Versatile pyridine-2,6-bis-tetrazolate scaffolds for the formation of highly luminescent lanthanide complexes?

Dalton Transactions Pub Date: 2016-01-08 DOI: 10.1039/C5DT04811G

Abstract

Here we report the straightforward synthesis of the ligands Ltz, LtzC8, LtzPEG, LtzAnis and L[triple bond, length as m-dash]Anis presenting the same pyridine-bistetrazolate (pytz, L) chelating scaffold but different substituents on the para position of the pyridine ring. Its substitution allows the tuning of the solubility of the LnIII complexes [Ln(Li)3]3?. These new ligands form homoleptic nona-coordinated LnIII complexes of analogous structure and comparable stability in water and methanol. The derivatization of the para position with triazole and substituted triazole groups does not lead to a significant shift of the absorption window, but a shift of 40 nm is observed in ligand L[triple bond, length as m-dash]Anis due to the presence of the p-ethynyl anisole fragment. The LtzX series sensitize well, both the Eu and the Tb ions with quantum yields up to 98% for Tb and 43% for Eu, while the ligand L[triple bond, length as m-dash]Anis sensitizes well Eu (QY of 48%) but cannot sensitize Tb due to the position of its triplet state.

Graphical abstract: Versatile pyridine-2,6-bis-tetrazolate scaffolds for the formation of highly luminescent lanthanide complexes
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