TY - JOUR
T1 - Lanthanide-nota chelates as aqueous shift reagents
T2 - Interaction with cyclopropane carboxylic acid
AU - Geraldes, C. F G C
AU - Singh, M.
AU - Sherry, A. D.
N1 - Funding Information:
This investigation was supported by Grant AT-584 from the Robert A. Welch Foundation and by a NATO Research Grant No. 0345/82. C.F.G.C. Geraldes acknowledgess upport from INIC, Portugal, and M. Singh is grateful to Guru Nanak Dev University for study leave.
PY - 1985/10
Y1 - 1985/10
N2 - Lanthanide-induced shift data are presented for cyclopropanecarboxylic acid (CPCA) binding to nine lanthanide-nota (nota is the axially symmetric macrocyclic triaza ligand 1,4,7-triazacyclonionane-N,N′N″-triacetic acid) chelates at pH 6, 25 °C and 70 °C. The contact and pseudocontact contributions to the observed proton and carbon shifts have been separated by linear regression analysis. Plots of the data in two linear forms show a break at Dy in the lanthanide series. Possible sources of this break are discussed with the help of measured proton and carbon relaxation rates of CPCA bound to five different lanthanide chelates, and comparison with similar data for CPCA bonding to the lanthanide-ethylenediaminetetraacetate chelates. This work shows that the pseudocontact shifts induced by Ln(nota) chelates in the CPCA 1H and 13C nuclei conform to the axial symmetry model, making these chelates potentially very useful as conformational probes in biological systems.
AB - Lanthanide-induced shift data are presented for cyclopropanecarboxylic acid (CPCA) binding to nine lanthanide-nota (nota is the axially symmetric macrocyclic triaza ligand 1,4,7-triazacyclonionane-N,N′N″-triacetic acid) chelates at pH 6, 25 °C and 70 °C. The contact and pseudocontact contributions to the observed proton and carbon shifts have been separated by linear regression analysis. Plots of the data in two linear forms show a break at Dy in the lanthanide series. Possible sources of this break are discussed with the help of measured proton and carbon relaxation rates of CPCA bound to five different lanthanide chelates, and comparison with similar data for CPCA bonding to the lanthanide-ethylenediaminetetraacetate chelates. This work shows that the pseudocontact shifts induced by Ln(nota) chelates in the CPCA 1H and 13C nuclei conform to the axial symmetry model, making these chelates potentially very useful as conformational probes in biological systems.
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U2 - 10.1016/0022-5088(85)90030-X
DO - 10.1016/0022-5088(85)90030-X
M3 - Article
AN - SCOPUS:0043034604
SN - 0022-5088
VL - 112
SP - 255
EP - 261
JO - Journal of The Less-Common Metals
JF - Journal of The Less-Common Metals
IS - 1-2
ER -