Inorganic Chemistry最新文献

One-dimensional (1D) perovskites (perovskitoids) occupy an important place among modern semiconducting materials, offering design flexibility together with a wide range of properties. However, most such materials have a large bandgap, which limits their application in photovoltaics. Here, we present a new 1D hybrid perovskite containing the functional cation aminophenyl viologen (APhV). Similar to other materials from the viologen perovskite family, aminophenyl viologen iodidoplumbate(II) (APhV[Pb₂I₆]·2NMP) exhibits a broad absorption with a narrow and direct bandgap of 1.66 eV, which was calculated from the experimental data and is supported also by our first-principles simulations. Close contact between electron-rich inorganic chains and electron-accepting viologen molecules suggests charge transfer within the hybrid, which is also visible in the density of states. Considering its reasonable thermal stability, aminophenyl viologen iodidoplumbate can find a wide application in photovoltaics.

A new concept for obtaining cationic complexes with triflate counteranions from coordinating triflato ligands was developed. Various routes are leading to titanium(IV) and titanium(III) triflato complexes efficiently. The reactions of pentafulvene titanium complexes with either triflic acid or silver triflate give the corresponding titanium(IV) triflato complexes in excellent yields. Hydrolysis of the titanium(IV) bistriflato complexes leads to cationic aqua complexes via displacement of the triflato ligand, which consequently acts as a noncoordinating anion. A functionalized titanium(IV) monotriflato complex was synthesized by insertion of a nitrile into the Ti-C bond and the triflato ligand was displaced by an NHC. While the titanium(IV) complexes are mostly inert toward substrates, the donor-free titanium(III) triflato complex is a strong Lewis acid and forms various adducts with monodentate Lewis bases. The titanium(III) complex was oxidized by reaction with TEMPO, resulting in a diamagnetic titanium(IV) complex. The reaction with bidentate ligands results in cationic titanium(III) complexes due to displacement of the triflato ligand by the bidentate ligands. Treatment with acetone leads to an aldol reaction of two acetone molecules and the formation of a cationic diacetone alcohol complex.

The development of heterogeneous catalysts with abundant active sites is pivotal for enhancing the efficiency of photothermal CO₂ conversion. Herein, we report the construction of Co₂N_0.67@ZIF-67 through the in situ pyrolysis of ZIF-67 under low-temperature pyrolysis conditions. During the pyrolysis process, the crystal structure of ZIF-67 is predominantly preserved concurrently with the formation of Co₂N_0.67 nanoparticles (NPs) within the ZIF-67 pores. The optimal catalyst Co₂N_0.67@ZIF-67(450,2) not only possesses high photothermal efficiency but also can efficiently activate CO₂. Benefiting from these characteristics, Co₂N_0.67@ZIF-67(450,2) exhibited significant catalytic activity in the photocatalytic cycloaddition of CO₂ and epichlorohydrin. The yield of (chloromethyl)ethylene carbonate reached 95%, which is more than 4 times higher than that of ZIF-67 under visible light irradiation (300 W·m² Xe lamp, 3 h). This study could offer an alternative approach to enhance the photocatalytic activity of MOFs through low-temperature pyrolysis.

Ionic plastic crystals (IPCs), characterized by nearly spherical molecular ions, exhibit remarkable solid-state characteristics including high ionic conductivity. However, most IPCs are organic onium salts. Incorporating organometallic half-sandwich complexes into IPCs is challenging owing to their low-symmetry structures. This paper introduces a novel series of IPCs composed of salts derived from half-sandwich organometallic complexes. We synthesized five salts of [Ru(Cp)(tmeda)(CO)]X (tmeda = N,N,N',N'-tetramethyl-1,2-ethanediamine, X = anion) with different anions and examined their phase behavior, crystal structures, and molecular motion in the solid-state. Salts featuring the CPFSA (= 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide), B(CN)₄^-, and FSA^- (= (FSO₂)₂N^-) anions underwent phase transitions to an IPC phase with a CsCl-type structure in the temperature range of 327-364 K. Employing smaller anions led to an increase in the transition temperature. In each salt, the coordination number, representing the number of anions surrounding one cation, remained eight in IPC and low-temperature phases. However, salts containing smaller anions (CF₃BF₃^- and PF₆^-) displayed a rotator phase rather than the IPC phase. In these cases, the coordination numbers were six at low temperatures.

Nonlinear optical (NLO) coherent light sources are widely applied in many areas of science and technology. As the core medium, the NLO material is required to have a wide transparent range, a large NLO response, and a high laser damaged threshold (LDT). It is common knowledge that langasite (La₃Ga₅SiO₁₄, LGS) crystal has an underdeveloped second-harmonic generation (SHG) coefficient and a small birefringence, which seriously restrict its application in the NLO field, despite that it has a broad transmittance spectrum and a moderate LDT. Herein, we have successfully obtained novel langasite NLO crystals LGSS (La₃Ga₅Si_0.5Sn_0.5O₁₄) and LGGS (La₃Ga₅Ge_0.5Sn_0.5O₁₄), with short UV absorption edges of 209 and 212 nm, respectively. Incorporating heavy ions Sn⁴⁺ into the structure, a distorted BO₆ octahedron was adjusted by the radius difference between Sn⁴⁺ and Si⁴⁺/Ge⁴⁺, which caused the strong SHG responses in LGSS (∼10.77 × KDP) and LGGS (∼9.23 × KDP) and increased birefringences of 0.034 and 0.025, respectively. Besides, they also had large energy band gaps (4.95 eV for LGSS, and 4.93 eV for LGGS), which allowed high LDTs with LGSS of 1.3 GW/cm² and LGGS of 813 MW/cm². This work demonstrates a new strategy to enhance SHG responses and birefringence for existing NLO materials and enriches langasite family crystals.

