Guest-Responsive Near-Infrared-Luminescent Metal-Organic Cage Organized by Porphyrin Dyes and Yb(III) Complexes.

Metal-organic cages (MOCs) with luminophores have significant advantages for the facile detection of specific molecules based on turn-on or turn-off luminescence changes induced by host-guest complexation. One important challenge is the development of turn-on-type near-infrared (NIR)-luminescent MOCs. In this study, we synthesized a novel MOC consisting of two porphyrin dyes linked by four Yb(III) complexes, which exhibit bimodal red and NIR fluorescence signals upon photoexcitation of the porphyrin π system. Single-crystal X-ray structural analysis and computational molecular modeling revealed that planar aromatic perfluorocarbons were intercalated into the MOC. The tight packing between the MOC and guests enhanced the NIR fluorescence of Yb(III) by suppressing energy transfer from the photoexcited porphyrin to oxygen molecules. Guest-responsive turn-on NIR fluorescence changes in an MOC were successfully demonstrated.

MicroRNA-326 negatively regulates CD155 expression in lung adenocarcinoma.

Treatment with immune checkpoint inhibitors induces a durable response in some patients with non-small-cell lung cancer, but eventually gives rise to drug resistance. Upregulation of CD155 expression is implicated as one mechanism of resistance to programmed death receptor-1 (PD-1)/PD-1 ligand (PD-L1) inhibitors, and it is therefore important to characterize the mechanisms underlying regulation of CD155 expression in tumor cells. The aim of this study was to identify microRNAs (miRNAs) that might regulate CD155 expression at the posttranscriptional level in lung cancer. Comprehensive miRNA screening with target prediction programs and a dual-luciferase reporter assay identified miR-346, miR-328-3p, miR-326, and miR-330-5p as miRNAs that bind to the 3'-UTR of CD155 mRNA. Forced expression of these miRNAs suppressed CD155 expression in lung cancer cell lines. Immunohistochemical staining of CD155 in tissue specimens from 57 patients with lung adenocarcinoma revealed the median tumor proportion score for CD155 to be 68%. The abundance of miR-326 in these specimens with a low level of CD155 expression was significantly greater than in specimens with a high level (p < 0.005). Our results thus suggest that miR-326 negatively regulates CD155 expression in lung adenocarcinoma and might therefore play a role in the development of resistance to PD-1/PD-L1 inhibitors.

Structural metamorphosis and photophysical properties of thermostable nano- and microcrystalline lanthanide polymer with flexible coordination chains.

Luminescent lanthanide coordination polymer crystals (LCPCs) represent an area of growing interest in materials chemistry owing to their unique and tailorable functional properties. The LCPCs provide a high level of structural tunability, including size- and morphology-dependent properties; therefore, they are promising materials for next-generation phosphors in a wide range of applications such as light emitting diodes. Here, by controlling the morphology of thermostable europium coordination polymer crystals, [Eu(hfa)3(dpbp)]n, hfa: hexafluoroacetylacetonate and dpbp:4,4'-bis(diphenyl　phosphoryl) biphenyl), we realized a novel red phosphor with narrow linewidth emission (FWHM = 7.8 nm). The obtained luminescent LCPCs with unique structures were characterized by X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), dynamic light scattering (DLS) and thermogravimetric analysis. Among, them, size tunable crystalline polymer spheres were found to have high internal quantum efficiency (ex., IQE = 79%) and highly thermostability (>300°C), and to exhibit dispersibility in PMMA media. The obtained results on the structural tunability of these materials can be used for the development of synthesis techniques for nanoscale materials based on crystalline lanthanide-based coordination phosphors.

Deep-red to near-infrared luminescence from Eu2+-trapped exciton states in YSiO2N.

