26 research outputs found
Eu(III) Chiral Coordination Polymer with a Structural Transformation System
A luminescent EuÂ(III)
chiral coordination polymer with a structural transformation system,
[EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> (hfa: haxafluoroacetylacetonato, (<i>R</i>)-bidp:
(<i>R</i>)-1,1â˛-binaphthyl-2,2â˛-bisÂ(diphenylphosphinate),
is reported. Single-crystal X-ray analysis revealed a characteristic
helical polymer structure of [EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> with hydrogenâfluorine/Ď
interactions. [EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> shows high thermostability (decomposition
temperature = 320 °C) and strong luminescence properties (the
4fâ4f emission quantum yield = 76%) in the solid state due
to its tight packing and asymmetric structure. [EuÂ(hfa)<sub>3</sub>((R)-bidp)]<sub><i>n</i></sub> is also transformed from
a polymer to monomer structure in liquid media. The chiroptical properties
of the monomer form in liquid media were characterized by using circular
dichroism and circularly polarized luminescence spectra. In this study,
structural and photophysical properties of a luminescent EuÂ(III) chiral
coordination polymer with a structural transformation system were
demonstrated
Eu(III) Chiral Coordination Polymer with a Structural Transformation System
A luminescent EuÂ(III)
chiral coordination polymer with a structural transformation system,
[EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> (hfa: haxafluoroacetylacetonato, (<i>R</i>)-bidp:
(<i>R</i>)-1,1â˛-binaphthyl-2,2â˛-bisÂ(diphenylphosphinate),
is reported. Single-crystal X-ray analysis revealed a characteristic
helical polymer structure of [EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> with hydrogenâfluorine/Ď
interactions. [EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> shows high thermostability (decomposition
temperature = 320 °C) and strong luminescence properties (the
4fâ4f emission quantum yield = 76%) in the solid state due
to its tight packing and asymmetric structure. [EuÂ(hfa)<sub>3</sub>((R)-bidp)]<sub><i>n</i></sub> is also transformed from
a polymer to monomer structure in liquid media. The chiroptical properties
of the monomer form in liquid media were characterized by using circular
dichroism and circularly polarized luminescence spectra. In this study,
structural and photophysical properties of a luminescent EuÂ(III) chiral
coordination polymer with a structural transformation system were
demonstrated
Eu(III) Chiral Coordination Polymer with a Structural Transformation System
A luminescent EuÂ(III)
chiral coordination polymer with a structural transformation system,
[EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> (hfa: haxafluoroacetylacetonato, (<i>R</i>)-bidp:
(<i>R</i>)-1,1â˛-binaphthyl-2,2â˛-bisÂ(diphenylphosphinate),
is reported. Single-crystal X-ray analysis revealed a characteristic
helical polymer structure of [EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> with hydrogenâfluorine/Ď
interactions. [EuÂ(hfa)<sub>3</sub>((<i>R</i>)-bidp)]<sub><i>n</i></sub> shows high thermostability (decomposition
temperature = 320 °C) and strong luminescence properties (the
4fâ4f emission quantum yield = 76%) in the solid state due
to its tight packing and asymmetric structure. [EuÂ(hfa)<sub>3</sub>((R)-bidp)]<sub><i>n</i></sub> is also transformed from
a polymer to monomer structure in liquid media. The chiroptical properties
of the monomer form in liquid media were characterized by using circular
dichroism and circularly polarized luminescence spectra. In this study,
structural and photophysical properties of a luminescent EuÂ(III) chiral
coordination polymer with a structural transformation system were
demonstrated
JâType Heteroexciton Coupling Effect on an Asymmetric DonorâAcceptorâDonor-Type Fluorophore
The
novel donorâacceptorâdonor (DâAâD)-type
fluorophore with an asymmetric structure is reported. The twisted-induced
charge transfer (TICT) luminescence was observed. The degree of charge
transfer and radiative rate constant in the luminescence increased
simultaneously with increase in orientational polarizability of solvents.
