Eu(III) Chiral Coordination Polymer with a Structural Transformation System

A luminescent Eu­(III) chiral coordination polymer with a structural transformation system, [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> (hfa: haxafluoroacetylacetonato, (<i>R</i>)-bidp: (<i>R</i>)-1,1′-binaphthyl-2,2′-bis­(diphenylphosphinate), is reported. Single-crystal X-ray analysis revealed a characteristic helical polymer structure of [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> with hydrogen–fluorine/π interactions. [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> shows high thermostability (decomposition temperature = 320 °C) and strong luminescence properties (the 4f–4f emission quantum yield = 76%) in the solid state due to its tight packing and asymmetric structure. [Eu­(hfa)₃((R)-bidp)]_<i>n</i> 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 Eu­(III) chiral coordination polymer with a structural transformation system were demonstrated

Eu(III) Chiral Coordination Polymer with a Structural Transformation System

A luminescent Eu­(III) chiral coordination polymer with a structural transformation system, [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> (hfa: haxafluoroacetylacetonato, (<i>R</i>)-bidp: (<i>R</i>)-1,1′-binaphthyl-2,2′-bis­(diphenylphosphinate), is reported. Single-crystal X-ray analysis revealed a characteristic helical polymer structure of [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> with hydrogen–fluorine/π interactions. [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> shows high thermostability (decomposition temperature = 320 °C) and strong luminescence properties (the 4f–4f emission quantum yield = 76%) in the solid state due to its tight packing and asymmetric structure. [Eu­(hfa)₃((R)-bidp)]_<i>n</i> 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 Eu­(III) chiral coordination polymer with a structural transformation system were demonstrated

Eu(III) Chiral Coordination Polymer with a Structural Transformation System

A luminescent Eu­(III) chiral coordination polymer with a structural transformation system, [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> (hfa: haxafluoroacetylacetonato, (<i>R</i>)-bidp: (<i>R</i>)-1,1′-binaphthyl-2,2′-bis­(diphenylphosphinate), is reported. Single-crystal X-ray analysis revealed a characteristic helical polymer structure of [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> with hydrogen–fluorine/π interactions. [Eu­(hfa)₃((<i>R</i>)-bidp)]_<i>n</i> shows high thermostability (decomposition temperature = 320 °C) and strong luminescence properties (the 4f–4f emission quantum yield = 76%) in the solid state due to its tight packing and asymmetric structure. [Eu­(hfa)₃((R)-bidp)]_<i>n</i> 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 Eu­(III) chiral coordination polymer with a structural transformation system were demonstrated

J‑Type Heteroexciton Coupling Effect on an Asymmetric Donor–Acceptor–Donor-Type Fluorophore

The novel donor–acceptor–donor (D–A–D)-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 donor–acceptor–donor-type fluorophore for the first time

Nona-Coordinated Chiral Eu(III) Complexes with Stereoselective Ligand–Ligand Noncovalent Interactions for Enhanced Circularly Polarized Luminescence

Circularly polarized luminescence (CPL) of chiral Eu­(III) complexes with nona- and octa-coordinated structures, [Eu­(<i>R</i>/<i>S</i>-iPr-Pybox)­(<i>D</i>-facam)₃] (<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-bis­(4<i>R</i>/4<i>S</i>-isopropyl-2-oxazolin-2-yl)­pyridine; <i>D</i>-facam, 3-trifluoroacetyl-<i>d</i>-camphor), [Eu­(<i>S</i>,<i>S</i>-Me-Ph-Pybox)­(<i>D</i>-facam)₃] (<b>2-</b><i><b>SS</b></i>; <i>S</i>,<i>S</i>-Me-Ph-Pybox, 2,6-bis­(4<i>S</i>-methyl-5<i>S</i>-phenyl-2-oxazolin-2-yl)­pyridine), and [Eu­(Phen)­(<i>D</i>-facam)₃] (<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 Eu­(III) complexes showed relatively intense photoluminescence due to their ⁵D₀ → ⁷F₁ (magnetic-dipole) and ⁵D₀ → ⁷F₂ (electric-dipole) transition. The dissymmetry factors of CPL (<i>g</i>_CPL) 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 −1.0 and −0.8, respectively, while the <i>g</i>_CPL of <b>3</b> at the ⁵D₀ → ⁷F₁ transition was relatively small (<i>g</i>_CPL = −0.46). X-ray crystallographic data indicated specific ligand–ligand 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 Ligand–Ligand Noncovalent Interactions for Enhanced Circularly Polarized Luminescence