The valence state of Eu ions doped in inorganic compounds is easily influenced by the synthesizing conditions. In this study, X-ray absorption spectroscopy revealed that almost half of Eu ions incorporated in the YSiO2N host were reduced into the divalent state through the sintering process at 1600 °C under a N2 gas atmosphere without any annealing processes. The prepared Eu2+/3+-doped YSiO2N sample showed anomalous deep-red to near-infrared luminescence below 300 K under violet light illumination, whose luminescent properties are discussed through detailed spectroscopic analyses. In the photoluminescence spectra at 4 K, the broad luminescence band ranging from 550 to 1100 nm with a large Stokes shift of 5677 cm-1 was observed, assigned to the recombination emission related to the Eu2+-trapped exciton state. The temperature dependence of luminescence lifetime suggests that the thermal quenching of Eu2+-trapped exciton luminescence takes place through complicated processes in addition to thermal ionization. The energy diagrams based on the spectroscopic results indicate that Eu2+-trapped exciton luminescence in the YSiO2N:Eu2+/3+ sample was observed because all the Eu2+: 5d excited levels are degenerated with the host conduction band, and the relatively stable Eu2+-trapped exciton state in the Y3+ sites is formed just below the conduction band bottom. A comprehensive discussion on the deep-red to near-infrared luminescence in the YSiO2N host could give new insights into the mechanism of Eu2+-trapped exciton luminescence in Y3+ sites, which has potential in near-infrared emitting devices.

Factors related to daily step counts of stroke patients during hospitalization in a convalescent rehabilitation ward.

OBJECTIVES: Clarifying the factors related to decreased physical activity in post-stroke patients is essential for effective disease management. This study aimed to examine the factors influencing the amount of daily steps taken by post-stroke patients in a convalescent rehabilitation ward during activities other than rehabilitation (non-rehabilitation steps). MATERIALS AND METHODS: Eighty-nine post-stroke patients (60.8±14.4 years; 55 men) were enrolled. The inclusion criteria were walking independently within the ward and having a walking speed of ≥24 m/min. Data on patient clinical characteristics including age, sex, body mass index, stroke type, hemiparetic side, and time from stroke onset were collected. Stroke impairment and motor and cognitive functional disabilities were assessed using the Stroke Impairment Assessment Set and the Functional Independence Measure, respectively. The non-rehabilitation steps were calculated by subtracting the steps during the rehabilitation activities from the total steps using Fitbit Flex2. RESULTS: The average number of non-rehabilitation steps was 4,523±2,339 steps/day. The hierarchical multiple regression analysis revealed that sex, motor disability, and the interaction term of stroke impairment with cognitive disability were significantly related to non-rehabilitation steps. Simple slope analysis demonstrated that the stroke impairment slope was steeper at lower levels than at higher levels of cognitive disability for non-rehabilitation steps. CONCLUSIONS: In addition to independent effects of sex and motor disability, this study found that stroke impairment and cognitive disability were interactively related to non-rehabilitation steps in post-stroke patients in a convalescent rehabilitation ward. These findings may provide useful information for managing physical activity in post-stroke patients after hospital discharge.

Dissimilarity measure of local structure in inorganic crystals using Wasserstein distance to search for novel phosphors.

To efficiently search for novel phosphors, we propose a dissimilarity measure of local structure using the Wasserstein distance. This simple and versatile method provides the quantitative dissimilarity of a local structure around a center ion. To calculate the Wasserstein distance, the local structures in crystals are numerically represented as a bag of interatomic distances. The Wasserstein distance is calculated for various ideal structures and local structures in known phosphors. The variation of the Wasserstein distance corresponds to the structural variation of the local structures, and the Wasserstein distance can quantitatively explain the dissimilarity of the local structures. The correlation between the Wasserstein distance and the full width at half maximum suggests that candidates for novel narrow-band phosphors can be identified by crystal structures that include local structures with small Wasserstein distances to local structures of known narrow-band phosphors. The quantitative dissimilarity using the Wasserstein distance is useful in the search of novel phosphors and expected to be applied in materials searches in other fields in which local structures play an important role.

Circularly Polarized Absorption and Luminescence of Semiconductor Eu-OCN Nanocrystals in the Blue Region of the Electromagnetic Spectrum.

Semiconductor nanomaterials with efficient polarized-light control in the blue region of the visible spectrum are promising candidates for modern and future photo-information technology, display devices, and optical sensing applications. New-type semiconductor Eu(OCN)2 nanocrystals with circularly polarized absorption (CD: circular dichroism) and emission (CPL: circularly polarized luminescence) under an applied magnetic field are demonstrated here for the first time. The effective CD signal at 1.6 T was observed at approximately 440 nm. The dissymmetry factor of CPL under 100 K, gM-CPL, was estimated to be 0.01. These characteristic circularly polarized absorption and emission phenomena of Eu(OCN)2 nanocrystals should be caused by combination between the "Faraday A and C terms" of the magnetic moment in the excited state. Polarized-light control using Eu(OCN)2 nanocrystals in the blue-light region of the electromagnetic spectrum is a large first step into a new world of photo-functional semiconductor nanomaterials.