Optimizing the electronic configuration improved the electrocatalytic performance of Ru doping. However, efficiently doping Ru and ensuring its stability in the hollow hierarchical structure posed a challenge. This work innovatively utilized the huge temperature difference between calcination and ice water (0 °C) to rapidly dope Ru atoms onto the CoNiP hierarchical spheres. Notably, the Ru-anchored hierarchical spheres enhanced the active area and internal space utilization. In addition, the addition of Ru dopant optimized the electronic structure and hydrogen evolution reaction (HER) kinetics of CoNiP. Surprisingly, Ru-CoNiP only required 250 mV to generate 1 A cm^-2, which was 1.5 times that of commercial Pt/C. Moreover, its activation energy (E_a) was 24.3% lower than CoNiP, further confirming that the Ru dopant reduced the energy barrier of alkaline HER. In conclusion, this work proposed a new method for promoting the doping of trace amounts of ruthenium into hierarchical spheres through quenching.

The Na_xMnO₂ system is an important class of materials with potential applications in rechargeable batteries, supercapacitors, catalysts, and gas sensors. This work reports the synthesis of Na_xMnO₂ (x = 0.39, 0.44, 0.48, 0.66, and 0.70) compounds and their characterization by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and impedance spectroscopy (IS) techniques. The compounds in this series exhibit a significant variation in their structures with the extent of Na-content. The change in the nature of bonding with increasing Na content was investigated, and its effect on material stability as well as electrotransport properties was investigated. A detailed thermodynamic evaluation of these materials was carried out employing calorimetric techniques, and the data were correlated with changes in the chemical environment around the Na ion. This analysis is crucial for predicting the thermodynamic stability of Na_xMnO₂ compounds under different environments for their applications in Na-ion batteries.

Currently, optical thermometry has received widespread attention because of its noncontact and wide temperature range, but most of them are based on the application of dual-band optical ratiometric thermometry, so the development of a single-band ratiometric (SBR) optical thermometry, which is easier to analyze and use, is particularly important. In this work, the position of the intervalence charge-transfer (IVCT) band for Na₂Gd_2-xLa_xTi₃O₁₀:Pr³⁺ (x = 0, 0.5, 1.0, 1.5, 2.0) was modulated using Gd/La substitution, enhancing the thermal response difference of Pr^{3+ 1}D₂ → ³H₄ under charge-transfer band (CTB) and IVCT band excitation, thereby achieving high-sensitivity SBR optical thermometry, and the maximum relative sensitivity (S_r-max) reached 2.95% (at 298 K). In addition, this series of phosphors has high-color-purity red emission, indicating that it has potential for multifield applications.

Nonstoichiometric lead oxides play a key role in the formation and cycling of the positive electrodes in a lead acid battery. These phases have been linked to the underutilization of the positive active material but also play a key role in the battery's cycle life, providing interparticle adhesion and the connection to the underlying lead grid. Similar phases have previously been identified by mass loss or color change during thermal annealing of PbO₂ to PbO, suggesting that at least two intermediate PbO_x phases exist. Using multiple, in situ analysis techniques (powder diffraction, X-ray absorption, X-ray photoelectron spectroscopy) and ex situ nuclear magnetic resonance measurements, the structural conversion and changes in the lead oxidation state were identified during this process. Isolation of the PbO_x phases enabled confirmation of Pb₃O₅ and Pb₂O₃ by diffraction and the first ²⁰⁷Pb NMR measurement of these intermediates. The thermodynamic and kinetic stability of these intermediates and other reported polymorphs were determined by density functional theory, providing key insight into their origins and variation of PbO_x structures found in previous studies.

Zintl phases have potential applications as thermoelectric materials for power generation and cooling owing to their complex crystal structures and unique electronic properties. We carried out reactions of silicon with barium and strontium in excess Mg/Zn flux to synthesize (Ba/Sr)_5+xMg_19-xSi₁₂ Zintl phases, investigating the effect of varying Ba/Sr ratio on site mixing and thermoelectric properties. (Ba/Sr)_5+xMg_19-xSi₁₂ compounds with 0 < x < 3 are charge-balanced Zintl phases which adopt the hexagonal Ho₅Ni₁₉P₁₂ structure type (space group P6̅2m). Density of states calculations indicate that these materials are semimetals. Single-crystal X-ray diffraction data and elemental analysis for Ba₅Mg₁₉Si₁₂, Ba_4.86Sr_2.94Mg_16.20Si₁₂, Ba_3.63Sr_4.20Mg_16.17Si₁₂, Ba_1.93Sr_5.99Mg_16.08Si₁₂, and Sr_7.82Mg_16.18Si₁₂ show occupation of barium and strontium cations in Ho sites, while strontium mixes with magnesium on a specific Ni site. Powder XRD data of products show that they are single phase throughout the sample. Thermoelectric measurements indicate that increasing strontium content and mixing on three cation sites decreases thermal conductivity; it is hypothesized that improved overall thermoelectric behavior is likely due to the rattling of the Sr cations in their positions.