Preparation And Luminescent Properties Of Rare Earth Complexes With Visible Photosensitized Aromatic Carboxylic Acid

Near-infrared lanthanide materials have the following features, such as characteristic sharp luminescence, a large Stoke’s shift, good photostability and low toxicity. Particularly, lanthanide complexes can improve luminescence of lanthanide ions because organic ligands transfer the energy. They have many reports from the very early research, however their excitation wavelength are generally in the ultraviolet-light region. As we know, the visible-light is less harmful to biological tissue than ultraviolet-light in luminescent probes and biological media. Lanthanide complexes N3-Ln(â…¢)(Ln=Nd, Yb, Er, Ho) and Nd (L)3·2H2O (L=TPA-1, TPA-2, TPA-3) based on visible-light sensitization were synthesized with N3, TPA-1, TPA-2and TPA-3, and their luminescent properties were researched.1. N3was synthesized with2,2’-bipyridine-4,4’-acid, ruthenium trichloride and sodium thiocyanate by complexation and substitution reaction and its structure was characterized by IR,1H NMR and MS, the yield of N3was46.9%and the purity was99.0%(HPLC). Four lanthanide complexes N3-Ln(â…¢)(Ln=Nd, Yb, Er, Ho) were synthesized with N3, and their structures were characterized by IR and UV-Vis-NIR absorption spectra. Furthermore, their thermal properties along with florescence emission characters were investigated. The results showed that every complex contained coordination water molecules and molecular skeleton of the complexes were broken when temperature was308℃. Absorption of all complexes were improved due to N3was introduced. N3-Nd(â…¢) and N3-Yb(â…¢) showed the characteristic emission bands of lanthanide ions in the near-infrared region, when excitation wavelength was468nm. However Er3+and Ho3+-based luminescence had not been obtained, It could be explained that the suitability of the energy gap between triplet level of ligand and energy level of Er3+and Ho3+was weak.2. TPA-1, TPA-2and TPA-3were synthesized by Vilsmeier, Suzuki-Miyaura, Wittig and Knoevenagel reaction and their structures were characterized by IR,1H NMR and MS. Three lanthanide complexes Nd (L)3·2H2O (L=TPA-1, TPA-2, TPA-3) were synthesized with TPA-1, TPA-2and TPA-3and their structures were characterized by element analysis,1H NMR and infrared spectra. Furthermore, the effects of the length of conjugated chain on absorption and luminescence properties were investigated by UV-visible absorption and fluorescence spectra. The results showed that three complexes contained two water molecules. The molar absorption coefficient and absorbance range of complexes had been remarkably improved by prolong the conjugated chains. Meanwhile Nd (TPA-1)3·2H2O and Nd (TPA-2)3·2H2O showed three emission bands of at889,1063and1339nm which should be assigned to4F3/2â†'-4I9/2,4F3/2â†'4I11/2and4F3/2â†'4I13/2transitions of the Nd3+.