The Role of π-f Orbital Interactions in Eu(III) Complexes for an Effective Molecular Luminescent Thermometer.

Luminescent Eu(III) complexes with a ligand-to-metal charge transfer (LMCT) state were demonstrated for the development of a molecular thermometer. The Eu(III) complex was composed of three anionic ligands (hfa: hexafluoroacetylacetonate) and a phosphine oxide derivative containing a chrysene framework (diphenylphosphorylchrysene (DPCO)). The chrysene framework induced a rigid coordination structure via intermolecular interactions, resulting in a high thermal stability (decomposition point: 280 °C). The Eu(III) complex also exhibited an extremely high molar absorption coefficient (490000 cm-1 M-1), high intrinsic emission quantum yields (73%), and temperature-dependent energy migration between ligands and Eu(III) ion. The characteristic energy migration system was explained by the presence of the LMCT state based on π-f orbital interactions.

Near-IR Luminescent YbIII Coordination Polymers Composed of Pyrene Derivatives for Thermostable Oxygen Sensors.

Oxygen-sensitive and near-infrared (NIR) luminescent YbIII coordination polymers incorporating ligands based on pyrene derivatives were synthesized: YbIII -TBAPy and YbIII -TIAPy (TBAPy: 1,3,6,8-tetrakis(p-benzoate)pyrene; TIAPy: 1,3,6,8-tetrakis(3,5-isophthalic acid)pyrene). The coordination structures of these materials have been characterized by means of electrospray ionization mass spectrometry, X-ray diffraction analysis, and thermogravimetric analysis. Moreover, the porous structure of YbIII -TIAPy has been evaluated by measuring its N2 adsorption isotherm. The NIR luminescence properties of YbIII -TBAPy and YbIII -TIAPy have been examined by acquiring emission spectra and determining emission lifetimes under air or argon and in vacuo. YbIII -TIAPy exhibited high thermal stability (with a decomposition temperature of 400 °C), intense luminescence (with an emission quantum yield under argon of 6.6 %), and effective oxygen-sensing characteristics. These results suggest that NIR luminescent YbIII coordination polymers prepared using pyrene derivatives could have applications in novel thermo-stable oxygen sensors.

Perfluorophenyl-Directed Giant Porphyrin J-Aggregates.

Quadrupolar interactions of porphyrin bearing two pentafluorophenylethynyl terminals (1) drove the formation of a successive one-dimensional staircase structure, i.e., J-aggregates, to yield millimeter-length needles with a single-crystalline character in methylcyclohexane solution. In contrast, π-stacked interactions of porphyrin bearing two nonfluorinated phenyl terminals (2) formed no aggregates in solution. A spin-cast film of 1 also showed bathochromic shift of the Soret and Q bands, indicating the formation of J-aggregates. The molecular arrangement of the J-aggregates was revealed by microbeam glazing-incidence wide-angle X-ray diffraction (GIWAXD), and was in good agreement with the optimized structure generated by density functional theory (DFT) calculations.

Ligand-Assisted Back Energy Transfer in Luminescent TbIII Complexes for Thermosensing Properties.

A luminescent TbIII complex with a hexafluoroacetylacetone (hfa) ligand shows a characteristic back energy transfer (BEnT), which leads to high temperature sensitivity and potential application as a thermosensitive paint. Ligand-assisted BEnT was observed when a phosphine oxide ligand was introduced into Tb(hfa)3 complex, which was shown to affect the activation energy (ΔEa ) and frequency factor (A) in the BEnT process between TbIII ion and hfa ligands. According to temperature-dependent emission-lifetime measurements of mononuclear Tb(hfa)3 complexes with monodentate phosphine oxides and polynuclear Tb(hfa)3 complexes with bidentate phosphine oxides, the ΔEa and A values of polynuclear TbIII complexes were smaller than those of mononuclear TbIII complexes. Phosphorescence spectra and lifetimes of each Gd(hfa)3 complex revealed that excited states of hfa ligands in TbIII complexes differed from those of the polynuclear TbIII complexes and mononuclear TbIII complexes. The differences in the ΔEa and A values between polynuclear and mononuclear TbIII complexes were caused by the formation of different excited states, such as delocalization of the excited state in the polynuclear TbIII complexes and localization of excited states in the mononuclear TbIII complexes. In particular, small ΔEa and A values of polynuclear TbIII complexes provided high, effective activation of the BEnT at low temperature, which resulted in high-sensitive temperature-dependent phosphor materials over a wide temperature range.

