The time-resolved fluorescence study of kinetics and thermodynamics of Eu(iii) and Tb(iii) complexes with the DO2A macrocyclic ligand

Abstract

The thermodynamics and kinetics of formation/dissociation of Eu(iii) and Tb(iii) with the H2DO2A macrocyclic ligand were studied by time-resolved fluorescence spectroscopy.

Luminescent Sensor Based on Ln(III) Ternary Complexes for NAD(P)H Detection

“…The macrocyclic ligands H 2 DO2A and H 3 DO3A, which differ in their denticity (hexadentate for DO2A 2− and heptadentate for DO3A 3− ), are capable of forming Ln(III) complexes with high thermodynamic stability and kinetic inertness [ 19 , 20 , 21 , 23 , 24 ]. The formation of these Ln(III) complexes with characteristic sharp-peak emission spectra is accompanied by an increase of Ln(III) ion luminescence intensity due to the release of water molecules coordinated to Ln(III) ion [ 24 , 28 ]: [Ln(H 2 O) 9 ] 3+ + L z − ↔ [LnL(H 2 O) 2-3 ] 3- z + (6-7) H 2 O …”

“…The most suitable ligands for the tight binding of Ln(III) ions are highly rigid macrocyclic compounds which fulfil the above-mentioned properties due to the macrocyclic effect [ 17 , 18 , 19 ]. When the coordination number of the Ln(III) ion (usually about 8–9) is equal to denticity of macrocyclic ligand, complexes with 1:1 stoichiometry are formed [ 5 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. For these reasons, Ln(III) complexes with macrocyclic ligands (mainly DOTA derivatives) are commonly utilized in medicinal chemistry as radiopharmaceuticals ( 90 Y, 153 Sm, 166 Ho, 177 Lu) [ 18 , 25 ] and contrast agents for MRI (Gd) [ 5 , 18 , 26 , 27 ].…”