000203038 001__ 203038
000203038 005__ 20181203023646.0
000203038 0247_ $$2doi$$a10.1002/hlca.200900150
000203038 022__ $$a0018-019X
000203038 02470 $$2ISI$$a000272434000009
000203038 037__ $$aARTICLE
000203038 245__ $$aWater Stability and Luminescence of Lanthanide Complexes of Tripodal Ligands Derived from 1,4,7-Triazacyclononane: Pyridinecarboxamide versus Pyridinecarboxylate Donors
000203038 260__ $$c2009
000203038 269__ $$a2009
000203038 336__ $$aJournal Articles
000203038 520__ $$aA series of europium(III) and terbium(III) complexes of three 1,4,7-triazacyclononane-based pyridine containing ligands were synthesized. The three ligands differ from each other in the substitution of the pyridine pendant arm, namely they have a carboxylic acid, an ethylamide, or an ethyl ester substituent, i.e., these ligands are 6,6′,6″-[1,4,7-triazacyclononane-1,4,7-triyltris(methylene)]tris[pyridine-2-carboxylic acid] (H3tpatcn), -tris[pyridine-2-carboxamide] (tpatcnam), and -tris[pyridine-2-carboxylic acid] triethyl ester (tpatcnes) respectively. The quantum yields of both the europium(III) and terbium(III) emission, upon ligand excitation, were highly dependent upon ligand substitution, with a ca. 50-fold decrease for the carboxamide derivative in comparison to the picolinic acid (=pyridine-2-carboxylic acid) based ligand. Detailed analysis of the radiative rate constants and the energy of the triplet states for the three ligand systems revealed a less efficient energy transfer for the carboxamide-based systems. The stability of the three ligand systems in H2O was investigated. Although hydrolysis of the ethyl ester occurred in H2O for the [Ln(tpatcnes)](OTf)3 complexes, the tripositive [Ln(tpatcnam)](OTf)3 complexes and the neutral [Ln(tpatcn)] complexes showed high stability in H2O which makes them suitable for application in biological media. The [Tb(tpatcn)] complex formed easily in H2O and was thermodynamically stable at physiological pH (pTb 14.9), whereas the [Ln(tpatcnam)](OTf)3 complexes showed a very high kinetic stability in H2O, and once prepared in organic solvents, remained undissociated in H2O.
000203038 700__ $$aNocton, Gregory
000203038 700__ $$aNonat, Aline
000203038 700__ $$aGateau, Christelle
000203038 700__ $$0248440$$aMazzanti, Marinella$$g166619
000203038 773__ $$j92$$k11$$q2257-2273$$tHelvetica Chimica Acta
000203038 909C0 $$0252515$$pGCC$$xU12966
000203038 909CO $$ooai:infoscience.tind.io:203038$$pSB$$particle
000203038 917Z8 $$x148230
000203038 937__ $$aEPFL-ARTICLE-203038
000203038 973__ $$aOTHER$$rREVIEWED$$sPUBLISHED
000203038 980__ $$aARTICLE