In contrast to the numerous CT fluorophore researches, this behavior
has never been previously observed. This characteristic behavior reveals
the existence of an effective exciton coupling between the CT states
in the donorâacceptorâdonor-type fluorophore for the
first time
Nona-Coordinated Chiral Eu(III) Complexes with Stereoselective LigandâLigand Noncovalent Interactions for Enhanced Circularly Polarized Luminescence
Circularly polarized luminescence (CPL) of chiral EuÂ(III)
complexes
with nona- and octa-coordinated structures, [EuÂ(<i>R</i>/<i>S</i>-iPr-Pybox)Â(<i>D</i>-facam)<sub>3</sub>] (<b>1-</b><i><b>R</b></i>/<b>1-</b><i><b>S</b></i>; <i>R</i>/<i>S</i>-iPr-Pybox, 2,6-bisÂ(4<i>R</i>/4<i>S</i>-isopropyl-2-oxazolin-2-yl)Âpyridine; <i>D</i>-facam, 3-trifluoroacetyl-<i>d</i>-camphor),
[EuÂ(<i>S</i>,<i>S</i>-Me-Ph-Pybox)Â(<i>D</i>-facam)<sub>3</sub>] (<b>2-</b><i><b>SS</b></i>; <i>S</i>,<i>S</i>-Me-Ph-Pybox, 2,6-bisÂ(4<i>S</i>-methyl-5<i>S</i>-phenyl-2-oxazolin-2-yl)Âpyridine),
and [EuÂ(Phen)Â(<i>D</i>-facam)<sub>3</sub>] (<b>3</b>; Phen, 1,10-phenanthroline) are reported, and their structural features
are discussed on the basis of X-ray crystallographic analyses. These
chiral EuÂ(III) complexes showed relatively intense photoluminescence
due to their <sup>5</sup>D<sub>0</sub> â <sup>7</sup>F<sub>1</sub> (magnetic-dipole) and <sup>5</sup>D<sub>0</sub> â <sup>7</sup>F<sub>2</sub> (electric-dipole) transition. The dissymmetry
factors of CPL (<i>g</i><sub>CPL</sub>) at the former band
of <b>1-</b><i><b>R</b></i> and <b>1-</b><i><b>S</b></i> were as large as â1.0 and
â0.8, respectively, while the <i>g</i><sub>CPL</sub> of <b>3</b> at the <sup>5</sup>D<sub>0</sub> â <sup>7</sup>F<sub>1</sub> transition was relatively small (<i>g</i><sub>CPL</sub> = â0.46). X-ray crystallographic data indicated
specific ligandâligand hydrogen bonding in these compounds
which was expected to stabilize their chiral structures even in solution
phase. CPL properties of <b>1-</b><i><b>R</b></i> and <b>1-</b><i><b>S</b></i> were discussed
in terms of transition nature of lanthanide luminescence
Nona-Coordinated Chiral Eu(III) Complexes with Stereoselective LigandâLigand Noncovalent Interactions for Enhanced Circularly Polarized Luminescence
Circularly polarized luminescence (CPL) of chiral EuÂ(III)
complexes
with nona- and octa-coordinated structures, [EuÂ(<i>R</i>/<i>S</i>-iPr-Pybox)Â(<i>D</i>-facam)<sub>3</sub>] (<b>1-</b><i><b>R</b></i>/<b>1-</b><i><b>S</b></i>; <i>R</i>/<i>S</i>-iPr-Pybox, 2,6-bisÂ(4<i>R</i>/4<i>S</i>-isopropyl-2-oxazolin-2-yl)Âpyridine; <i>D</i>-facam, 3-trifluoroacetyl-<i>d</i>-camphor),
[EuÂ(<i>S</i>,<i>S</i>-Me-Ph-Pybox)Â(<i>D</i>-facam)<sub>3</sub>] (<b>2-</b><i><b>SS</b></i>; <i>S</i>,<i>S</i>-Me-Ph-Pybox, 2,6-bisÂ(4<i>S</i>-methyl-5<i>S</i>-phenyl-2-oxazolin-2-yl)Âpyridine),
and [EuÂ(Phen)Â(<i>D</i>-facam)<sub>3</sub>] (<b>3</b>; Phen, 1,10-phenanthroline) are reported, and their structural features
are discussed on the basis of X-ray crystallographic analyses. These
chiral EuÂ(III) complexes showed relatively intense photoluminescence
due to their <sup>5</sup>D<sub>0</sub> â <sup>7</sup>F<sub>1</sub> (magnetic-dipole) and <sup>5</sup>D<sub>0</sub> â <sup>7</sup>F<sub>2</sub> (electric-dipole) transition. The dissymmetry
factors of CPL (<i>g</i><sub>CPL</sub>) at the former band
of <b>1-</b><i><b>R</b></i> and <b>1-</b><i><b>S</b></i> were as large as â1.0 and
â0.8, respectively, while the <i>g</i><sub>CPL</sub> of <b>3</b> at the <sup>5</sup>D<sub>0</sub> â <sup>7</sup>F<sub>1</sub> transition was relatively small (<i>g</i><sub>CPL</sub> = â0.46). X-ray crystallographic data indicated
specific ligandâligand hydrogen bonding in these compounds
which was expected to stabilize their chiral structures even in solution
phase. CPL properties of <b>1-</b><i><b>R</b></i> and <b>1-</b><i><b>S</b></i> were discussed
in terms of transition nature of lanthanide luminescence
Sandglass-Typed Single Chameleon Luminophore for Water Mapping Measurements: Intramolecular Energy Migrations in the Hydrophilic Tb(III)/Sm(III) Cluster
Novel hydrophilic and color-changeable single chameleon
luminophores
composed of Tb(III)/Sm(III) nona-nuclear clusters [TbxSm9âx(Sal-PEG-n)16(Îź-OH)10]+(NO3)â (x = 1, 2, 3, and 9;
Sal-PEG-n: salicylate polyethylene glycolmethylester, n = 2 and 4) are reported for water mapping measurements.
