Structure-direction towards the new large pore zeolite NUD-3.

The new zeolite NUD-3 possesses a three-dimensional system of large pore channels that is topologically identical to those of ITQ-21 and PKU-14. However, the three zeolites have distinctly different frameworks: a particular single 4-membered ring inside the denser portion of the zeolite is missing in PKU-14, disordered in ITQ-21 and fully ordered in NUD-3. We document these differences and use molecular simulations to unravel the mechanism by which a particular structure directing agent dication, 1,1'-(1,2-phenylenebis(methylene))bis(3-methylimidazolium), is able to orient this inner ring.

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.

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.

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.

Step-by-step assembly preparation of core-shell Si-mesoporous TiO2 composite nanospheres with enhanced lithium-storage properties.

Core-shell structured Si-mesoporous TiO2 (Si@mTiO2) composite nanospheres are designed and prepared via a step-by-step assembly method. Si@mTiO2 exhibit excellent lithium-storage properties when used as anode materials in lithium ion batteries. The reversible specific capacity is maintained at as high as 700 mA h g-1 with no capacity decay even after 200 cycles at 1 A g-1.

A robust indium-porphyrin framework for CO2 capture and chemical transformation.

An indium based metal-porphyrinic framework, denoted NUPF-3, was prepared based on a new amido-decorated porphyrin ligand. NUPF-3 possesses a rarely seen 4-fold interpenetrated pts framework with segmented pores and dense metalloporphyrin central sites. The structure can retain its crystallinity in commonly used solvents, as well as acidic/alkaline solutions with pH ranging from 1 to 12 for 48 h, exhibiting high chemical stability. Meanwhile, thermal analysis reveals that NUPF-3 possesses relatively high thermal stability. Owing to the presence of amido groups, structural interpenetration and a charged framework, NUPF-3 exhibits relatively high CO2 uptake. Moreover, NUPF-3 could be used as a good heterogeneous catalyst for cycloaddition of CO2 and epoxides, under relatively mild conditions, with good recyclability.

A series of robust metal-porphyrinic frameworks based on rare earth clusters and their application in N-H carbene insertion.

We herein report a series of microporous metal-porphyrinic frameworks (MPFs), denoted as NUPF-2M, based on rare earth (RE) clusters. NUPF-2M represent the first examples of RE cluster-based MPFs, possessing a rarely seen shp-a topology and exhibiting high thermal and thermal stabilities. After a post-metallization process with FeCl3, NUPF-2M is catalytically active as an efficient heterogeneous catalyst for intermolecular N-H carbene insertion.

A Stable Extra-Large-Pore Zeolite with Intersecting 14- and 10-Membered-Ring Channels.

The development of inorganic frameworks with extra-large pores (larger than 12-membered rings) has attracted considerable attention because of their potential applications in catalysis, the separation of large molecules, and so forth. We herein report the synthesis of the new extra-large-pore zeolite NUD-2 by using the supramolecular self-assembly of simple aromatic organic cations as structure-directing agents (SDAs). NUD-2 is a high-silicon-content germanosilicate with interconnecting 14×10-membered-ring channels. The SDAs in NUD-2 can be removed by calcination in air at 550 °C to yield permanent pores with a BET surface area of 500 m(2) g(-1) . Both germanium and organic cations in NUD-2 can also be removed by treatment with acid at lower temperature, thus not only affording recycling of germanium and SDAs, but also providing a highly stable siliceous zeolite. In addition, aluminum ions can be incorporated into the framework of NUD-2. The NUD-2 structure is yet another extra-large-pore zeolite synthesized by using the supramolecular self-assembling templating approach, thus demonstrating that this approach is a general and applicable strategy for synthesis of new large- and extra-large-pore zeolites.

Tuning the properties of the metal-organic framework UiO-67-bpy via post-synthetic N-quaternization of pyridine sites.

