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Artificial light plays an essential role in information technologies such as optical telecommunications, data storage, security features, and the display of information. Here, we show a chiral lanthanide lumino-glass with extra-large circularly polarized luminescence (CPL) for advanced photonic security device applications. The chiral lanthanide glass is composed of a europium complex with the chiral (+)-3-(trifluoroacetyl)camphor ligand and the achiral glass promoter tris(2,6-dimethoxyphenyl)phosphine oxide ligand. The glass phase transition behavior of the Eu(III) complex is characterized using differential scanning calorimetry. The transparent amorphous glass shows CPL with extra-large dissymmetry factor of g CPL  = 1.2. The brightness of the lumino-glass is one thousand times larger than that of Eu(III) luminophores embedded in polymer films of the same thickness at a Eu(III) concentration of 1 mM. The application of the chiral lanthanide lumino-glass in an advanced security paint is demonstrated. Circularly polarized luminescence from chiral organic molecules is used in devices such as security tags, lasers, or data storage. Here, the authors use (+)-3-(trifluoroacetyl)camphor and a glass-promoting phosphine oxide ligand to achieve a chiral Eu(III) lumino-glass.

The stimulation of photosynthesis is a strategy for achieving sustainable plant production. Red light is useful for plant growth because it is absorbed by chlorophyll pigments, which initiate natural photosynthetic processes. Ultraviolet (UV)-to-red wavelength-converting materials are promising candidates for eco-friendly plant cultures that do not require electric power. In this study, transparent films equipped with a UV-to-red wavelength-converting luminophore, the Eu 3+ complex, were prepared on commercially available plastic films for plant growth experiments. The present Eu 3+ -based films absorb UV light and exhibit strong red luminescence under sunlight. Eu 3+ -painted films provide significant growth acceleration with size increment and biomass production for vegetal crops and trees in a northern region. The plants cultured with Eu 3+ -painted films had a 1.2-fold height and 1.4-fold total body biomass than those cultures without the Eu 3+ luminophores. The present film can promote the plant production in fields of agriculture and forestry.

Soft-crystals are defined as flexible molecular solids with highly ordered structures and have attracted attention in molecular sensing materials based on external triggers and environments. Here, we show the soft-crystal copolymerization of green-luminescent Tb(III) and yellow-luminescent Dy(III) coordination centers. Soft-crystal polymerization is achieved via transformation of monomeric dinuclear complexes and polymeric structures with respect to coordination number and geometry. The structural transformation is characterized using single-crystal and powder X-ray diffraction. The connected Tb(III) crystal-Dy(III) crystal show photon energy transfer from the Dy(III) centre to the Tb(III) centre under blue light excitation (selective Dy(III) centre excitation: 460 ± 10 nm). The activation energy of the energy transfer is estimated using the temperature-dependent emission lifetimes and emission quantum yields, and time-dependent density functional theory (B3LYP) calculations. Luminescence-conductive polymers, photonic molecular trains, are successfully prepared via soft-crystal polymerization on crystal media with remarkable long-range energy migration. Soft-crystals are molecular solids with highly ordered structures. Here, authors report the soft-crystal copolymerization of green-luminescent Tb(III) and yellow-luminescent Dy(III) complexes, and study the long-range energy transfer from one crystal to the other.

