Abstracts

Since some of the scarce molecular-based Er-centered emitters reported in the literature are based on [ErN₃O₆] and [ErN₉] coordination geometry, we explored the optical properties of two Er^III complexes, containing a hexaazamacrocyclic ligand with two- (1) or three-carbon (2) aliphatic lateral spacers, and three auxiliary isothiocyanate ligands. Luminescent properties were evaluated using ligand- and metal-centered excitation. Bluish-green and green emissions of the Er^III ion were detected upon ligand-centered excitation, demonstrating that these macrocycles act as antenna to sensitize the erbium(III) luminescence. Energy transfer mechanisms and temperature-dependent luminescence were analyzed. Besides the excitation in the ligands (Vis), the erbium-centered excitation at 980 nm (NIR) allowed the detection, in both cases, of bluish-green, green, and red up-converted emissions, and also the downshifted NIR emission. The possible mechanisms of these transitions are described and analyzed. Therefore, Vis-to-Vis (via ligand excitation), NIR-to-Vis and NIR-to-NIR emitters (upon 980 nm excitation) were achieved with these molecular systems.