358978-76-4Relevant articles and documents
Diverse synthesis of novel bisterpyridines via Suzuki-type cross-coupling
Fu, She Han,Higuchi, Masayoshi,Kurth, Dirk G.
, p. 559 - 562 (2007)
A new protocol is presented for the synthesis of novel bisterpyridine derivatives using palladium-catalyzed Miyaura- and Suzuki-type cross-couplings as the key reactions. This protocol is quick, efficient, mild, and broadly applicable for the construction of versatile bisterpyridines by symmetric and unsymmetric introduction of various substituants in the pyridine rings as well as by tuning the spacers for bridging the two terpyridine moieties.
Remarkable tuning of the coordination and photophysical properties of lanthanide ions in a series of tetrazole-based complexes
Andreiadis, Eugen S.,Demadrille, Renaud,Imbert, Daniel,Pecaut, Jacques,Mazzanti, Marinella
supporting information; experimental part, p. 9458 - 9476 (2010/04/05)
A series of seven new tetrazole-based ligands (Ll, L3-L8) containing terpyridine or bipyridine chromophores suited to the formation of luminescent complexes of lanthanides have been synthesized. All ligands were prepared from the respective carbonitriles by thermal cycloaddition of sodium azide. The crystal structures of the homoleptic terpyridine-tetrazolate complexes [Ln(Li)2]NHEt3 (Ln = Nd, Eu, Tb for i = 1, 2; Ln = Eu for i = 3, 4) and of the monoaquo bypyridine-tetrazolate complex [Eu(H 2O)(L7)2]NHEt3 were determined. The tetradentate bipyridine-tetrazolate ligand forms nonhelical complexes that can contain a water molecule coordinated to the metal. Conversely, the pentadentate terpyridine-tetrazolate ligands wrap around the metal, thereby preventing solvent coordination and forming chiral double-helical complexes similarly to the analogue terpyridine-carboxylate. Proton NMR spectroscopy studies show that the solid-state structures of these complexes are retained in solution and indicate the kinetic stability of the hydrophobic complexes of terpyridine-tetrazolates. UV spectroscopy results suggest that terpyridine-tetrazolate complexes have a similar stability to their carboxylate analogues, which is sufficient for their isolation in aerobic conditions. The replacement of the carboxylate group with tetrazolate extends the absorption window of the corresponding terpyridine- (≈ 20nm) and bipyridine-based (25 nm) complexes to-wards the visible region (up to 440 nm). Moreover, the substitution of the terpyridine-tetrazolate system with different groups in the ligand series L3-L6 has a very important effect on both absorption spectra and luminescence efficiency of their lanthanide complexes. The tetrazole-based ligands Ll and L3-L8 sensitize efficiently the luminescent emission of lanthanide ions in the visible and near-IR regions with quantum yields ranging from 5 to 53 % for Eu III complexes, 6 to 35 % for Tb1" complexes, and 0.1 to 0.3% for NdIII complexes, which is among the highest reported for a neodymium complex. The luminescence efficiency could be related to the energy of the ligand triplet states, which are strongly correlated to the ligand structures.
