Mono(pyridine-N-oxide) analog of DOTA as a suitable organic reagent for a sensitive and selective fluorimetric determination of Ln(III) ions

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 …”

“…Another advantage of IQCA is a lower self-quenching effect [ 28 ]. All these factors lead to an increase in the quantum yield of about two orders of magnitude (see Figure 1 d, [ 23 , 28 , 29 ]).…”

“…In addition, the m / z pattern typical for Ln(III) ions with more natural isotopes was found in the mass spectra ( Figures S1–S3 ). Secondly, time-resolved luminescence spectroscopy showed the decrease of the number of water molecules (Δ q = 0.8) calculated from luminescence decays for the [Eu(DO3A)] and [Eu(DO3A)(IQCA)] complexes (0.372 ms [ 23 ] vs. 0.512 ms—see Figure 6b, leading to the q values equal to 2.1 and 1.3). Further, a significant increase in the quantum yield as a consequence of the antenna effect was also observed for these complexes (0.024% [ 23 ] vs. 6.9%—estimation using [Eu(DPA) 3 ] 3− complex as standard).…”

“…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 ].…”

Visualization of Fluoride Ions In Vivo Using a Gadolinium(III)-Coumarin Complex-Based Fluorescence/MRI Dual-Modal Probe

“…By virtue of the extremely high Ln–fluoride affinity, the coordinated molecules or fluorophores of Ln complexes can be displaced by fluoride ions. As the result of this interaction, the liberation of the coordinated ligands may lead to the changes in several observable signals, such as colour [31], fluorescence and MR [32,33]. Due to their high magnetic moment and symmetric electronic ground state, gadolinium(III) complexes have been frequently chosen as MRI contrast agents [34].…”