Inorganic Chemistry最新文献

A methodology to access Z-1-silyl-2-aluminyl-disubstituted olefins is developed. It relies on the uncatalyzed ring opening of silacyclopropenes in the presence of a stoichiometric amount of trimethylaluminum. The resulting heterosubstituted alkenes exhibit a particular interaction between the electron-rich [Si-CH₃] moiety and the electron-deficient diorganoaluminyl group, resulting in similar geometrical features due to the proximity of these two centers. This interaction is rationalized using experimental and theoretical descriptors. The regioselectivity and functional tolerance of the methylalumination were also studied in the case of unsymmetrical silacyclopropenes, and the methodology ultimately transposed to the synthesis of a polymeric organoalane incorporating tricoordinated aluminum centers.

A novel heterometallic trinuclear cluster [Cu^II₂Mn^II(cpdp)(NO₃)₂(Cl)] (1) has been designed and synthesized by employing a molecular library approach that uses CuCl₂·2H₂O and Mn(NO₃)₂·4H₂O as inorganic metal salts and H₃cpdp as a multifunctional organic scaffold (H₃cpdp = N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol). This heterometallic cluster has emerged as an unusual ferromagnetic material and promising electrocatalyst for hydrogen evolution reaction (HER) in the domain of inorganic and materials chemistry. Crystal structure analysis establishes the structural arrangement of 1, revealing a butterfly-like topology with an unusual seven-coordinated Mn(II) center. Formation of this cluster is accomplished by a self-assembly process through functionalization of 1 with one μ₂:η¹:η¹-nitrate and two μ₂:η²:η¹-benzoate groups via the Cu^II(μ₂-NO₃)Cu^II} and {Cu^II(μ₂-O₂CC₆H₅)Mn^II} linkages, respectively. Variable-temperature SQUID magnetometry revealed the coexistence of ferromagnetic and antiferromagnetic interactions in 1. The observed magnetic behavior in 1 is unexpected because of a large Cu-O-Mn angle with a value of 132.05°, indicating that the correlation between coupling constants and the structural parameters is a multifactor problem. This cluster shows excellent electrocatalytic performance for the HER attaining a current density of 10 mA/cm² with a Tafel slope of 183 mV dec^-1 at a 310 mV overpotential value. Essentially, cluster 1 shows exceptional electrochemical stability at ambient temperature, accompanied by minimal degradation of the current density as examined by chronoamperometric studies. Density functional theory calculations establish the mechanistic insight into the HER process, indicating that the Cu^II-OCO-Mn^II site is the active site for formation of molecular hydrogen.

CuIn(S_xSe_1-x)₂ nanocrystals as an emerging class of functional materials present huge potential for industrial applications; however, the synthesis of CuIn(S_xSe_1-x)₂ nanocrystals remains a formidable challenge in achieving both tunable band gap and phase. Here, we reported a facile hot-injection method for synthesizing a family of wurtzite CuIn(S_xSe_1-x)₂ nanocrystals, enabling manipulation of the S and Se contents across the entire compositional range (0 ≤ x ≤ 1). The obtained nanocrystals exhibit band gaps ranging from 1.21 to 1.58 eV, which vary depending on the S/Se ratios in the products. This approach can be readily extended to other scenarios involving chalcogenide nanomaterials, thereby facilitating the advancement of next-generation functional materials and applications.

Oxychalcogenides are receiving increasing interest as nonlinear-optical (NLO) materials because of the possible combination of advantages from oxides and chalcogenides. Here, two new pentanary oxythiogermanates Eu₂MGe₂OS₆ [M = Zn (1), Cd (2)] were obtained by the facile metal oxide-boron-sulfur solid-state route. They crystallize with a melilite-type structure and feature {[MGe₂OS₆]^4-}_∞ layers built by Ge₂OS₆ dimers and MS₄ tetrahedra. Their optical band gaps are 2.37 and 2.38 eV. As the first NLO rare-earth (RE)/d¹⁰ dual-metal oxychalcogenides, they exhibit phase-matchable NLO responses and enhanced laser-induced damage thresholds. Theoretical calculations show that the NLO responses are predominantly contributed by the EuOS₇ motifs. This work provides the potential of RE/d¹⁰ dual-metal-based NLO materials.

Intercalation can be used to alter the electronic properties of graphitic materials. Intercalation is, however, a notoriously brute-force process typically carried out at a high temperature in an inert environment for an extended period. As an exception to this, a simple sonication-assisted intercalation of potassium into graphite at ambient room temperature (RT) has been reported. Here we extend this approach to intercalation of potassium into other carbon allotropes, including planar graphene nanoplatelets (GNPs) and curved graphitic tubes and shells, such as multiwalled carbon nanotubes (MWCNTs) and nanodiamond-derived carbon nano-onions (NCNOs). We report the rapid room-temperature sonication-assisted potassium metal intercalation of GNPs, MWCNTs, and NCNOs. Powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and electron dispersive X-ray spectroscopy (EDS) were used to visualize the location of potassium in the intercalated products.

