Restoration of Catalytic Activity by Replacement of a Coordinated Amide Group:  Synthesis and Laser-Induced Luminescence Studies of the Phosphate Diester Transesterification Catalyst [Eu(NBAC)]³⁺

Abstract

The europium(III) complex of the octadentate tetraamide ligand is inactive as a catalyst for phosphate diester transesterification or for RNA cleavage. Replacement of one of the amide coordinating groups to form a new heptadentate ligand yields a europium(III) complex ([Eu(NBAC)]3+) that is a very active catalyst for phosphate diester transesterification at 37 °C, pH 7.40. Laser-induced luminescence is used to study the number of bound water molecules and self-association of the [Eu(NBAC)]3+ complex as well as the dissociation of the complex in the presence of competing ligands.

Solid State and Solution Dynamics of Pyridine Based Tetraaza-Macrocyclic Lanthanide Chelates Possessing Phosphonate Ligating Functionality (Ln-PCTMB): Effect on Relaxometry and Optical Properties

“…To probe the extent of dimerization in aqueous solution the Stern-Volmer quenching of EuPCTMB by NdPCTMB was assessed using a similar procedure to that reported by Morrow et. al 47. Stern-Volmer quenching constants of K SV τ = 1101 ± 61 M −1 and K SV Φ = 40780 ± 2531 M −1 were thus obtained.…”

Structure, Dynamics, and Computational Studies of Lanthanide‐Based Contrast Agents

“…These complexes show potential as artificial nucleases, NMR shift reagents for anions in aqueous solution and various chiral Eu 3+ and Tb 3+ complexes are of interest as emissive chiral probes in biological media [393][394][395][396][397][398][399][400][401]. Furthermore, the N-substituted tetraamide derivatives (Chart 5.11) have proven useful in understanding the relationship between the solution structure of the Ln 3+ complex and the water exchange rate, a critical issue in attaining optimal relaxation efficiency of CAs for MRI based on the T 1 or the chemical exchange saturation transfer (CEST) mechanisms [175,[402][403][404][405][406][407][408].…”

Synthesis and luminescence properties of a trinucleotide–europium(III) complex conjugate

“…Their properties can be tuned by varying the number of pendent amide groups and by incorporating different amide group substituents. These Ln(III) complexes are efficient catalysts for RNA cleavage, [11][12][13][14][15][16][17] are useful as luminescence sensors for anions 18, 19 and have recently been used as chemical exchange saturation transfer contrast agents for MRI. 20,21 Lanthanide(III) catalysts containing a tetraazamacrocycle and three pendent amide groups are particularly useful because they have a free amine group to facilitate attachment to recognition agents and to biopolymers.…”