use as NMR shift agents for alkali-metal cations",
abstract = "A new series of polyoxa tetraaza macrocyclic tetraacetates have been prepared and characterized. These derivatives chelate lanthanides and transition-metal ions in the tetraaza tetraacetate portion of the macrocycle, leaving the polyoxa portion available for binding with alkali-metal cations. The protonation constants and metal-binding properties of these chelates have been investigated and compared to those of the parent molecule 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Molecular mechanics calculations were performed to estimate the polyoxa cavity sizes, and these results were compared to those of the crown ether series. The Dy3+, Ni2+, and Co2+ complexes were examined for their ability to induce a paramagnetic shift in the 23Na+ NMR resonance of aqueous NaCl at pH 7. The Dy3+ complex formed with the tetraoxa tetraaza macrocycle (O4N4) produced the largest 23Na paramagnetic shift, opposite in direction to that produced by Dy(DOTA)-. This verified that Na+ (and other alkali-metal cations) binds in the polyoxa cavity, orthorogonal to the presumed symmetry axis of the Dy3+ cation bound within the tetraaza tetraacetate portion of the macrocycle. Competitive titrations with Ca2+ indicate that these ligands are considerably more specific for Na+ ions than are the more common ion-pairing 23Na shift agents.",
author = "Sink, {R. Merritt} and Buster, {Douglas C.} and Sherry, {A. Dean}",
year = "1990",
language = "English (US)",
volume = "29",
pages = "3645--3649",
journal = "Inorganic Chemistry",
issn = "0020-1669",
publisher = "American Chemical Society",
number = "19",

}

TY - JOUR

T1 - Synthesis and characterization of a series of macrocyclic chelates containing O and N donors

T2 - Prospects for use as NMR shift agents for alkali-metal cations

AU - Sink, R. Merritt

AU - Buster, Douglas C.

AU - Sherry, A. Dean

PY - 1990

Y1 - 1990

N2 - A new series of polyoxa tetraaza macrocyclic tetraacetates have been prepared and characterized. These derivatives chelate lanthanides and transition-metal ions in the tetraaza tetraacetate portion of the macrocycle, leaving the polyoxa portion available for binding with alkali-metal cations. The protonation constants and metal-binding properties of these chelates have been investigated and compared to those of the parent molecule 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Molecular mechanics calculations were performed to estimate the polyoxa cavity sizes, and these results were compared to those of the crown ether series. The Dy3+, Ni2+, and Co2+ complexes were examined for their ability to induce a paramagnetic shift in the 23Na+ NMR resonance of aqueous NaCl at pH 7. The Dy3+ complex formed with the tetraoxa tetraaza macrocycle (O4N4) produced the largest 23Na paramagnetic shift, opposite in direction to that produced by Dy(DOTA)-. This verified that Na+ (and other alkali-metal cations) binds in the polyoxa cavity, orthorogonal to the presumed symmetry axis of the Dy3+ cation bound within the tetraaza tetraacetate portion of the macrocycle. Competitive titrations with Ca2+ indicate that these ligands are considerably more specific for Na+ ions than are the more common ion-pairing 23Na shift agents.

AB - A new series of polyoxa tetraaza macrocyclic tetraacetates have been prepared and characterized. These derivatives chelate lanthanides and transition-metal ions in the tetraaza tetraacetate portion of the macrocycle, leaving the polyoxa portion available for binding with alkali-metal cations. The protonation constants and metal-binding properties of these chelates have been investigated and compared to those of the parent molecule 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Molecular mechanics calculations were performed to estimate the polyoxa cavity sizes, and these results were compared to those of the crown ether series. The Dy3+, Ni2+, and Co2+ complexes were examined for their ability to induce a paramagnetic shift in the 23Na+ NMR resonance of aqueous NaCl at pH 7. The Dy3+ complex formed with the tetraoxa tetraaza macrocycle (O4N4) produced the largest 23Na paramagnetic shift, opposite in direction to that produced by Dy(DOTA)-. This verified that Na+ (and other alkali-metal cations) binds in the polyoxa cavity, orthorogonal to the presumed symmetry axis of the Dy3+ cation bound within the tetraaza tetraacetate portion of the macrocycle. Competitive titrations with Ca2+ indicate that these ligands are considerably more specific for Na+ ions than are the more common ion-pairing 23Na shift agents.

UR - http://www.scopus.com/inward/record.url?scp=0000906897&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000906897&partnerID=8YFLogxK

M3 - Article

VL - 29

SP - 3645

EP - 3649

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 19

ER -