Isomerization kinetics of lanthanide(III) complexes with the pendant-arm macrocyclic ligand 1,4,7,10-tetrakis(2-hydroxyethyl)-1,4,7,10-tetraazacyclododecane

Abstract

Isomerization kinetics of lanthanide(III) complexes with the pendantarm macrocyclic ligand 1,4,7,10-tetrakis(2-hydroxyethyl)-1,4,7,10tetraazacyclododecane †

Cerium(III), Europium(III), and Ytterbium(III) Complexes with Alcohol Donor Groups as Chemical Exchange Saturation Transfer Agents for MRI

“…Four resonances arise from the protons in the macrocycle backbone, four resonances arise from the protons on the ethylene portion or methyl group of the pendent arms and one resonance arises from the hydroxyl protons (Figure 1). The simplicity of these 1 H NMR spectra is consistent with a single enantiomeric pair in solution 10,14. As shown previously, Ln( THED ) 3+ complexes form a pair of enantiomers that are either in the form of a twisted square antiprism or a square antiprism 14.…”

“…The simplicity of these 1 H NMR spectra is consistent with a single enantiomeric pair in solution 10,14. As shown previously, Ln( THED ) 3+ complexes form a pair of enantiomers that are either in the form of a twisted square antiprism or a square antiprism 14. Ln( S-THP ) 3+ complexes have an additional element of chirality in the pendent propanol group that gives a single diastereomer in solution,11 the twisted square antiprism 22…”

“…One element arises from pendent group orientation (clockwise or counterclockwise) and the other from the two conformations of the cyclen ring. This gives rise to four stereoisomers which exist as two enantiomeric pairs14-18. For amide pendent group macrocycles, two diastereomers are generally observed in solution by NMR spectroscopy15,19,20 and by Eu(III) excitation luminescence spectroscopy21.…”

An Efficient Route to Symmetrically and Unsymmetrically Substituted Azamacrocyclic Ligands

“…Investigations into the synthesis of larger N 3 -and N 4 -azamacrocycles and 17 [26] were prepared as reported and then reacted with tosylamide or benzylamine. Cyclisation reactions using tosylamide proved to be incredibly efficient for both the 10-membered N 3 -macrocycle 15a [27] and the cyclen derivative 18a, [28] which were both isolated in 95% yield. Unfortunately, when the analogous reactions were investigated with benzylamine the results were less impressive.…”

BINOL Macrocycle Derivatives: Synthesis of New Dinaphthyl Sulfide Aza Oxa Thia Crowns (Lariats)

“…Chloroamide derivatives (4-7) were synthesized from the reaction of corresponding amine and chloroacetyl chloride in the presence of triethylamine as base and in dichloromethane as solvent (Scheme 2) [40][41][42]45], the lariat azacrowns (8)(9)(10)(11) were synthesized from the reaction of chloroamides (4-7) and macrocycle (3). is reaction was carried out via a modi�ed procedure in the presence of sodium carbonate and catalytic amounts of sodium iodide in CH CN/DMF (10 : 1) at room temperature (Scheme 3) [46][47][48].…”