Phenanthroline-Mediated Photoelectrical Enhancement in Calix[4]arene-Functionalized Titanium-Oxo Clusters.

Incorporating two organic ligands with different functionalities into a titanium-oxo cluster entity simultaneously can endow the material with their respective properties and provide synergistic performance enhancement, which is of great significance for enriching the structure and properties of titanium-oxo clusters (TOCs). However, the synthesis of such TOCs is highly challenging. In this work, we successfully synthesized a TBC4A-functionalized TOC, [Ti2(TBC4A)2(MeO)2] (Ti2; MeOH = methanol, TBC4A = tert-butylcalix[4]arene). By adjusting the solvent system, we successfully introduced 1,10-phenanthroline (Phen) and prepared TBC4A and Phen co-protected [Ti2(TBC4A)2(Phen)2] (Ti2-Phen). Moreover, when Phen was replaced with bulky 4,7-diphenyl-1,10-phenanthroline (Bphen), [Ti2(TBC4A)2(Bphen)2] (Ti2-Bphen), which is isostructural with Ti2-Phen, was obtained, demonstrating the generality of the synthetic method. Remarkably, Ti2-Phen demonstrates good stability and stronger light absorption, as well as superior photoelectric performance compared to Ti2. Density functional theory (DFT) calculations reveal that there exists ligand-to-core charge transfer (LCCT) in Ti2, while an unusual ligand-to-ligand charge transfer (LLCT) is present in Ti2-Phen, accompanied by partial LCCT. Therefore, the superior light absorption and photoelectric properties of Ti2-Phen are attributed to the existence of the unusual LLCT phenomenon. This study not only deeply explores the influence of Phen on the performance of the material but also provides a reference for the preparation of materials with excellent photoelectric performance.

Solid-State Synthesis of Aluminophosphate Zeotypes by Calcination of Amorphous Precursors.

Because of the growing interest in the applications of zeolitic materials and the various challenges associated with traditional synthesis methods, the development of novel synthesis approaches remains of fundamental importance. Herein, we report a general route for the synthesis of aluminophosphate (AlPO) zeotypes by simple calcination of amorphous precursors at moderate temperatures (250-450 °C) for short reaction times (3-60 min). Accordingly, highly crystalline AlPO zeotypes with various topologies of AST, SOD, LTA, AEL, AFI, and -CLO, ranging from ultra-small to extra-large pores, have been successfully synthesized. Multinuclear multidimensional solid-state NMR techniques combined with complementary operando mass spectrometry (MS), powder X-ray diffraction, high-resolution transmission electron microscopy, and Raman characterizations reveal that covalently bonded fluoride in the intermediates catalyze the bond breaking and remaking processes. The confined organic structure-directing agents with high thermal stability direct the ordered rearrangement. This novel synthesis strategy not only shows excellent synthesis efficiency in terms of a simple synthesis procedure, a fast crystallization rate, and a high product yield, but also sheds new light on the crystallization mechanism of zeolitic materials.

Synthesis and Crystal Structure of a New RTH-Type Precursor and Its Interlayer Expanded Zeolite.

Two dimensional zeolites have drawn a lot of attention due to their structural diversity and chemical composition, which can be used to obtain 3D zeolites, for which there is no direct synthesis. Here, a new layer silicate zeolite L was synthesized using the N, N-dimethyl-(2-methyl)-benzimidazolium as the organic structure-directing agent (OSDA) in the presence of fluoride. Structure determination by single-crystal X-ray diffraction reveals that the pure silica precursor with five-ring pores in the crystalline sheets is composed of the rth layer stacking along the (001) direction in an …AAAA… sequence with SDA+ cations and F- residing within the interlayer spaces. Variable temperature powder X-ray diffraction (PXRD) results showed that the new layer could transform into a 3D RTH topology structure at 350 °C via 2D-3D topotactic transformation. Furthermore, a new 3D zeolite material is obtained by treating the original layer with a diethoxydimethylsilane agent under hydrochloric acid condition (HCl-DEDMS). Based on the PXRD results and the original layer structure, the new 3D zeolite structure expanding the rth layer with another Si atom is constructed, which possesses a 10×8×6 channel system. It displays a high BET surface area of 188 cm3 /g with an external surface area of 130 cm3 /g. The structure and textural properties pave a way for potential catalytic applications. The research not only provides a new layered zeolite, broadening the 2D zeolite framework types, but also allows for the discovery of a new stable 3D zeolite expanding the RTH structure with Si atom, which hasn't been reported yet.

