Boron Hydrogen Compounds: Hydrogen Storage and Battery Applications

About 25 years ago, Bogdanovic and Schwickardi (B. Bogdanovic, M. Schwickardi: J. Alloys Compd. 1–9, 253 (1997) discovered the catalyzed release of hydrogen from NaAlH₄. This discovery stimulated a vast research effort on light hydrides as hydrogen storage materials, in particular boron hydrogen compounds. Mg(BH₄)₂, with a hydrogen content of 14.9 wt %, has been extensively studied, and recent results shed new light on intermediate species formed during dehydrogenation. The chemistry of B₃H₈⁻, which is an important intermediate between BH₄⁻ and B₁₂H₁₂²⁻, is presented in detail. The discovery of high ionic conductivity in the high-temperature phases of LiBH₄ and Na₂B₁₂H₁₂ opened a new research direction. The high chemical and electrochemical stability of closo-hydroborates has stimulated new research for their applications in batteries. Very recently, an all-solid-state 4 V Na battery prototype using a Na₄(CB₁₁H₁₂)₂(B₁₂H₁₂) solid electrolyte has been demonstrated. In this review, we present the current knowledge of possible reaction pathways involved in the successive hydrogen release reactions from BH₄⁻ to B₁₂H₁₂²⁻, and a discussion of relevant necessary properties for high-ionic-conduction materials.     

Improved anti-inflammatory and anticancer properties of celecoxib loaded zinc oxide and magnesium oxide nanoclusters: A molecular docking and density functional theory simulation

Present study offers great prospects for the adsorption of anti-inflammatory celecoxib molecule (CXB) over the surface of zinc oxide (Zn₁₂O₁₂) and magnesium oxide (Mg₁₂O₁₂) nanoclusters in several environments by performing robust theoretical calculations. Density functional theory (DFT), time-dependent density functional theory (TDDFT) and molecular docking calculations have been extensively carried out to predict the foremost optimum site of CXB adsorption. It has been observed that the CXB molecule prefers to be adsorbed by its SO₂ site on the Zn-O and Mg-O bonds of the Zn₁₂O₁₂ and Mg₁₂O₁₂ nanoclusters instead of NH₂ and NH sites, where electrostatic interactions dominate over the bonding characteristics of the conjugate complexes. Furthermore, the presence of interactions between the CXB molecule and nanoclusters has also been evidenced by the UV–Vis absorption spectra and IR spectra. Molecular docking analysis has revealed that both adsorption states including CXB/Zn₁₂O₁₂ and CXB/Mg₁₂O₁₂ have good inhibitory potential against protein tumor necrosis factor alpha (TNF-α) and Interleukin-1 (IL-1), and human epidermal growth factor receptor 2 (HER2). Hence they might be explored as efficient TNF-α, IL-1, and HER2 inhibitors. Hence from the study, it can be anticipated that these nanoclusters can behave as an appropriate biomedical carrier for the CXB drug delivery.     

Formation and Structure of an Anionic Ruthenaborane Compound:[Et4N][(PPh3)2ClRuB12H12]

在研究RuCl2(PPh3)3 和 closo-B10H102- 在乙醇中的反应时,意外分离得到一个阴离子型的钌硼烷化合物[Et4N][(PPh3)2ClRuB12H12], 并且经过红外光谱和单晶X射线衍射分析确证. 在其结构中,闭式B12H122-配体与Ru(II)中心通过三个B-H-Ru三中心-二电子键结合. 分析原因应是在通过文献方法制备闭式B10H102-时的少量副产物闭式B12H122-在反应体系中与RuCl2(PPh3)3反应而生成了标题化合物. 根据硼烷簇合物的电子计数规则, 标题化合物也可以看成是含有2n (n为簇顶点数)个骨架电子的pileo型簇合物, 具有加帽(capped)的闭式多面体骨架构型. 这是第一个阴离子型的含有闭式B12H122- 的钌化合物.     

Borane Derivatives: A New Class of Super‐ and Hyperhalogens

Super‐ and hyperhalogens are a class of highly electronegative species whose electron affinities far exceed those of halogen atoms and are important to the chemical industry as oxidizing agents, biocatalysts, and building blocks of salts. Using the well‐known Wade–Mingos rule for describing the stability of closo‐boranes B_nH_n^2? and state‐of‐the‐art theoretical methods, we show that a new class of super‐ and hyperhalogens, guided by this rule, can be formed by tailoring the size and composition of borane derivatives. Unlike conventional superhalogens, in which a central metal atom is surrounded by halogen atoms, the superhalogens formed according to the Wade–Mingos rule do not have to have either halogen or metal atoms. We demonstrate this by using B₁₂H₁₃ and its isoelectronic cluster CB₁₁H₁₂ as examples. We also show that while conventional superhalogens containing alkali atoms require at least two halogen atoms, a single borane‐like moiety is sufficient to give M(B₁₂H₁₂) clusters (M=Li, Na, K, Rb, Cs) superhalogen properties. In addition, hyperhalogens can be formed by using the above superhalogens as building blocks. Examples include M(B₁₂H₁₃)₂ and M(CB₁₁H₁₂)₂ (M=Li–Cs). This finding opens the door to an untapped source of superhalogens and weakly coordinating anions with potential applications.     