Luminescent lanthanide complexes containing effective photosensitizers are promising materials for use in displays and sensors. The photosensitizer design strategy has been studied for developing the lanthanide-based luminophores. Herein, we demonstrate a photosensitizer design using dinuclear luminescent lanthanide complex, which exhibits thermally-assisted photosensitized emission. The lanthanide complex comprised Tb(III) ions, six tetramethylheptanedionates, and phosphine oxide bridge containing a phenanthrene frameworks. The phenanthrene ligand and Tb(III) ions are the energy donor (photosensitizer) and acceptor (emission center) parts, respectively. The energy-donating level of the ligand (lowest excited triplet (T 1 ) level = 19,850 cm −1 ) is lower than the emitting level of the Tb(III) ion ( 5 D 4 level = 20,500 cm −1 ). The long-lived T 1 state of the energy-donating ligands promoted an efficient thermally-assisted photosensitized emission of the Tb(III) acceptor ( 5 D 4 level), resulting in a pure-green colored emission with a high photosensitized emission quantum yield (73%). Luminescent lanthanide complexes are promising materials for use in displays and sensors, however, these materials often undergo thermal quenching. Here, the authors synthesize and characterize a terbium dinuclear phosphine oxide-bridged phenanthrene complex, which exhibits thermally-enhanced emission.

Accurate determination of human tumor malignancy is important for choosing efficient and safe therapies. Bioimaging technologies based on luminescent molecules are widely used to localize and distinguish active tumor cells. Here, we report a human cancer grade probing system (GPS) using a water-soluble and structure-changeable Eu(III) complex for the continuous detection of early human brain tumors of different malignancy grades. Time-dependent emission spectra of the Eu(III) complexes in various types of tumor cells were recorded. The radiative rate constants ( k r ), which depend on the geometry of the Eu(III) complex, were calculated from the emission spectra. The tendency of the k r values to vary depended on the tumor cells at different malignancy grades. Between T = 0 and T = 3 h of invasion, the k r values exhibited an increase of 4% in NHA/TS (benign grade II gliomas), 7% in NHA/TSR (malignant grade III gliomas), and 27% in NHA/TSRA (malignant grade IV gliomas). Tumor cells with high-grade malignancy exhibited a rapid upward trend in k r values. The cancer GPS employs Eu(III) emissions to provide a new diagnostic method for determining human brain tumor malignancy.

Photosensitizer design to allow effective use of low-energy light is important for developing photofunctional materials. Herein, we describe a rational photosensitizer design for effective use of low-energy light. The developed photosensitizer is a stacked nanocarbon based on a rigid polyaromatic framework, which allows efficient energy transfer from the low-energy T 1 level to the energy acceptor. We prepared an Eu(III) complex consisting of a luminescent center (Eu(III)) and stacked-coronene photosensitizer. The brightness of photosensitized Eu(III) excited using low-energy light (450 nm) is more than five times higher than the maximum brightness of previously reported Eu(III) complexes. Rational photosensitizer design for the effective use of low-energy light is important for photofunctional materials. Here the authors develop a stacked nanocarbon photosensitizer based on a rigid polyaromatic framework, which allows efficient energy transfer to a Eu(III) center.

Photoinduced metal-to-ligand (or ligand-to-metal) charge-transfer (CT) states in metal complexes have been extensively studied toward the development of luminescent materials. However, previous studies have mainly focused on CT transitions between d- and π-orbitals. Herein, we report the demonstration of CT emission from 4f- to π-orbitals using a trivalent europium (Eu(III)) complex, supported by both experimental and theoretical analyses. The Eu(III) complex exhibits an eight-coordination structure, comprising three anionic nitrates and two neutral electron-donating ligands containing a carbazole unit. The diffuse reflectance spectrum of the complex displays an absorption band at 440 nm and time-resolved emission analyses reveal a characteristic emission band at 550 nm. Comparative studies employing a trivalent gadolinium (Gd(III)) complex, alongside quantum chemical analyses, confirm that the observed absorption and emission bands are associated with CT transitions between π- and 4f-orbitals. The observation of CT emission based on the 4f-orbital offers novel insights into the field of molecular luminescence science and technology. Photoinduced metal-to-ligand (or ligand-to-metal) charge-transfer (CT) states in metal complexes have been extensively studied, but primarily limited to CT transitions between d- and π-orbitals. Here, CT emission from 4f- to π-orbitals is demonstrated using a trivalent europium complex.

