Type I interferon is critical for the homeostasis and functional maturation of type 3 γδ T cells

Iridium­(III) cyclometalates (<b>1c</b> and <b>2c</b>) in which the two carborane units on the 4- or 5-positions of 2-phenylpyridine (ppy) ligands were tethered by an alkylene linker were prepared to investigate the effect of free rotation of <i>o</i>-carborane on phosphorescence efficiency. In comparison with the unlinked complex, tethering the <i>o</i>-carboranes to the 5-positions of ppy ligands (<b>2c</b>) enhanced phosphorescence efficiency by over 30-fold in polar medium (Φ_PL = 0.37 vs 0.011 in THF), while restricting the rotation of <i>o</i>-carborane at the 4-positions (<b>1c</b>) negatively affected the phosphorescence efficiency. The different effects of restricted rotation of <i>o</i>-carborane on phosphorescence efficiency were likely a result of the different variations of the carboranyl C–C bond distances in the excited state

<i>o</i>‑Carboranyl–Phosphine as a New Class of Strong-Field Ancillary Ligand in Cyclometalated Iridium(III) Complexes: Toward Blue Phosphorescence

Heteroleptic tris-cyclometalated Ir­(III) complexes supported by the <i>o</i>-carboranyl–phosphine ligand (<i>CBP</i>), (C^∧N)₂Ir­(<i>CBP</i>) (C^∧N = <i>ppy</i> (<b>1</b>), <i>dfppy</i> (<b>2</b>)), have been synthesized and characterized. The PL spectra of <b>1</b> and <b>2</b> displayed substantially blue shifted phosphorescence relative to the corresponding Ir­(C^∧N)₃ complexes. Electrochemical and theoretical studies showed that the <i>CBP</i> ligand functioned as a strong-field ancillary ligand, and the greater HOMO stabilization in comparison to that of the LUMO by the <i>CBP</i> ligand was responsible for the increase in band gap, leading to a large blue shift in phosphorescence

Effect of Rare-Earth Element Doping on NiFe-Layered Double Hydroxides for Water Oxidation at Ultrahigh Current Densities

Electrochemical energy conversion processes such as water reduction to produce hydrogen and carbon dioxide reduction into valuable carbon products have attracted great attention as alternative green energy technologies to fossil fuels. Nevertheless, the conversion efficiency and long-term stability of these technologies remain very far from the requirements for industrial applications because of the sluggish kinetics of the oxygen evolution reaction (OER). In this study, La-doped NiFe-layered double hydroxides (LDHs) were synthesized on Ni foam via a facile hydrothermal method and applied as active and stable OER electrochemical catalysts. The La-doped NiFe-LDH having the optimal La doping level exhibits excellent OER catalytic activity with a low overpotential of 309 mV at a high current density of 500 mA cm–2, a low Tafel slope of 42 mV dec–1, and long-term stability in the OER process over 140 h at 100 mA cm–2. Remarkably, the full cell of NiFeLa LDH-2||NiMoOx achieves high current densities of 500 mA cm–2 at the voltage of 1.728 V with superior stability for overall water splitting during 600 h in 1 M KOH. The enhanced OER performance is ascribed not only to the high crystallinity of the nanosheet structure but also to the synergistic electronic interactions between Ni, Fe, and La, which result in a stronger metal–oxygen bond based on d-band theory, more exposed active sites with high-valence states, and increased oxygen vacancies

Deboronation-Induced Turn-on Phosphorescent Sensing of Fluorides by Iridium(III) Cyclometalates with <i>o</i>‑Carborane