Li-Mn Bimetallic Metal-Organic Framework and Its Derivative as a Cathode for Lithium-Ion Batteries.

The bimetallic organic-inorganic hybrid complex [Li2Mn3(ipa)4(DMF)4]n (ipa = deprotonated 1,3-isophthalic acid, DMF = N,N'-dimethyl formamide) was synthesized via a solvothermal method and then further calcined at high temperature to prepare a spinel-type lithium manganate (LiMn2O4) cathode under different atmospheres with various calcination conditions. The structure of the complex [Li2Mn3(ipa)4(DMF)4]n was represented by single-crystal X-ray diffraction (XRD), powder XRD, and thermogravimetric (TG) analysis. The morphology and elements of LiMn2O4 were analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of LiMn2O4 indicated that the direct calcination in an air atmosphere at 850 °C for 12 h was the optimal synthetic condition. The initial discharge specific capacity can reach 95.9 mA h g-1 with an open-circuit voltage of ca. 3.0 V and an upper cutoff voltage of ca. 4.3 V at 0.1 C. The initial discharge-specific capacity of 89.8 mA h g-1 at 1 C had a Coulombic efficiency of 95.3%. This was 73 mA h g-1 at a high rate of 5 C increasing to 91.6 mA h g-1 after returning to 0.1 C. After 500 cycles at 1 C, the system remained at 80.7 mA h g-1 with 89.9% of the initial discharge specific capacity. These features exhibit better stability than that of the reported LiCoO2 and LiNiO2 in battery material for LiMn2O4 enforcement.

Morphology Regulation of Zeolite MWW via Classical/Nonclassical Crystallization Pathways.

The morphology and porosity of zeolites have an important effect on adsorption and catalytic performance. In the work, simple inorganic salts, i.e., Na salts were used to synthesize MWW zeolite using the organic compound 1-Butyl-2,3-dimethyl-1H-imidazol-3-ium hydroxide as a structure-directing agent and the morphology was regulated by the alkali metals. The sample synthesized without Na salts shows a dense hexagon morphology, while different morphologies like ellipsoid, wool ball, and uniform hexagon appear when using NaOH, Na2CO3, and NaHCO3, respectively. Moreover, the impact of Na salts on the induction, nucleation, and the evolution of crystal growth was studied. Different kinds of Na salts have a different impact on the crystalline induction time in the order of NaHCO3 (36 h) < Na2CO3 (72 h) = NaOH (72 h). Meanwhile, the crystalline mechanism with the cooperation of inorganic salts and the organic SDAs is proposed. NaOH- and Na2CO3-MWW zeolite crystallized with a network of hydrogel via the nonclassical pathway in the system; however, the product is synthesized via a classical route in the NaHCO3 environment. This work provides information about MWW zeolite crystallization and modulating diverse morphologies by adjusting the process.

Synthesis and Characterization of A Stable Extra-Large-Pore Zeolite with 15×12×12 Member-Ring Channels.