A new UiO-67-type zirconium metal organic framework (MOF) material UiO-67-bpy-Me (bpy = 2,2-bipyridine-4,4'-dicarboxylic acid, Me = methyl) was prepared by N-quaternization of the pyridine sites in UiO-67-bpy. After N-quaternization, the pristine neutral framework turned cationic while its high thermal and chemical stabilities were primarily preserved. Fast and enhanced anionic dye adsorption was observed in UiO-67-bpy-Me. In addition, despite the decrease in surface area and pore volume, UiO-67-bpy-Me exhibited an evident increase in CO2 uptake compared to UiO-67-bpy. The enhancement was ascribed to the strong interactions between CO2 and the N-quaternized framework. More importantly, as the N-quaternization has changed the electronic structure of the organic linker. UiO-67-bpy-Me showed optical absorption up to ca. 800 nm with a large red shift of 450 nm compared to the pristine UiO-67-bpy (ca. 350 nm). The extended optical absorption may lead to more efficiency in light utilization. A proof-of-concept demonstration showed that UiO-67-bpy-Me could more efficiently catalyze methyl-orange degradation under UV-Vis light irradiation than the pristine UiO-67-bpy. These findings demonstrate that N-quaternization could serve as a facile post-synthetic modification method to tune the chemical/physical properties of free pyridyl-containing MOFs.

Highly Stable Mesoporous Zirconium Porphyrinic Frameworks with Distinct Flexibility.

The construction of highly stable metal-porphyrinic frameworks (MPFs) is appealing as these materials offer great opportunities for applications in artificial light-harvesting systems, gas storage, heterogeneous catalysis, etc. Herein, we report the synthesis of a novel mesoporous metal-porphyrinic framework (denoted as NUPF-1) and its catalytic properties. NUPF-1 is constructed from a new porphyrin linker and a Zr6 O8 structural building unit, possessing an unprecedented doubly interpenetrating scu net. The structure exhibits not only remarkable chemical and thermal stabilities, but also a distinct structural flexibility, which is seldom seen in metal-organic framework (MOF) materials. By the merit of high chemical stability, NUPF-1 could be easily post-metallized with [Ru3 (CO)12 ], and the resulting {NUPF-1-RuCO} is catalytically active as a heterogeneous catalyst for intermolecular C(sp(3) )-H amination. Excellent yields and good recyclability for amination of small substrates with various organic azides have been achieved.

Two-dimensional ultra-thin SiO(x) (0 < x < 2) nanosheets with long-term cycling stability as lithium ion battery anodes.

Ultra-thin SiO(x) (0 < x < 2) nanosheets were obtained via a convenient solvothermal route from a Zintl compound CaSi2. After carbon coating, the SiOx@C nanosheet anodes exhibit high capacity, good rate and superior cycling performance for high-capacity lithium ion battery applications. The specific capacity can be maintained as high as 760 mA h g(-1) with almost no capacity decay after 400 cycles at a current density of 0.5 A g(-1).

Hollow-structured Si/SiC@C nanospheres as highly active catalysts for cycloaddition of epoxides with CO2 under mild conditions.

Hollow-structured Si/SiC@C nanospheres were prepared through a magnesiothermic reduction of resin-coated SiO2 spheres. These nanostructured materials with high surface area not only show high adsorption capacities of industrial dyes from wastewater, but also exhibit excellent catalytic activities for chemical fixation of CO2 under mild, solvent-free conditions.

Preparation of uniform Si nanoparticles for high-performance Li-ion battery anodes.

Nanostructured silicon has attracted a great deal of attention as an excellent anode material for Li ion batteries (LIBs). However, the use of Si nanomaterials in LIBs is severely hindered by their preparative methods owing to the high cost, low yield, and harsh synthetic conditions. Herein, we report a new method for the synthesis of uniform Si nanocrystals based on the magnesiothermic reduction of natural attapulgite clay. The obtained Si nanocrystals with a uniform size of ca. 10 nm are coated with polypyrrole (denoted ppy@Si) and show excellent electrochemical performance as anode materials for LIBs. After charging-discharging for 200 cycles at a current density of 0.6 A g(-1), the specific capacity value of the ppy@Si anode is ∼954 mA h g(-1). Because of the abundance of attapulgite, the obtained silicon nanoparticles can be exploited as a practical anode material for high-performance Li-ion batteries.