Heteroleptic tris-cyclometalated Ir­(III) complexes bearing an <i>o</i>-carborane at the 4- or 5-position in the phenyl ring of the ppy ligand (<i>closo</i>-<b>1</b> and -<b>2</b>) were prepared and characterized. The X-ray crystal structure of <i>closo</i>-<b>1</b> reveals the <i>fac</i> arrangement of the three C^∧N chelates around the Ir atom. Treatment of <i>closo</i> complexes with fluoride anions led to selective deboronation of the <i>closo</i>-carborane cage, producing the corresponding <i>nido</i>-carborane-substituted complexes (<i>nido</i>-<b>1</b> and <b>-2</b>). Whereas <i>closo</i>-<b>1</b> and -<b>2</b> were almost nonemissive in THF, <i>nido</i>-<b>1</b> and -<b>2</b> were highly phosphorescent (Φ_PL = 0.94–0.95). Theoretical studies suggested that, while the emission quenching in <i>closo</i>-<b>1</b> can be ascribed to the substantial involvement of <i>o</i>-carborane in the ³MLCT excited state, the intraligand charge transfer (³ILCT) state from the <i>nido</i>-carborane to pyridyl moieties is responsible for the efficient phosphorescence in <i>nido</i>-<b>1</b>. The addition of fluoride to the buffered THF/H₂O solution (1/1, v/v, pH 7) of <i>closo</i>-<b>1</b> and -<b>2</b> under mild heating led to strong emission intensity, allowing the turn-on phosphorescence detection of fluoride in aqueous medium at the ppb level

High-Performance Piezoelectric Nanogenerators via Imprinted Sol–Gel BaTiO₃ Nanopillar Array

We report high-performance piezoelectric nanogenerators (PENGs) with nanoimprinted sol–gel BaTiO₃ (BTO) nanopillar array polarized under high electric field and ultraviolet. The PENGs fabricated using this method demonstrate greatly enhanced output voltage of ∼10 V and current density of ∼1.2 μA cm^–2, respectively, in comparison to that of flat PENG. Further, the PENG demonstrates uniform output characteristics over the entire device area thanks to uniform nanoimprint pillar array. The approach introduced here is simple, effective, reliable, and reproducible way to fabricate high-performance sol–gel-based PENGs and electronic devices

Terpyridine–Triarylborane Conjugates for the Dual Complexation of Zinc(II) Cation and Fluoride Anion

A series of ditopic terpyridine–triarylborane conjugates (<b>1</b>–<b>3</b>) in which 4′-ethynylterpyridine is linked to the para, meta, and ortho positions of the phenyl ring of dimesitylphenylborane (Mes₂PhB), respectively, were prepared to investigate the dual complexation behavior of the conjugates toward Zn­(II) cation and fluoride anion. The crystal structures of the corresponding Zn­(II) complexes (<b>L</b>·ZnCl₂, <b>L</b> = <b>1</b>–<b>3</b>) reveal the formation of a 1:1 adduct between ZnCl₂ and a conjugate, with a five-coordinate Zn­(II) center bound to three nitrogen atoms and two chlorine atoms. In particular, the structure of ortho-substituted <b>3</b>·ZnCl₂ in comparison with that of <b>3</b> indicates the presence of π–π interactions between the mesityl ring and ethynylene–pyridine fragment in <b>3</b>·ZnCl₂. UV/vis absorption and fluorescence spectra of <b>1</b>–<b>3</b> display low-energy bands mainly assignable to a π­(Ar) → p_π(B) (Ar = Mes and/or phenylene–ethynylene) charge transfer (CT) transition. The transition in Zn­(II) complexes has a π­(Mes) → π*­(Ar) (Ar = terpyridine–ethynylene) intramolecular CT nature with red shifts of both the absorption and emission bands in comparison to those of free conjugates. These spectroscopic features are further supported by TD-DFT calculations. UV/vis absorption and fluorescence titration experiments of <b>1</b>–<b>3</b> toward Zn­(II) and fluoride ion, respectively, show that while the absorption and fluorescence bands underwent gradual quenching upon addition of fluoride, the addition of ZnCl₂ gave rise to the red shifts of both bands. Fluoride titration experiments of Zn­(II) complexes also resulted in gradual quenching of both the absorption and emission bands accompanied by the disappearance of emission color. Sequential addition of ZnCl₂ and fluoride to the conjugates reproduced the above binding behavior with an emission color change from deep blue to sky blue to dark