Extra-large-pore zeolites have great application potential in various industrial fields, such as oil refinery, fine chemicals and biomass processing. Herein, we report the synthesis of an extra-large-pore germanosilicate zeolite (named NUD-13) by using an easily obtained aromatic organic cation 1,2-dimethyl-3-propyl-benzimidazolium as organic structure-directing agents. NUD-13 possesses a rare 15-member ring extra-large-pore channel intersecting with two elliptical 12-member ring channels, which is isostructural to germanosilicate zeolite GeZA synthesized by using triphenylsulfonium. The germanium in NUD-13 can be partially substituted by acid treatment to obtain stable high silica zeolite. In addition, aluminium is added into the framework of NUD-13 during the post-synthesis treatment process, which provides a foundation for catalytic application.

Direct Synthesis of An Aluminosilicate POS Zeolite with Intersecting 12×11×11-Member-Ring Pore Channels by Using a Designed Organic Structure-Directing Agent.

Large and extra-large pore zeolites have been widely applied in industrial areas as catalysts, adsorbents, etc. Among them, silica and/or aluminosilicate zeolites have been attracted great attention due to their excellent hydrothermal stability and strong acidity. However, a great deal of zeolite structures are still not available in the form of silica and/or aluminosilicate. Herein, we report the synthesis of pure silica and aluminosilicate large-pore zeolites, denoted as NUD-14 and Al-NUD-14, respectively, by using a designed cation 1-ethyl-4-phenylpyridinium as an organic structure-directing agent (OSDA). NUD-14 has an intersecting 12×11×11-member ring pore system, which is isostructural to the germanosilicate PUK-16 zeolite with a POS topology. The OSDAs can be completely removed from the framework by calcination. NUD-14 and Al-NUD-14 possess excellent acid and hydrothermal stabilities, superior to the germanosilicate POS zeolite. The incorporation of Al into the zeolite framework makes the Al-NUD-14 zeolite possess medium and strong acidities. The successful synthesis of NUD-14 consisting of a rare odd-member ring pore structure may provide a platform for interesting size- and shape-selective catalytic applications.

Synthesis, Structure and Properties of an Extra-Large-Pore Aluminosilicate Zeolite NUD-6.

Pure silica zeolites possessing uniform micropores, large surface area and high thermal and chemical stability have been widely studied and used in the fields of fine chemicals and oil industry. The incorporation of aluminium into the framework of silica zeolites changes their properties, making them more industrially useful as adsorbents and catalysts. Herein, we report the synthesis and characterization of an extra-large-pore aluminosilicate zeolite NUD-6 with a 16-membered-ring pore channel. Aluminium was directly incorporated into the zeolite NUD-6 framework, as confirmed by 27 Al MAS NMR studies and ammonia temperature-programmed desorption probes. Al-NUD-6 was not stable when heated at 550 °C to remove the organic templates. However, the organic templates in Al-NUD-6 could be removed by oxidation in nitric acid at room temperature. The obtained Al-NUD-6H retained the crystalline structure and possessed both micropores and mesopores despite the occurrence of severe structural distortions due to the presence of the corner-sharing Q3 Si2 O7 units. The incorporation of aluminium resulted in both medium and strong acid sites in Al-NUD-6H, and could facilitate its use in adsorption and catalysis.

An Extra-Large-Pore Pure Silica Zeolite with 16×8×8-Membered Ring Pore Channels Synthesized using an Aromatic Organic Directing Agent.

Extra-large-pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra-large-pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra-large-pore silica zeolite, designated NUD-6, by using an easily synthesized aromatic organic cation as structure-directing agent. NUD-6 possesses an intersecting 16×8×8-membered ring pore channel system constructed by four-connected (Q4 ) and unusual three-connected (Q3 ) silicon species. The organic cations in NUD-6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD-6 presents a feasible means to prepare extra-large pore silica zeolites by using assembled aromatic organic cations as structure-directing agents.

Solution Synthesis of Porous Silicon Particles as an Anode Material for Lithium Ion Batteries.

