Mitsunori Iwamuro

Observation of neodymium electroluminescence

Organic electroluminescence devices using a neodymium(III) complex as an emitting layer were fabricated. The cell structure of glass substrate/indium–tin–oxide/N,N′-diphenyl-N,N′-di(m-tolyl)-benzidine/tris(dibenzoylmethanato)(monobathophenanthroline)neodymium(III) complex/tris(8-quinolinolato)aluminum(III) complex/Mg:Ag was employed. Sharp near-infrared emission bands assigned to f–f transitions of neodymium ion were obtained at dc bias voltage of over 15 V.

Luminescence of Nd3+ complexes with some asymmetric ligands in organic solutions

Abstract A novel Nd3+ complex, Nd(POA-D)3, with asymmetric ligands (POA: perfluorooctanoylacetic acid), was synthesized in order to enhance the transition probability in its f–f transition by reducing symmetry of the ligand field around Nd3+. This complex gives the 2.5 times higher oscillator strength of the hypersensitive transition in methanol-d4 than the corresponding symmetrical complex, Nd(POM-D)3 (POM: bisperfluorooctanoylmethane). The Stark splitting of the emitting level of Nd(POA-D)3 was observed and the Judd-Ofelt analysis gave a large Ω2 value, clearly showing the asymmetric environment around Nd3+. 13C NMR analysis, molecular orbital and molecular mechanics calculations and EXAFS analysis suggest that the asymmetric environment achieved in Nd(POA-D)3 is ascribed mainly to the asymmetric distribution of electrons on the coordinating O atoms. The higher absorption coefficient of Nd(POA-D)3 leads to 1.86 times stronger emission than Nd(POM-D)3 when measured at the common concentration and conditions. It is stressed that introduction of asymmetric ligands is a promising way for promoting emission of Nd3+ in solutions when coupled with replacement of C–H bonds with C–D and C–F in the ligands.

Photosensitized luminescence of novel β-diketonato Nd(III) complexes in solution

Photosensitized luminescence in the near-infrared region of five low vibrational β–diketonato neodymium(III) complexes, tris(1,1,1,5,5,5-hexafluoroacetylacetonato)neodymium(III) (1), tris(4,4,5,5,5-pentafluoro-1-pentafluorophenyl-1,3-pentanedionato)neodymium(III) (2), tris(4,4,5,5,6,6,6-heptafluoro-1-pentafluorophenyl-1,3-hexanedionato)neodymium(III) (3), tris(4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-pentadecafluoro-1-pentafluorophenyl-1,3-decanedionato)neodymium(III) (4), and tris[bis(pentafluorobenzoyl)methanato]neodymium(III) (5), were examined by the selective excitation of the ligand moieties in THF-d8. The intramolecular energy transfer efficiencies from the excited ligands to the central Nd(III) ion were determined and the order of 1<2<3<4<5 was obtained. The order of the overlap area between the phosphorescence due to the ligand moieties and the absorption due to Nd(III) in the 400–650 nm spectral region was also increased in the above order. These results suggest that the energy matching of the donor and the acceptor is decisive for the efficient photosensitized luminescence of Nd(III) complexes.