Terpyridine–Triarylborane Conjugates for the Dual Complexation of Zinc(II) Cation and Fluoride Anion

A series of ditopic terpyridine–triarylborane conjugates (<b>1</b>–<b>3</b>) in which 4′-ethynylterpyridine is linked to the para, meta, and ortho positions of the phenyl ring of dimesitylphenylborane (Mes₂PhB), respectively, were prepared to investigate the dual complexation behavior of the conjugates toward Zn­(II) cation and fluoride anion. The crystal structures of the corresponding Zn­(II) complexes (<b>L</b>·ZnCl₂, <b>L</b> = <b>1</b>–<b>3</b>) reveal the formation of a 1:1 adduct between ZnCl₂ and a conjugate, with a five-coordinate Zn­(II) center bound to three nitrogen atoms and two chlorine atoms. In particular, the structure of ortho-substituted <b>3</b>·ZnCl₂ in comparison with that of <b>3</b> indicates the presence of π–π interactions between the mesityl ring and ethynylene–pyridine fragment in <b>3</b>·ZnCl₂. UV/vis absorption and fluorescence spectra of <b>1</b>–<b>3</b> display low-energy bands mainly assignable to a π­(Ar) → p_π(B) (Ar = Mes and/or phenylene–ethynylene) charge transfer (CT) transition. The transition in Zn­(II) complexes has a π­(Mes) → π*­(Ar) (Ar = terpyridine–ethynylene) intramolecular CT nature with red shifts of both the absorption and emission bands in comparison to those of free conjugates. These spectroscopic features are further supported by TD-DFT calculations. UV/vis absorption and fluorescence titration experiments of <b>1</b>–<b>3</b> toward Zn­(II) and fluoride ion, respectively, show that while the absorption and fluorescence bands underwent gradual quenching upon addition of fluoride, the addition of ZnCl₂ gave rise to the red shifts of both bands. Fluoride titration experiments of Zn­(II) complexes also resulted in gradual quenching of both the absorption and emission bands accompanied by the disappearance of emission color. Sequential addition of ZnCl₂ and fluoride to the conjugates reproduced the above binding behavior with an emission color change from deep blue to sky blue to dark

Phosphorescence Color Tuning of Cyclometalated Iridium Complexes by <i>o</i>‑Carborane Substitution

Heteroleptic (<i>C</i>^∧<i>N</i>)₂Ir­(acac) (<i>C</i>^∧<i>N</i> = 4-<i>CBppy</i> (<b>1</b>); 5-<i>CBppy</i> (<b>2</b>), 4-<i>fppy</i> (<b>4</b>) <i>CB</i> = <i>ortho</i>-methylcarborane; <i>ppy</i> = 2-phenylpyridinato-C²,N, 4-<i>fppy =</i> 2-(4-fluorophenyl)­pyridinato-C²,N, acac = acetylacetonate) complexes were prepared and characterized. While <b>1</b> exhibits a phosphorescence band centered at 531 nm, which is red-shifted compared to that of unsubstituted (<i>ppy</i>)₂Ir­(acac) (<b>3</b>) (λ_em = 516 nm), the emission spectrum of <b>2</b> shows a blue-shifted band at 503 nm. Comparison with the emission band for the 4-fluoro-substituted <b>4</b> (λ_em = 493 nm) indicates a substantial bathochromic shift in <b>1</b>. Electrochemical and theoretical studies suggest that while carborane substitution on the 4-position of the phenyl ring lowers the ³MLCT energy by a large contribution to lowest unoccupied molecular orbital (LUMO) delocalization, which in turn assigns the lowest triplet state of <b>1</b> as [d_π(Ir)→π*­(<i>C</i>^∧<i>N</i>)] ³MLCT in character, the substitution on the 5-position raises the ³MLCT energy by the effective stabilization of the highest occupied molecular orbital (HOMO) level because of the strong inductive effect of carborane. An electroluminescent device incorporating <b>1</b> as an emitter displayed overall good performance in terms of external quantum efficiency (6.6%) and power efficiency (10.7 lm/W) with green phosphorescence