Nanostructured silicon-based materials with porous structures have recently been found to be impressive anode materials with high capacity and cycling performance for lithium-ion batteries. However, the current methods of preparing porous silicon have generally been confronted with the requirement for multiple steps and complex synthesis. In the present study, porous silicon with high surface area was prepared by using a high yielding and simple reaction in which commercial magnesium powder readily reacts with HSiCl3 with the help of an amine catalyst under mild conditions. The obtained porous silicon was coated with a nitrogen-doped carbon layer and used as the anode for lithium-ion batteries. The porous Si-carbon nanocomposites exhibited excellent cycling performance with a retained discharge capacity of 1300 mA h g-1 after 200 cycles at 1 A g-1 and a discharge capacity of 750 mA h g-1 at a current density of 2 A g-1 after 250 cycles. Remarkably, the Coulombic efficiency was maintained at nearly 100 % throughout the measurements.

Size-tailored synthesis and luminescent properties of three-dimensional BaMoO4 , BaMoO4 :Eu(3+) micron-octahedrons and micron-flowers via sonochemical route.

Almost monodisperse three-dimensional (3D) BaMoO4, BaMoO4 :Eu(3+) micron-octahedrons and micron-flowers were successfully prepared via a large-scale and facile sonochemical route without using any catalysts or templates. X-Ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersion X-ray (EDS), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy were employed to characterize the as-obtained products. It was found that size modulation could be easily realized by changing the concentrations of reactants and the pH value of precursors. The formation mechanism for micron-octahedrons and micron-flowers was proposed on the basis of time-dependent experiments. Using excitation wavelengths of 396 or 466 nm for BaMoO4 :Eu(3+) phosphors, an intense emission line at 614 nm was observed. These phosphors might be promising components with possible application in the fields of near UV- and blue-excited white light-emitting diodes. Simultaneously, this novel and efficient pathway could open new opportunities for further investigating the properties of molybdate materials.

Photoluminescence properties and energy transfer in Ce(3+) /Dy(3+) co-doped Sr(3) MgSi(2) O(8) phosphors for potential application in ultraviolet white light-emitting diodes.

Sr(3) MgSi(2) O(8) :Ce(3+) , Dy(3+) phosphors were prepared by a solid-state reaction technique and the photoluminescence properties were investigated. The emission spectra show not only a band due to Ce(3+) ions (403 nm) but also as a band due to Dy(3+) ions (480, 575 nm) (UV light excitation). The photoluminescence properties reveal that effective energy transfer occurs in Ce(3+) /Dy(3+) co-doped Sr(3) MgSi(2) O(8)phosphors, and the co-doping of Ce(3+) could enhance the emission intensity of Dy(3+) to a certain extent by transferring its energy to Dy(3+) . The Ce(3+) /Dy(3+) energy transfer was investigated by emission/excitation spectra, and photoluminescence decay behaviors. In Sr2.94 MgSi2 O8 :0.01Ce(3+) , 0.05Dy(3+) phosphors, the fluorescence lifetime of Dy(3+) (from 3.35 to 27.59 ns) is increased whereas that of Ce(3+) is greatly decreased (from 43.59 to 13.55 ns), and this provides indirect evidence of the Ce(3+) to Dy(3+) energy transfer. The varied emitted color of Sr(3) MgSi(2) O(8):Ce(3+) , Dy(3+) phosphors from blue to white were achieved by altering the concentration ratio of Ce(3+) and Dy(3+) . These results indicate Sr(3) MgSi(2) O(8):Ce(3+) , Dy(3+) may be as a candidate phosphor for white light-emitting diodes.

Two-dimensional rare-earth-metal coordination polymers based on biphenyl-3,3',5,5'-tetracarboxylic acid displaying luminescence.

