Photophysical and Structural Impact of Phosphorylated Anions Associated to Lanthanide Complexes in Water

Abstract

A new ligand, LC, bis-[(6'-carboxy-2,2'-bipyridine-6-yl)]phenylphosphine oxide, in which the tridentate 6-carboxy-2,2'-bipyridyl arms are directly linked to a phenylphosphine oxide fragment, has been synthesized. The corresponding [Ln.LC]Cl.xH2O complexes (Ln = Eu, x = 4, and Tb, x = 3) were isolated from solutions containing equimolar amounts of LC and hydrated LnCl3 salts and characterized by elemental analysis, mass spectrometry, and infrared spectroscopy. The interactions of the Eu complex with various anions (AMP(2-), ADP3-, ATP,4- HPO4(2-), and NO3-) were studied by titration experiments, using UV-vis, luminescence spectroscopy, and excited-state lifetime measurements. The results are in keeping with strong interactions with the ADP3-, ATP4-, and phosphate anions in TRIS/HCl buffer (0.01 M, pH = 7.0), as revealed by the determination of the conditional stepwise association constants. These values are higher than the one determined for ligand LB, bis[(6'-carboxy-2,2'-bipyridine-6-methyl-yl)]-n-butylamine (Delta log K approximately 1-2). The interaction of complexes [Ln.LB]+ and [Ln.LC]+ with nitrate, monohydrogenophosphate, methyl phosphate (MeP2-), methyldiphosphate (MeDP3-), and methyltriphosphate (MeTP4-) anions was investigated by means of quantum mechanical (QM) calculations. The results, combined with data on the photophysical impact of the sequential competitive binding of anions to the Eu complexes in water, suggest that LB is too flexible to ensure a good coordination pocket, while the molecular structure of ligand LC stabilizes both the formation of the lanthanide complexes and its adducts with ATP.

Highly Luminescent, Neutral, Nine‐Coordinate Lanthanide(III) Complexes

“…Ziessel and co-workers have developed a number of macrocyclic ligands based on the bipyridine carboxylate architecture. [11] Multinuclear complexes using a tridentate ligand containing a bipyridine moiety and a carboxylate group have recently been reported by Mamula and co-workers [12] and nonalanthanide cluster based on a derivative of 3 by Comby et al [13] The Eu and La complexes 2b and 2g formed crystals suitable for X-ray diffraction, and the resulting molecular structure of 2b is shown in Figure 1 (2g is shown in Figure S1). Scheme 1.…”

Lanthanide Complexes and Quantum Dots: A Bright Wedding for Resonance Energy Transfer

“…Thanks to the specific spectral signature of both partners, multiplexing may become easier with possible combinations by using two lanthanide donors, such as an europium and a terbium complex, coupled to three to four specific QD acceptors within a single fluoroimmunoassay. Assemblies of cationor anion-responsive lanthanide complexes [108] at the surface of QDs would also be particularly well suited for sensing applications applied to microscopic techniques and would add the sensing ability to the well-established use of QDs for in vivo imaging techniques. [33,109,110] …”

Interfacial interactions of hard polyelectrolyte-stabilized luminescent colloids with substrates

“…From this point of view a use of luminescent lanthanide complexes as luminescent component of nanoparticles is of particular importance. It derives from unique photophysical properties of lanthanide-centered luminescence and stimuli response ability of lanthanide complexes, which have been widely applied in a development of sensing procedures [7][8][9][10]. Commonly, luminescent lanthanide assays are based on ligand or ion exchange.…”

“…Commonly, luminescent lanthanide assays are based on ligand or ion exchange. A plenty of biorelevant substrates are chelating ligands able to complex with lanthanides [8][9][10]. Literature data represent fine examples of luminescent sensing of phosphates [10] and antibiotics [11][12][13][14][15] through a sensitization of lanthanide-centered luminescence in aqueous solutions.…”