As an important nonoil route for acquiring aromatics, the highly efficient conversion of methanol to aromatics over Zn/ZSM-5 zeolites remains an ongoing challenge. In this work, we developed a uniform loading approach of zinc and further combined it with a hollow capsule structure to design the high-performance Zn/ZSM-5 catalyst. The electrostatic assembly among EDTA^3-, n-butylamine⁺ and negative silica-alumina gel gave rise to an "Inorganic-Organic Hybrid Sphere" in form of Na_{(l+m+n+3x)-(y+z)}·{[(SiO)₄Al^-]_l/(SiO^-)_m(n-butylamine⁺)_y(EDTA^3-)_x(n-butylamine⁺)_z(SiO^-)_n, which further transformed into mesoporous aluminosilicates sphere (MASS) through calcination. The characteristic of abundant mesopore guaranteed MASS fantastic ability to evenly incorporate Zn ingredient inside, and the resultant Zn/MASS further served as a "hard template" for the direct synthesis of Hollow Zn/ZSM-5 capsules, rather than after impregnation. When tested in the methanol-to-aromatics (MTA) process, the direct synthesis method not only facilitated the homogeneous dispersion of the Zn ingredient, but also benefited for the generation of more (ZnOH)⁺ sites and strengthened their synergism with zeolite acid for the superior aromatics selectivity (50.63%). Meanwhile, the hollow capsule structure increased the contact time of MTA intermediate products with the Zn/ZSM-5 shell, and it increased the coke-admitting capacity and suppressed the coke rate, which maintained quite an excellent stability (131 h). Therefore, the above combination of hollow capsule structure and uniform load of Zn ingredient brings forward a wide prospect to develop zeolite materials with excellent properties in catalysis.

Reported are the synthesis and structural characterization of Cs₃LiGe₄, the first structurally characterized lithium-containing cesium germanide. Single-crystal X-ray diffraction data indicate that Cs₃LiGe₄ crystallizes in an orthorhombic crystal system with the space group Cmcm (no. 63, Person symbol oS32) with unit cell parameters a = 6.950(2) Å, b = 15.503(3) Å, and c = 9.919(2) Å and V = 1068.65(4) ų. The structure consists of [Ge]₄^4- tetrahedral clusters with the Li atoms positioned in such a way that polyanionic [LiGe]₄^3- chains could be considered as well. Electronic structure calculations indicate an intrinsic semiconductor with a band gap of 0.76 eV. To understand the nuances of the chemical bonding, position-space techniques based on the quantum theory of atoms in molecules, the electron localizability indicator, and their basin intersections were employed confirming the covalent character of the Ge-Ge bonding. The strong polarity of the interactions between [Ge]₄^4- and the surrounding lithium and cesium cations suggests to interpret these as mainly ionic, further supporting the most basic structure rationalization [Cs⁺]₃[Li⁺][Ge]₄^4-, following the Zintl-Klemm concept. The electron localizability indicator topology affirms the striking similarities between [Ge]₄^4- and molecular As₄ tetrahedra in yellow arsenic, further supporting Klemm's pseudoatom concept on a quantum chemical basis.

Multifunctional materials have long been a popular research area, with organic-inorganic hybrids frequently utilized due to their diverse properties and versatile assembly techniques. In this context, a novel Mn-based organic-inorganic hybrid compound (BTPA)₂MnBr₄(1) was prepared, with strong green photoluminescence, phase transition under thermal stimulation, and two reversible dielectric-state switches. This compound exhibits strong green photoluminescence under ultraviolet excitation, boasting a quantum yield of 44.36%. Furthermore, it demonstrates a reversible ferroelastic phase transition at 358/348 K. The integration of temperature and photosensitivity in compound 1 opens up new avenues for the development and exploration of a broader spectrum of multifunctional phase transition materials.

Catalytic applications of DNA duplexes containing Ag⁺-mediated cytosine-cytosine base pairs (C-Ag⁺-C) have not been well investigated. In this study, we demonstrate a novel approach for forming highly active DNA-capped Ag nanoparticle (DNA-AgNP) catalysts for the reduction of 4-nitrophenol (4-NP) using sodium borohydride (NaBH₄). This approach is based on the in situ generation of DNA-AgNPs from DNA duplexes containing C-Ag⁺-C (DNA duplex-Ag⁺). UV-vis spectroscopic analysis suggests that the DNA duplex-Ag⁺ complex acts as an excellent catalyst precursor for 4-NP reduction with NaBH₄. Transmission electron microscopy observations of the reaction solution after the 4-NP reduction reaction using DNA duplex-Ag⁺ provided detailed experimental insights into the mechanism of the catalytic activity of DNA duplex-Ag⁺ for 4-NP reduction. In the reaction solution, DNA-AgNPs were initially formed (DNA duplex-Ag⁺ + NaBH₄ → DNA-AgNPs) and then served as water-soluble catalysts for 4-NP reduction. Notably, the catalytic properties of the DNA-AgNPs generated in situ were affected by the DNA strand length and sequence. The properties of DNA duplex-Ag⁺ may provide a new application of DNA molecules containing metallobase pairs as water-soluble catalyst precursors.

Methane-propane coaromatization (MPCA) upgrades two abundant and inexpensive light alkanes into value-added aromatic products. While Ga-loaded MFI zeolites represent by far the most promising catalysts for MPCA reaction, they often contain a sizable portion of Ga species at the external surface of zeolites, which are remote from the Brønsted acid sites (BAS) within MFI pores and thus inefficient for MPCA. Here, we show that Ga can be introduced into MFI pores at fairly high loadings via a simple cocrystallization approach, yielding catalysts possessing well-dispersed Ga sites predominantly residing inside the pores and framework. Adjacency between Ga and BAS within the constraints of MFI channels makes these (Ga, Al)-H-MFI catalysts more active toward methane and propane activation and more selective toward aromatics compared to the Ga/MFI counterparts prepared by impregnation that inevitably leaves a large fraction of Ga at the external surface (i.e., without confinement and few adjacent BAS). Further, the effects of the Si/Al ratio on MPCA performance have been investigated for (Ga, Al)-H-MFI catalysts. Due to the multifold roles of BAS in the overall reaction sequence, an increased BAS concentration generally results in higher propane conversion and productivity of aromatics together with lower net methane conversion and severer coking.