Two coordination polymers were rationally designed and successfully constructed using the rigid multicarboxylic acid ligand biphenyl-3,3',5,5'-tetracarboxylic acid (H4BPTC) and rare earth metal ions (Eu3+ and Ho3+) under solvothermal conditions. The compounds are poly[[tetra-µ2-acetato-bis(µ6-biphenyl-3,3',5,5'-tetracarboxylato)tetrakis(dimethylacetamide)tetraeuropium(III)] dimethylacetamide disolvate dihydrate], {[Eu4(C16H6O8)2(C2H3O2)4(C4H9NO)4]·2C4H9NO·2H2O}n, and poly[[tetra-µ2-acetato-bis(µ6-biphenyl-3,3',5,5'-tetracarboxylato)tetrakis(dimethylacetamide)tetraholmium(III)] pentahydrate], {[Ho4(C16H6O8)2(C2H3O2)4(C4H9NO)4]·5H2O}n, Single-crystal X-ray diffraction analysis reveals that both polymers possess a two-dimensional structure and they also display good thermal stability up to ca 280 °C and photoluminescence with an orange-red light emission.

Synthesis and characterization of a layered aluminosilicate NUD-11 and its transformation to a 3D stable zeolite.

Aluminosilicate zeolites are a well-known class of crystalline materials that have wide applications in various industrial fields due to their selective adsorption, acidic sites, and stable hydrothermal stability. Great efforts have been devoted to discovering new zeolite structures. As one of the effective methods, layered silicates have been used as precursors to produce stable zeolites through topotactic transformation. Herein, a new layered aluminosilicate, named NUD-11, was hydrothermally synthesized using N,N-dimethylbenzimidazolium as the structure directing agent (SDA). It was then converted into a stable crystalline zeolite by linking the interlayer Si-OH groups with a silylation agent, diethoxymethylsilane. Studies showed that the resulting NUD-11S consisted of alkylsilicate -O-Si(CH3)2-O- linkages between the adjacent layers to form interconnecting 10- and 12-membered ring channels. The calcined NUD-11S possessed micropores of 0.74 nm and 1.2 nm in diameter with a large specific surface area of 314 m2 g-1. The abundant microporosity would make NUD-11S useful as adsorbents or catalysts.

Ionothermal Synthesis of Crystalline Nanoporous Silicon and Its Use as Anode Materials in Lithium-Ion Batteries.

Silicon has great potential as an anode material for high-performance lithium-ion batteries (LIBs). This work reports a facile, high-yield, and scalable approach to prepare nanoporous silicon, in which commercial magnesium silicide (Mg2Si) reacted with the acidic ionic liquid at 100 °C and ambient pressure. The obtained silicon consists of a crystalline, porous structure with a BET surface area of 450 m2/g and pore size of 1.27 nm. When coated with the nitrogen-doped carbon layer and applied as LIB anode, the obtained nanoporous silicon-carbon composites exhibit a high initial Coulombic efficiency of 72.9% and possess a specific capacity of 1000 mA h g-1 at 1 A g-1 after 100 cycles. This preparation method does not involve high temperature and pressure vessels and can be easily applied for mass production of nanoporous silicon materials for lithium-ion battery or for other applications.

Facile Solution Synthesis of Red Phosphorus Nanoparticles for Lithium Ion Battery Anodes.

Red phosphorus (RP) has attracted extensive attention as an anodic material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity of 2596 mA h g- 1 and earth abundance. However, the facile and large-scale preparation of the red phosphorus nanomaterials via a solution synthesis remains a challenge. Herein, we develop a simple and facile solution method to prepare red phosphorus nanoparticles (RP NPs). PCl3 readily reacts with HSiCl3 in the presence of amines at room temperature to produce amorphous RP NPs with sizes about 100-200 nm in high yields. When used as an anode for rechargeable lithium ion battery, the RP NP electrode exhibits good electrochemical performance with a reversible capacity of 1380 mA h g- 1 after 100 cycles at a current density of 100 mA g- 1, and Coulombic efficiencies reaching almost 100% for each cycle. The study shows that this solution synthesis is a facile and convenient approach for large-scale production of RP NP materials for use in high-performance Li-ion batteries.