An extra-large-pore zeolite with intersecting 18-, 12-, and 10-membered ring channels.

Zeolites with extra-large pores have attracted great attention because of their important applications such as in hydrocracking, catalysis, and separation of large molecules. Despite much progress has been made during the past decades, the synthesis of these materials remains a big challenge. A new extra-large-pore zeolite NUD-1 (Nanjing University Du's group zeolite no. 1) is synthesized by using an approach based on supramolecular self-assemblies of small aromatic organic cations as structure-directing agents. NUD-1 possesses interconnecting 18-, 12-, and 10-membered ring channels, built from the same building units as those of ITQ-33 and ITQ-44. There coexist single 3-membered ring, double-3-membered ring and double-4-membered ring secondary building units in NUD-1, which have not been seen in any other zeolites.

Facile preparation of silicon hollow spheres and their use in electrochemical capacitive energy storage.

Nanostructured silicon hollow spheres with a thin shell have been synthesized by magnesium reduction of silica spheres, which possess a high BET surface area and are electrochemically active in capacitive energy storage with a maximum specific capacitance of 193 F g(-1) in the neutral Na(2)SO(4) aqueous solution.

Porous coordination polymers of transition metal sulfides with PtS topology built on a semirigid tetrahedral linker.

Four novel porous metal sulfide coordination polymers, [M(tpom)S(x)(SH)(y)] x z(H(2)O) (metal-sulfide frameworks, denoted MSF-n, n = 1, Cd; 2, Mn; 3, Fe; 4, Co; x = 0, y = 2 for 1, 2, and 4 and x = 0.54, y = 1.46 for 3), were solvothermally prepared by using a quadridentate linker, tetrakis(4-pyridyloxymethylene)methane (tpom), in the presence of organic sulfur compound under an acidic conditions. MSF-n (n = 1-4) is isostructural and built upon the tetrahedral tpom linker and square planar MS(x)(SH)(y) unit, which form a binodal 4,4-connected porous framework with a 2-fold interpenetrated 4(2)8(4)-pts net. With rectangular pore channels of about 5 x 6 A(2) (interatomic distances between the nearest protruding H atoms across) running along both the crystallographic a and b directions, MSF-n possesses permanent porosity with a BET surface area of 575, 622, 617, and 767 m(2)/g for MSF-1, -2, -3, and -4, respectively, as estimated from N(2) adsorption measurements. MSF-n (n = 1-4) has hydrogen storage capacities of 1.03, 1.37, 1.29, and 1.58 wt % at 77 K and 1 atm, respectively, each corresponding to 2.0 H(2) molecules per unit cell. In addition, MSF-n (n = 1-4) can adsorb 24.1, 25.0, 21.6, and 24.1 wt % of carbon dioxide and 6.0, 6.1, 5.6, and 6.4 wt % of methane, respectively, at room temperature and 20 atm.

Two unprecedented NLO-active coordination polymers constructed by a semi-rigid tetrahedral linker.

The assemblies of tetrahedral linker tetrakis[4-(carboxyphenyl)oxamethyl]methane acid (H(4)L) with ZnCl(2) and CdBr(2) yield two noncentrosymmetric, NLO-active coordination polymers [Zn(4)(L(2))(H(2)O)(3)(DMA)].2H(2)O (1) and [Cd(2)L(DMA)(2)(H(2)O)(2)] (2), respectively. 1 has an unprecedented 2-fold interpenetrating sxa topology with ferroelectric properties, while 2 has a 7-fold interpenetrating dia network.

Synthesis of an open-framework copper-germanium phosphate [Cu(H2O)2(OH)]2Ge(PO4)2.

A novel open-framework material [Cu(H(2)O)(2)(OH)](2)Ge(PO(4))(2), which was synthesized by a hydrothermal method, is built of GeO(6), CuO(6) octahedra and PO(4) tetrahedra, and possesses a network of interconnecting six- and eight-membered ring channels.