Absorption- and Excitation-Modulated Luminescence of Pr, Nd, and Lu Compounds with Dianions of Tetrafluoroterephthalic and Camphoric Acids.

Abstract

The luminescence of coordination polymers of Pr, Nd, and Lu with tetrafluoroterephthalate and camphorate, [Ln(Fbdc)(DMF)(HO)] (Ln = Pr, Nd, Lu) and [Ln(Camph)(NO)(MeOH)] (Ln = Pr, Nd, Lu), was studied. Ligand-centered and/or metal-centered emissions appear, which depend on the excitation wavelength, ultimately allowing the emitted light color to be adjusted. Low-efficiency ligand-to-metal energy transfer leads to a difference between the excitation spectra of the tetrafluoroterephthalate- and camphorate-Pr compounds, arising from a primary filtering effect on the ligand-centered excitation, by Pr absorption. A secondary inner filter effect significantly changes the shape of the luminescence band, allowing a wide variation in the emission color, producing, for instance, a purple color, which is not the normal spectral emission. The low-efficiency energy transfer renders tetrafluoroterephthalate and camphorate ineffective as traditional "antenna" ligands for Pr and Nd.