Molecular Upconversion in Water in Heteropolynuclear Supramolecular Tb/Yb Assemblies.

Piling up excited states to reach upconversion (UC) is severely restricted by vibrational quenching mechanisms, especially when one looks at discrete molecular entities in solution. By carefully controlling the supramolecular assembly processes resulting from the strong electrostatic interactions between negatively charged Yb complexes and Tb cations in aqueous solutions, we engineered the formation of heteropolynuclear complexes of [(YbL)Tb ] compositions ( x = 1 and 2). These edifices display a phenomenon of cooperative photosensitization UC with green emission of the Tb cations upon NIR excitation at 980 nm in the Yb absorption band.

Formation of Mono- and Polynuclear Luminescent Lanthanide Complexes based on the Coordination of Preorganized Phosphonated Pyridines.

A series of polynuclear assemblies based on ligand L (1,4,7-tris[hydrogen (6-methylpyridin-2-yl)phosphonate]-1,4,7-triazacyclononane) has been developed. The coordination properties of ligand L with Ln (Ln = La, Eu, Tb, Yb, Lu) have been studied in water (pH = 7.0) and in DO (pD = 7.