In the fields of fluid dynamics, aeronautical engineering, environment engineering, and energy technology, it is critical to accurately measure the physical parameters of a material surface. [1] Optoelectronic devices have generally been employed as temperature and pressure sensors. [2] However, their sensing area is limited to a single point on a surface. There is a need to measure entire surfaces and obtain multidimensional data for mapping surfaces. There are high expectations that materials for surface measurements, such as temperature and pressure-sensitive dyes, will overcome this intrinsic limitation of optoelectronic devices.We seek to design temperature-sensitive dyes using luminescent lanthanide complexes. Lanthanide complexes exhibit characteristic luminescence with narrow emission bands (full width at half maximum, fwhm < 10 nm) and long emission lifetimes (> 1 ms), [3] which make them suitable for use in sensing devices. In 2003, Amao and co-workers reported the first temperature-sensitive dye that employed an Eu III complex in a polymer film. [4] Khalil et al. demonstrated the high performance of an Eu III complex for a temperature-sensitive paint (temperature sensitivity: 4.42 % 8C À1 ). [5] We have reported a Tb III complex, Tb(hfa) 3 -(H 2 O) 2 (hfa: hexafluoro acetylacetonato), that is suitable as a temperature-sensing probe since it exhibits effective energy back transfer (BEnT) from the emitting level of the Tb III ion to the excited triplet state of the hfa ligand. [6] Since BEnT depends on the energy barrier of the process, the emission intensity varies with temperature.To improve the thermosensing performance, it is necessary to develop a thermostable structure for high-temperature sensing and to implement a dual sensing unit for a high sensing ability. First, we focused on a lanthanide coordination polymer to produce a thermostable structure. Thermally stable coordination polymers and metal-organic frameworks have been widely studied. [7] Carlos and co-workers recently reported novel three-dimensional lanthanide-organic frameworks with 2,5-pyridinedicarboxylic acid. [8] Marchetti et al. developed thermostable Eu III coordination polymers with 4acyl-pyrazolone ligands. [9] Here, we consider that introducing Tb III ion and hfa ligands to coordination polymer frameworks will produce a Tb III coordination polymer that can be used as a temperature-sensing probe. The triplet state of hfa (22 000 cm À1 ) is very close to the emitting level of the Tb III ion (20 500 cm À1 ), resulting in effective EnT1 and BEnT and thus high-performance thermosensing dyes (Figure 1 a). We also selected low-vibrational frequency phosphane oxide [10] as the linking part in the Tb III coordination polymer because lanthanide complexes with high emission quantum yields composed of hfa and bidentate phosphane oxide ligands have been reported. [11] Second, we attempted to impart ratiometric temperature sensing by using luminescent Eu III and Tb III ions in the frameworks of the coordination polymer to realize a high th...

Photocurrent excitation spectra were measured to investigate the quenching in the garnet solid solutions. Intense photocurrent excitation bands attributed to the lowest 5d 1 and the second lowest 5d 2 levels were observed in the Ce-doped Y 3 Al 2 Ga 3 O 12 (Ce:YAGG) and Y 3 Ga 5 O 12 (Ce:YGG). Based on the results of temperature dependence of photoconductivity, the 5d 1 and 5d 2 levels in the Ce:YAGG are found to be located below and within the conduction band, respectively, while both levels in the Ce:YGG are found to be located within its conduction band located at lower energy levels. In addition, the threshold of photoionization from the 4f level of Ce 3þ to the conduction band in the Ce:YAGG and Ce:YGG were estimated to be 3.2, and 2.8 eV, respectively. We conclude that the main quenching process in the Ce:YAGG is caused by the thermally stimulated ionization process with activation energy of 90 meV from the 5d 1 to the conduction band, and that in the Ce:YGG is caused by the direct ionization process from the 5d levels to the conduction band.

The 4f-4f emission of Tb(III), Eu(III), and Sm(III) complexes plays an important role in the design of monochromatic green, red, and deep-red luminescent materials for displays, lighting, and sensing devices. The 4f-4f emission of Yb(III), Nd(III), and Er(III) complexes is observed in the near-infrared (IR) region for bioimaging and security applications. However, their absorption coefficients are extremely small (ε < 10 L mol −1 cm −1 ). In this review, photosensitized luminescent lanthanide(III) complexes containing organic chromophores (ligands) with large absorption coefficients (ε > 10,000 L mol −1 cm −1 ) are introduced. Organic molecular design elements, including (1) the control of the excited triplet (T 1 ) state, (2) the effects on the charge-transfer (CT) band, and (3) the energy transfer from metal ions for effective photosensitized luminescence, are explained. The characteristic electrosensitized luminescence (electroluminescence) and mechanoluminescence (triboluminescence) of lanthanide(III) complexes are also explained. Lanthanide(III) complexes with well-designed organic molecules are expected to open avenues of research among the fields of chemistry, physics, electronics, and material science.