Circularly polarized luminescence (CPL) of chiral Eu­(III) complexes with nona- and octa-coordinated structures, [Eu­(<i>R</i>/<i>S</i>-iPr-Pybox)­(<i>D</i>-facam)₃] (<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-bis­(4<i>R</i>/4<i>S</i>-isopropyl-2-oxazolin-2-yl)­pyridine; <i>D</i>-facam, 3-trifluoroacetyl-<i>d</i>-camphor), [Eu­(<i>S</i>,<i>S</i>-Me-Ph-Pybox)­(<i>D</i>-facam)₃] (<b>2-</b><i><b>SS</b></i>; <i>S</i>,<i>S</i>-Me-Ph-Pybox, 2,6-bis­(4<i>S</i>-methyl-5<i>S</i>-phenyl-2-oxazolin-2-yl)­pyridine), and [Eu­(Phen)­(<i>D</i>-facam)₃] (<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 Eu­(III) complexes showed relatively intense photoluminescence due to their ⁵D₀ → ⁷F₁ (magnetic-dipole) and ⁵D₀ → ⁷F₂ (electric-dipole) transition. The dissymmetry factors of CPL (<i>g</i>_CPL) 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 −1.0 and −0.8, respectively, while the <i>g</i>_CPL of <b>3</b> at the ⁵D₀ → ⁷F₁ transition was relatively small (<i>g</i>_CPL = −0.46). X-ray crystallographic data indicated specific ligand–ligand 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 [TbxSm9–x(Sal-PEG-n)16(μ-OH)10]+(NO3)− (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(μ-OH)]+(NO3)− 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 Eu­(III) dithiocarbamate complex (tetraphenylphosphonum tetrakis­(diethyldithiocarbamate) europium­(III)). The EuS nanoparticle thin films were prepared on indium–tin 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 4f–5d 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 Eu­(III) complexes with Schiff base and hfa ligands (hfa: hexafluoroacetylacetonate), mononuclear [Eu­(hfa)₂(OAc)­(salen)₂] (OAc: acetate anion, salen: <i>N,N</i>′-bis­(salicylidene)­ethylenediamine), brick-type [Eu₂(hfa)₄(OAc)₂(salbn)₂] (salbn: <i>N,N</i>′-bis­(salicylidene)-1,4-butanediamine), and polynuclear [Eu­(hfa)₂(OAc)­(salhen)]_<i>n</i> (salhen: <i>N,N</i>′-bis­(salicylidene)-1,6-hexanediamine) are reported for white light-emitting diode (LED) devices. Among these complexes, brick-type [Eu₂(hfa)₄(OAc)₂(salbn)₂] excited by blue light (460 nm) exhibits the photosensitized quantum yield (Φ_π–π* = 47%) and remarkably high efficiency of sensitization (η_sens = 96%). The efficiency of sensitization is caused by the excited state based on ligand–ligand interaction between the Schiff base and hfa ligands in Eu­(III) complexes. To fabricate LED devices, the red luminescent [Eu₂(hfa)₄(OAc)₂(salbn)₂] was mounted on an InGaN blue LED chip

Synthesis, Optical Properties, and Crystal Structures of Dithienostannoles

Reactions of dichlorodiphenylstannane with 3,3′-dilithio-5,5′-bis­(trimethylsilyl)-2,2′-bithiophene and 3,3′-dilithio-2,2′-di­(benzo­[<i>b</i>]­thiophene) gave 1,1-diphenyl-3,6-bis­(trimethylsilyl)­dithienostannole (<b>DTSn1</b>) and di­(benzo­[<i>b</i>]­thieno)-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 σ* and bithiophene π* 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