A Luminescent Dinuclear EuIII /TbIII Complex with LMCT Band as a Single-Molecular Thermosensor.

Temperature-dependent luminescence of a dinuclear EuIII /TbIII complex with a seven-coordinate structure is demonstrated. The dinuclear complex is composed of two lanthanide ions, six tetramethylheptanedionate ligands, and a bidentate phosphine oxide linker ligand. The dinuclear structure of the complex was characterized by single-crystal XRD. Intrinsic 4f-4f emission quantum yields of the dinuclear EuIII and TbIII complexes were 66 and 61 %, respectively. The luminescence color of the dinuclear EuIII /TbIII complex changed from red to green with increasing temperature. The thermosensing range based on the ratio of luminescence intensity (AEu /ATb ) was 100-450 K. The temperature-dependent luminescence is due to the presence of a ligand-to-metal charge-transfer state.

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: N,N'-bis(salicylidene)ethylenediamine), brick-type [Eu2(hfa)4(OAc)2(salbn)2] (salbn: N,N'-bis(salicylidene)-1,4-butanediamine), and polynuclear [Eu(hfa)2(OAc)(salhen)] n (salhen: N,N'-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 (Φπ-π* = 47%) and remarkably high efficiency of sensitization (ηsens = 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.

Structural Manipulation of Triboluminescent Lanthanide Coordination Polymers by Side-Group Alteration.

Novel Eu(III) coordination polymers with furan-based bridging ligands [Eu(hfa)3(Cy)] n and [Eu(hfa)3(Tol)] n (hfa: hexafluoroacetylacetonato, Cy: 2,5-bis(dicyclohexylphosphoryl)furan), Tol: 2,5-bis(di- p-tolylphosphoryl)furan) are reported. The rigidity of assembly steric structures was controlled by intermolecular interactions through the side groups in bridging ligands. They exhibited one of the best performances (thermal stability above 320 °C and external photoluminescence quantum yields of up to 71%) among reported lanthanide(III) compounds. The triboluminescence activity was demonstrated to be dependent on the mechanical stability of the coordination polymers, which was proportional to the number of hydrogen atoms in the side groups. The second example of a large TL/PL spectral difference in [Tb,Eu(hfa)3(Tol)] n also revealed discrete photophysical processes under the conditions of grinding and UV irradiation.

Luminescent Mechanochromic 9-Anthryl Gold(I) Isocyanide Complex with an Emission Maximum at 900 nm after Mechanical Stimulation.

Upon mechanical stimulation, 9-anthryl gold(I) isocyanide complex 3 exhibited a bathochromic shift of its emission color from the visible to the infrared (IR) region, which is unprecedented in its magnitude. Prior to exposure to the mechanical stimulus, the polymorphs 3α and 3ß exhibit emission wavelength maxima (λem,max) at 448 and 710 nm, respectively. Upon grinding, the λem,max of 3αground and 3ßground are bathochromically shifted to 900 nm, i.e., Δλem,max (3α) = 452 nm or 1.39 eV. Polymorphs 3α and 3ß thus represent the first examples of mechanochromic luminescent materials with λem,max in the IR region.

Effective Photo- and Triboluminescent Europium(III) Coordination Polymers with Rigid Triangular Spacer Ligands.

