城谷 大

This paper concerns with the synthesis and the luminescence spectra of lanthanide complexes of EuIII) and/or Eu(II) or Tb(III) ions which are embedded into fibrous palygorskite and sepiolite clays in which the magnesium ion are ion exchanged with lanthanide ions. The He-Cd laser excitation photoluminescence of the present complexes without organic ligands exhibit the deferration effects. The phosphors with light harvesting ligands such as benzophenone derivatives and 1,10-phenanthroline give the fairly strong visible luminescence by UV-A light excitation with a LED black light in a light room under fluorescent lamps. Further, the temperature dependent phosphors with benzophenone derivatives exhibit the stronger luminescence with increasing the temperature over 100 degrees C.

The preparation of tetrakis((+)-hfbc) lanthanide(III) complexes with an encapsulated alkali metal and ammonium ions M[Ln((+)-hfbc)4] (hereafter abbreviated as M-Ln?:?(+)-hfbc, (+)-heptafluorobutyrylcamphorate; M, ammonium or benzyl ammonium ions as well as alkali metal ions) was reported and discussed. The electronic circular dichroism (CD) spectra in the intraligand p-p* transition of MLn were examined in view of the solvent effect. Here, the concentration, alkali metal, and ammonium ion dependences are compared with the solid CD, 5D0???7F0(Eu(III)) excitation spectra, circularly polarized luminescence, and vibrational circular dichroism. It has been revealed that the dodecahedral eight coordinate DD-8-M-Ln complexes in crystals are equilibrated between the diastereoselectively formed square antiprism eight coordinate SAPR-8-M-Ln and [Ln((+)-hfbc)3] in EtOH and CH3CN solutions or between the SAPR-8-M-Ln and DD-D2d(mmmm)-8-M-Ln complexes in CHCl3 solution. The observed CD couplets are found to reflect the exciton CD couplets which are useful to determine the four-bladed SAPR-(llll) absolute configuration around the lanthanide(III) ion. Chirality 24:10551062, 2012. (c) 2012 Wiley Periodicals, Inc.

For electronic circular dichroism in the 4f-4f transitions (4f-4f CD) of a series of nine tetrakis ((+)-3-heptafluorobutyrylcamphorato) Ln(III) complexes,Delta-SAPR-8-C-4(llll) Cs[Ln((+)-hfbc)(4)]center dot H2O (Cs-Ln = Cs-Pr, -Nd, -Sm, -Eu, -Dy, -Ho, -Er, -Tm, -Yb), the spectroscopic observables such as the dissymmetry factor g = Delta epsilon/epsilon values with the intensities (Delta epsilon) of the CD components and the molar absorption intensities (epsilon) in the 4f-4f transitions between the L-2S+1(J) levels are compared with each other to test the classification of the CD components in the relative order of the observables predicted in terms of the selection rule for 4f-4f transitions. The 4f-4f CD-based chiroptical spectra-structural relationship across the series of Delta-SAPR-8-C-4(llll) lanthanide(III) complexes is proposed: the signs of the 4f-4f CD or CPL in the hypersensitive transitions are related to the absolute configuration; Ln complexes with a negative CD component have the Delta-configuration around Ln(III) and vice versa.

The luminescence and circularly polarized luminescence (CPL) spectra of M-I[Eu((+)-hfbc)(4)] show a similar behavior to the exciton CD in the intraligand pi-pi* transitions when the alkali metal ions and solvents are manipulated. There is a difference in susceptibility in solvation toward the alkali metal ions but not toward the Eu(III) ion, as in the case of axially symmetric DOTA-type compounds. The remarkable CPL in the 4f-4f transitions provide much more information on the stereospecific formation of chiral Eu(111) complexes, since CPL spectroscopy is limited to luminescent species and reflects selectively toward helicity of the local structural environment around the lanthanide(III). While in comparison, exciton CD reveals the chiral structural information from the helical arrangement of the four bladed chelates. Of special importance, the observation of the highest CPL activities measured to date for lanthanide(III)-containing compounds (i.e., Eu and Sm) in solution supports the theory that the chirality of lanthanide(III) in the excited state corresponds to that in the ground state, which was derived from the exciton CD.

The vibrational circular dichroism (VCD) spectra for Delta-M[Ln((+)-hfbC)(4)] (M(I) = Na, K, Rb, Cs; Ln(III) = La, tu; abbreviated as M-Ln) and Delta-Cs[Yb((+)-hfbC)(4)] (Cs-Yb) were observed in CDCl(3) solutions. The VCD signs and/or intensities are mostly different from those of the Delta-tris(beta-diketonato) transition-metal complexes. The M-Ln complexes give the strong VCD peak(s) near 1550 cm(-1). These VCD patterns are different from each lanthanide(III) complex, but their intensities change with variation of the alkali metal ion. A positive-negative couplet VCD near 1550 cm(-1) for the Delta-M-La complexes is observed similarly for the Delta-tris(beta-diketonato) complexes, confirming the assignment to the Delta absolute configuration based on the exciton CD. The density functional theory calculated VCD for the two peaks at 1650 and 1550 cm(-1) reproduces the relative intensity and signs of the observed ones for the Delta center dot M-La(III) complexes.

The largest CPL activity ever measured was observed for cesium tetrakis(3-heptafluoro-butylryl-(+)-camphorato) Eu(III) complexes in EtOH and CHCl3 solutions substantiating the stereospecific formation of chiral Delta-SAPR-(C-4) configuration with the aid of Cs+ center dot center dot center dot FC (fluorocarbon) interactions more clearly than the exciton CD spectra.

The X-ray crystal structure of tetrakis (+)-hfbc Pr(III) complex, Na[Pr((+)-hfbc)(4)]center dot CH3CN, was compared with that of the corresponding Na-La complex with a pseudo-achiral dodecahedron, and the solution CD spectra were also discussed in the 4f-4f transition in consideration of the exciton CD couplet showing Delta-SAPR-8 configuration in CHCl3. (c) 2007 Published by Elsevier B.V.

For newly prepared sodium tetrakis( 3-heptafluorobutylryl-( +)-camphorato) Ln( III) complexes, the X-ray crystal analysis revealed an unprecedented pseudo-achiral dodecahedron ( DD-8 ( D-2d)), whereas in CHCl3 solution, the exciton CD and F-19 NMR spectra showed a novel chiral Delta-SAPR-8 ( C-4) configuration which is stereospecifically formed by a trapped Na+ ion with Na+center dot center dot center dot FC ( fluorocarbon) interactions.

This study demonstrates the first observation of energy transfer from the doublet state of the nitronyl nitroxide radical ligand in Ln(III) complexes, exerting the light-harvesting antenna effect on the NIR luminescence for the first time. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)