The cover picture shows a photosensitizer that has a long excited‐state lifetime and provides strong emissions for TbIII coordination polymers. The coordination polymers are composed of TbIII ions (emission center), hexafluoroacetylacetonato (photosensitizer ligands), and phosphine oxide‐based bridges (ancillary ligands). The photosensitizer with a long excited‐triplet‐state lifetime (τ≥1120 μs) controls the excited state equilibrium between the photosensitizer and TbIII, allowing the construction of TbIII coordination polymer with high TbIII emission quantum yield. More information can be found in the Research Article by Y. Kitagawa, Y. Hasegawa, and co‐workers.

The redox behaviors of macrocyclic molecules with an entirely π-conjugated system are of interest due to their unique optical, electronic, and magnetic properties. In this study, defect-free cyclic P3HT with a degree of polymerization (DPn) from 14 to 43 was synthesized based on our previously established method, and its unique redox behaviors arising from the cyclic topology were investigated. Cyclic voltammetry (CV) showed that the HOMO level of cyclic P3HT decreases from –4.86 eV (14 mer) to –4.89 eV (43 mer), in contrast to the linear counterparts increasing from –4.94 eV (14 mer) to –4.91 eV (43 mer). During the CV measurement, linear P3HT suffered from electro-oxidation at the chain ends, while cyclic P3HT was stable. ESR and UV–Vis–NIR spectroscopy suggested that cyclic P3HT has stronger dicationic properties due to the interactions between the polarons. On the other hand, linear P3HT showed characteristics of polaron pairs with multiple isolated polarons. Moreover, the dicationic properties of cyclic P3HT were more pronounced for the smaller macrocycles.

The chiral nonanuclear Tb(III) clusters [Tb 9 (sal-( R )-Bt) 16 ( μ -OH) 10 ] + [NO 3 ] − (Tb-( R )-Bt: sal-( R )-Bt=( R )-2-butyl salicylate) and [Tb 9 (sal-( S )-Bt) 16 ( μ -OH) 10 ] + [NO 3 ] − (Tb-( S )-Bt: sal-( S )-Bt=( S )-2-butyl salicylate) were found to exhibit a unique magneto-optical property: the Faraday effect. The clusters were composed of 9 Tb(III) ions bridged by 10 μ -OHs and 16 chiral salicylic acid esters. The Faraday rotation angle of Tb-( R )-Bt was greater than that of Tb-( S )-Bt, indicating that the Faraday effect was affected by the chirality of the Tb(III) clusters. The chiroptical properties of the Tb(III) clusters were estimated using circular dichroism and circularly polarized luminescence. In this study, a new finding concerning chiral magneto-optical properties was investigated. Chirality: unexpected twists from chiral clusters By pairing chiral organic ligands with rare-earth clusters, scientists have gained surprising insights into magneto-optical material design. Many optical telecommunication devices use the Faraday effect — a means of rotating the polarization of light using magnetic fields — to prevent unwanted light transmissions. Now, Yasuchika Hasegawa from Hokkaido University in Japan and co-workers have observed the first-ever correlation between the Faraday effect and molecular chirality. The Faraday effect is traditionally viewed as being insensitive to natural optical activity such as chirality. But the team's previous investigations, which showed organic ligands influenced promising Faraday materials known as terbium glasses, inspired them to challenge long-held assumptions. They synthesized nine-membered terbium clusters and complexed them with chiral salicylate ligands. Different ligand chirality categorically affected the Faraday rotation angles — an effect that may arise from terbium's large transition magnetic dipole. Naturally occurring and magnetically induced optical activities (the Faraday effect) have contributed to our understanding of molecular electronic states, and have also had various applications in photonics. It has been generally considered that the Faraday effect is not affected by natural optical activity originating from chirality. Herein we describe for the first time a relationship between the Faraday rotation angles and chirality in a chiral lanthanide cluster. This finding provides new insights into the design of next-generation molecular Faraday materials and may lead to the development of a novel area of study within the field of chiral science.