Their characteristic sandglass structures and aggregates were analyzed
using X-ray single crystal analysis and dynamic light scattering (DLS)
measurements. The green- and yellow-luminescence of [Tb3Sm6(Sal-PEG-4)16(Îź-OH)]+(NO3)â in water were observed at 20 and 50 °C,
respectively. The ratio-metric luminescence analysis using green Tb(III)
and orange Sm(III) emission bands is a promising candidate for exact
temperature distribution measurements in fluid dynamics. The effective
temperature-sensing property based on the competitive intramolecular
energy transfer processes between Tb(III)-to-ligand and Tb(III)-to-Sm(III)
in a non-a-nuclear cluster is explained using temperature-dependent
kinetic analyses in the excited state
First Synthesis of EuS Nanoparticle Thin Film with a Wide Energy Gap and Giant Magneto-Optical Efficiency on a Glass Electrode
Novel magneto-optical thin films composed of europium
sulfide (EuS)
nanoparticles on a glass electrode exhibit large magneto-optical efficiency
and a wide energy gap. EuS nanoparticle thin films are prepared by
the electrochemical reduction of a single-source precursor, a EuÂ(III)
dithiocarbamate complex (tetraphenylphosphonum tetrakisÂ(diethyldithiocarbamate)
europiumÂ(III)). The EuS nanoparticle thin films were prepared on indiumâtin
oxide (ITO)-coated glass electrodes and characterized by electrochemical
analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy,
transmission electron microscopy, laser scanning microscopy, and absorption
spectroscopy. Faraday rotation spectra for estimation of the magneto-optical
efficiency have clear positive and negative peaks, which are attributed
to the 4fâ5d transitions of the EuS thin films. The positive
and negative peaks of the Faraday rotation spectrum are 525 and 680
nm, which are directly related to the energy gap of the EuS nanoparticle
thin film (2.4 eV). That spectrum indicates that the EuS nanoparticle
thin films are blue shifted in comparison with 7 nm diameter EuS nanoparticles
(2.2 eV). The Verdet constant of the thin film was 11 mdeg/cm Oe at
525 nm, which is approximately 10 times larger than that of previously
reported EuS nanoparticles
Red Luminescent Eu(III) Coordination Bricks Excited on Blue LED Chip
Three types of red
luminescent EuÂ(III) complexes with Schiff base and hfa ligands (hfa:
hexafluoroacetylacetonate), mononuclear [EuÂ(hfa)<sub>2</sub>(OAc)Â(salen)<sub>2</sub>] (OAc: acetate anion, salen: <i>N,N</i>â˛-bisÂ(salicylidene)Âethylenediamine),
brick-type [Eu<sub>2</sub>(hfa)<sub>4</sub>(OAc)<sub>2</sub>(salbn)<sub>2</sub>] (salbn: <i>N,N</i>â˛-bisÂ(salicylidene)-1,4-butanediamine),
and polynuclear [EuÂ(hfa)<sub>2</sub>(OAc)Â(salhen)]<sub><i>n</i></sub> (salhen: <i>N,N</i>â˛-bisÂ(salicylidene)-1,6-hexanediamine)
are reported for white light-emitting diode (LED) devices. Among these
complexes, brick-type [Eu<sub>2</sub>(hfa)<sub>4</sub>(OAc)<sub>2</sub>(salbn)<sub>2</sub>] excited by blue light (460 nm) exhibits the
photosensitized quantum yield (ÎŚ<sub>ĎâĎ*</sub> = 47%) and remarkably high efficiency of sensitization (Ρ<sub>sens</sub> = 96%). The efficiency of sensitization is caused by the
excited state based on ligandâligand interaction between the
Schiff base and hfa ligands in EuÂ(III) complexes. To fabricate LED
devices, the red luminescent [Eu<sub>2</sub>(hfa)<sub>4</sub>(OAc)<sub>2</sub>(salbn)<sub>2</sub>] was mounted on an InGaN blue LED chip
Synthesis, Optical Properties, and Crystal Structures of Dithienostannoles
Reactions of dichlorodiphenylstannane
with 3,3â˛-dilithio-5,5â˛-bisÂ(trimethylsilyl)-2,2â˛-bithiophene
and 3,3â˛-dilithio-2,2â˛-diÂ(benzoÂ[<i>b</i>]Âthiophene)
gave 1,1-diphenyl-3,6-bisÂ(trimethylsilyl)Âdithienostannole (<b>DTSn1</b>) and diÂ(benzoÂ[<i>b</i>]Âthieno)-1,1-diphenylstannole (<b>DTSn2</b>), respectively. Optical properties of the dithienostannoles
and the results of DFT calculations on a model suggested an in-phase
interaction between Sn Ď* and bithiophene Ď* orbitals,
stabilizing the LUMO. Interestingly, <b>DTSn1</b> showed crystallization-enhanced
emission and the photoluminescence (PL) quantum yield of the crystals
was determined to be higher by about 20 times than that in the amorphous
and solution phase, while <b>DTSn2</b> exhibited moderate PL
efficiency both as crystals and in solution. Crystal structures of
the dithienostannoles were determined by X-ray diffraction studies,
which showed the differences in the molecular packing between <b>DTSn1</b> and <b>DTSn2</b>, being responsible for their
different PL properties in the crystal state