An organometallic Au 13 cluster having two σ--bonded acetylide ligands was synthesized and its structure was determined by X--ray crystllography. Absorption spectral studies indicated the presence of the electronic coupling between the superatomic Au13 core and the acetylide π--orbitals, which was supported by theoretical considerations.Gold-acetylide sigma bonds have been of general interest as they bring about the emergence of unique optical properties and reactive intermediates in catalysis. [1][2][3][4][5][6][7][8][9] For simple metal complexes, rich chemistry has been explored from both functional and structural perspectives. On the other hand, although numerous ligand-protected gold clusters have been synthesized, 10-14 examples of alkynyl-ligated clusters have been quite rare to date, and the nature of the bonding and electronic interaction between a cluster kernel and a C≡C π-system has not been experimentally characterized. [15][16][17][18] Tsukuda et al. have observed no appreciable electronic interaction in the optical absorption spectra of alkyne-protected gold clusters of diameter > 1 nm. 15,16 We have also demonstrated a similar phenomenon for a structurally precise Au 8 cluster with an anisotropic core+exo-type structure. 17 Herein we report the first experimental evidence of electronic interaction between a polyhedral gold core and a σ-bonded π-unit in the absorption spectrum of a phenylethynyl-modified Au 13 cluster with an icosahedral geometry and superatomic 8-electron system. [19][20][21][22] We have also investigated its electronic structure based on DFT calculations, which support the presence of electronic interaction between the superatomic gold core and π-conjugated units.Regioselective introduction of two alkynyl ligands on the surface of the icosahedral Au 13 skeleton was achieved by the ligand-exchange reaction of a dichloro-substituted Au 13 cluster cation ([Au 13 (dppe) 5 Cl 2 ](PF 6 ) 3 , 1·(PF 6 ) 3 ), which was synthesized according to the HCl-mediated post-synthetic method. 20 The reaction cleanly proceeded by employing excess amounts of terminal alkynes and base (sodium methoxide), and the complete ligand exchange was verified by electrospray ionization mass spectrometry (ESI-MS) analysis of the reaction mixture. After workup, the crude product was recrystallized from acetonitrile and diethyl ether to give the pure dialkynylsubstituted cluster as its hexafluorophosphate salt ([Au 13 (dppe) 5 (C≡CPh) 2 ](PF 6 ) 3 , 2·(PF 6 ) 3 ), which was thoroughly characterized by ESI-MS analyses, elemental analyses, X-ray crystallography, and 1 H and 31 P NMR spectroscopies. For instance, the ESI mass spectrum of 2·(PF 6 ) 3 showed a set of signals around m/z 1585, in perfect agreement with the calculated isotope pattern for [Au 13 (dppe) 5 (C≡CPh) 2 ] 3+ (Fig. S2). Single-crystal X-ray analysis of 2·(PF 6 ) 3 revealed that the cluster core adopts an icosahedral geometry. Two alkynyl ligands are σ-coordinated to the two diagonal apexes (Au1 and Au1′) of the icosahedron from the trans positio...

Luminescent lanthanide coordination polymers composed of lanthanide ions and organic joint ligands exhibit characteristic photophysical and thermostable properties that are different from typical organic dyes, luminescent metal complexes, and semiconductor nanoparticles.

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 3β exhibit emission wavelength maxima (λ) at 448 and 710 nm, respectively. Upon grinding, the λ of 3α and 3β are bathochromically shifted to 900 nm, i.e., Δλ (3α) = 452 nm or 1.39 eV. Polymorphs 3α and 3β thus represent the first examples of mechanochromic luminescent materials with λ in the IR region.

Novel thermostable organo‐phosphor compounds composed of coordination polymers are reported. Tight‐binding structures with intermolecular interactions of the coordination polymer induce both thermostability (decomposition point >300 °C) and high emission quantum yield (ΦLn=83 %). Their structures (see picture), thermogravimetric analyses, and remarkable photophysical properties are presented for the first time.

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