Luminescent EuIII coordination polymers with rigid triangular spacer ligands are reported. The EuIII coordination polymer, [Eu3 (hfa)9 (tppb)2 ]n (hfa: hexafluoroacetylacetonate, tppb: tris(4-diphenylphosphorylphenyl)benzene), shows high thermo-stability (decomposition temperature=354 °C) and photoluminescence quantum yield (Φ4f-4f =82 %, photosensitized energy transfer efficiency=78 %). The triboluminescence efficiency of EuIII coordination polymer with triangular spacers under laser pulse irradiation (Nd:YAG, λ=1064 nm, pulse width=5 ns, pulse energy=0.1 mJ) is calculated to be 49 %. Characteristic triangular structure, high emission quantum yield, effective photosensitized energy transfer, and remarkable triboluminescence properties of EuIII coordination polymers are demonstrated for the first time.

Solvent-dependent dual-luminescence properties of a europium complex with helical π-conjugated ligands.

A europium(iii) complex with a large π-conjugated helical ligand, tris(hexafluoroacetylacetonato)europium(iii)bis((pentahelicenyl)diphenylphosphine oxide) (Eu(hfa)3(HPO)2), exhibits dual luminescence excited at the π-π* transition band. In this study, the solvent-dependent photophysical properties of Eu(hfa)3(HPO)2 are reported. The ground-state properties of the ligand and the Eu(iii) complex are assessed from electronic absorption spectra, magnetic circular dichroism spectra, and density functional theory calculations. The excited-state properties of these compounds are evaluated using luminescence spectra, excitation spectra, luminescence lifetimes, and luminescence quantum yields depending on solvents, which are CHCl3, C2H5Br, C2H5I, CH3COCH3, and CD3COCD3. Under all of the examined conditions, the intensity ratios of dual luminescence originating from the ligand and the Eu(iii) ion were strongly dependent on the properties of the solvent. The solvent dependence of the luminescence ratio is discussed in terms of the external heavy atom effect.

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((R)-bidp)]n (hfa: haxafluoroacetylacetonato, (R)-bidp: (R)-1,1'-binaphthyl-2,2'-bis(diphenylphosphinate), is reported. Single-crystal X-ray analysis revealed a characteristic helical polymer structure of [Eu(hfa)3((R)-bidp)]n with hydrogen-fluorine/π interactions. [Eu(hfa)3((R)-bidp)]n 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)]n 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.

Development of Ion-Conductive and Vapoluminescent Porous Coordination Polymers Composed of Ruthenium(II) Metalloligand.

We synthesized two new porous coordination polymers (PCPs) {Ln7(OH)5[Ru(dcbpy)3]4·4nH2O} (Ln7-Ru4; Ln = Ce, Nd) composed of the luminescent ruthenium(II) metalloligand [Ru(4,4'-dcbpy)3]4- ([4Ru]; 4,4'-dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) and lanthanide ions Ln3+ (Ln = Ce, Nd). These two PCPs Ln7-Ru4 are isomorphous with the previously reported PCP La7-Ru4, and the lattice constants (a, c, and unit cell volume V) changed systematically according to the lanthanide contraction. All three Ln7-Ru4 compounds have OH- anion containing porous structures and a large number of hydrate water molecules within the pores, resulting in moderate ion conductivities (10-6-10-7 S cm-1) at 90% relative humidity (RH) and 298 K. In contrast, the structural transformation of Ln7-Ru4 associated with water-vapor adsorption/desorption strongly depends on the lanthanide ion; the Ln7-Ru4 compounds with larger Ln3+ ions recover the original porous structure at lower relative humidities (RH). A similar trend was observed for the ion conduction activation energy, suggesting that the bridging Ln3+ ion plays an important role in the formation of the ion-conductive pathways. La7-Ru4 and Ce7-Ru4 exhibit vapochromic luminescence associated with water vapor adsorption/desorption, arising from the 3MLCT emission of [4Ru]. This vapochromic behavior is also affected by the replacement of the Ln3+ ion; the vapochromic shift of Ce7-Ru4 was observed at RH values (near 100% RH) higher than that of La7-Ru4. 3MLCT emissions of the [4Ru] metalloligand in Nd7-Ru4 were barely observable in the visible region, but sharp emission bands characteristic of 4f-4f transitions of the Nd3+ ion were observed in the near-infrared (NIR) region (arising from the 1MLCT transition of [4Ru]), suggesting the transfer of energy from the [4Ru] 3MLCT excited state to the 4f-4f transition state of the Nd3+ ions.

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.