Phosphorescence Color Tuning of Cyclometalated Iridium Complexes by <i>o</i>‑Carborane Substitution

Heteroleptic (<i>C</i>^∧<i>N</i>)₂Ir­(acac) (<i>C</i>^∧<i>N</i> = 4-<i>CBppy</i> (<b>1</b>); 5-<i>CBppy</i> (<b>2</b>), 4-<i>fppy</i> (<b>4</b>) <i>CB</i> = <i>ortho</i>-methylcarborane; <i>ppy</i> = 2-phenylpyridinato-C²,N, 4-<i>fppy =</i> 2-(4-fluorophenyl)­pyridinato-C²,N, acac = acetylacetonate) complexes were prepared and characterized. While <b>1</b> exhibits a phosphorescence band centered at 531 nm, which is red-shifted compared to that of unsubstituted (<i>ppy</i>)₂Ir­(acac) (<b>3</b>) (λ_em = 516 nm), the emission spectrum of <b>2</b> shows a blue-shifted band at 503 nm. Comparison with the emission band for the 4-fluoro-substituted <b>4</b> (λ_em = 493 nm) indicates a substantial bathochromic shift in <b>1</b>. Electrochemical and theoretical studies suggest that while carborane substitution on the 4-position of the phenyl ring lowers the ³MLCT energy by a large contribution to lowest unoccupied molecular orbital (LUMO) delocalization, which in turn assigns the lowest triplet state of <b>1</b> as [d_π(Ir)→π*­(<i>C</i>^∧<i>N</i>)] ³MLCT in character, the substitution on the 5-position raises the ³MLCT energy by the effective stabilization of the highest occupied molecular orbital (HOMO) level because of the strong inductive effect of carborane. An electroluminescent device incorporating <b>1</b> as an emitter displayed overall good performance in terms of external quantum efficiency (6.6%) and power efficiency (10.7 lm/W) with green phosphorescence

OFF–ON Fluorescence Sensing of Fluoride by Donor–Antimony(V) Lewis Acids

A series of triarylmethylstibonium Lewis acids of general formula [Ph₂MeSb-(<i>p</i>-(C₆H₄))-FLUO]⁺ bearing a peripheral electron-rich fluorophore (FLUO = 10<i>H</i>-phenoxazine ([<b>3a</b>]⁺), diphenylamine ([<b>3b</b>]⁺), and 9<i>H</i>-carbazole ([<b>3c</b>]⁺)) have been synthesized and investigated for the fluorescence turn-on sensing of fluoride anions. Treatment of the stibonium cations with fluoride anions leads to the corresponding fluorostiboranes (<b>3a</b>-F–<b>3c</b>-F). While the stibonium cations are almost nonemissive, the fluorostiboranes display fluorophore-centered emissions arising from the corresponding π–π* excited state. The carbazole-containing derivative [<b>3c</b>]⁺ exhibits the most intense fluorescence turn-on response. It also displays a high binding constant (<i>K</i> > 10⁷ M^–1) in MeCN and shows compatibility with protic media such as MeOH (<i>K</i> = 950(±50) M^–1). Computational studies aimed at identifying the origin of the turn-on response show that the excited state of the stibonium cations is best described as charge transfer in nature with the π system of the fluorophore acting as the donor and the π*−σ* system of the stibonium unit acting as the acceptor. This π­(FLUO)−π*/σ*­(Ph₂MeSb-(<i>p</i>-(C₆H₄))) excited state is nonemissive, making these cations dark in the absence of fluoride anions. Conversion to the fluorostiboranes occurs via donation of a fluoride lone pair into the antimony-centered σ*. Formation of this Sb–F bond modifies the electronic structure of the platform and restores the emissive π–π* excited state of the fluorophore, thus accounting for the observed OFF–ON fluorescence response