[(CH3)Al(CH2)]12: Methylaluminomethylene (MAM-12)

The molecular structure of enigmatic “poly(aluminium-methyl-methylene)” (first reported in 1968) has been unraveled in a transmetalation reaction with gallium methylene [Ga₈(CH₂)₁₂] and AlMe₃. The existence of cage-like methylaluminomethylene moieties was initially suggested by the reaction of rare-earth-metallocene complex [Cp*₂Lu{(μ-Me)₂AlMe₂}] with excess AlMe₃ affording the deca-aluminium cluster [Cp*₄Lu₂(μ₃-CH₂)₁₂Al₁₀(CH₃)₈] in low yield (Cp*=C₅Me₅). Treatment of [Ga₈(CH₂)₁₂] with excess AlMe₃ reproducibly gave the crystalline dodeca-aluminium complex [(CH₃)₁₂Al₁₂(μ₃-CH₂)₁₂] (MAM-12). Revisiting a previous approach to “poly(aluminium-methyl-methylene” by using a (C₅H₅)₂TiCl₂/AlMe₃ (1 : 100) mixture led to amorphous solids displaying solubility behavior and spectroscopic features similar to those of crystalline MAM-12. The gallium methylene-derived MAM-12 was used as an efficient methylene transfer reagent for ketones.     

Study on the surface interaction of Furan with X12Y12 (X = B,Al, and Y = N,P) semiconductors: DFT calculations

Chemisorption of Furan on the surfaces of four different semiconductors (Al₁₂N₁₂, Al₁₂P₁₂, B₁₂N₁₂, and B₁₂P₁₂) has been investigated, and the results have been compared using density functional theory in terms of energetic, geometric, and electronic property. Two functionals, dispersion corrected (wB97XD) and non‐corrected (B3LYP), have been used for calculation of binding energy. The results show that chemisorption of Furan on these semiconductors is in the order of Al₁₂N₁₂ (−98.4 kJ mol⁻¹) > Al₁₂P₁₂ (−77.5 kJ mol⁻¹) > B₁₂N₁₂ (−46.6 kJ mol⁻¹) > B₁₂P₁₂ (−18.3 kJ mol⁻¹), while the order of change in the HOMO–LUMO gap of semiconductors upon adsorption of Furan is found as B₁₂N₁₂ > B₁₂P₁₂ > Al₁₂P₁₂ > Al₁₂N₁₂, which implies to the higher changes in the electronic structure of B‐containing clusters (B₁₂N₁₂ and B₁₂P₁₂) compared to Al‐containing clusters (Al₁₂N₁₂ and Al₁₂P₁₂). The NBO charge analyses reveal maximum and minimum charge transfer upon adsorption of Furan on B₁₂N₁₂ and B₁₂P₁₂, respectively. Based on the results, it was found that Al₁₂N₁₂ and B₁₂N₁₂ as the most appropriate adsorbent and the most sensitive sensor for Furan, respectively.     

Novel silicon nanorings: Persilacyclacenes at DFT

Structures, energies, and aromatic characters are compared and contrasted for a series of [n]persilacyclacenes with n = 6–12: Si₂₄H₁₂, Si₂₈H₁₄, Si₃₂H₁₆, Si₃₆H₁₈, Si₄₀H₂₀, Si₄₄H₂₂, and Si₄₈H₂₄, respectively, at B3LYP levels (n, number of fused benzenoid rings). These are a brand of silicon nanorings that bear a resemblance to the shortest zig‐zag silicon nanotubes (SiNTs), henceforth referred to as SiNRs. The NBO results show nearly sp²‐hybridization for virtually all Si atoms of our SiNRs. This is in contrast to most reports where sp³‐hybridization is proposed for typical SiNTs. Comparison between the optimized SiNRs and their corresponding planar (polyacenic) forms shows longer bond lengths for the former, due to their curvatures. Except for sterically hindered Si₂₄H₁₂ (n = 6), all even SiNRs (n = 8, 10, and 12), are more aromatic than the odd ones (n = 7, 9, and 11). Such a higher aromaticity is witnessed inside, outside, and on the surface of the scrutinized SiNRs. Also, except for Si₄₄H₂₂ (n = 11), the energy gaps (ΔE_HOMO?LUMO) for the odd set of SiNRs, as well as the even set, appear inversely proportional to their corresponding diameters, per se. Except for the sterically hindered SiNRs with n = 6 or 7, all the even SiNRs enjoy a higher stability (aromaticity) and conductivity for showing lower ΔE_HOMO?LUMO than the odd ones. Evidently, the ideal diameter for persilacyclacenes (SiNRs) studied is from 0.92 to 1.42 nm, corresponding to n = 8–12, respectively. Higher than 1.42 nm causes structural disorders while lower than 0.92 brings about bond localization due to the high‐steric effects. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Theoretical investigation on icosahedral C60(FeCp)12: A hybrid of C60 and ferrocene

A perfect hybrid complex C₆₀(FeCp)₁₂ is predicted using density functional theory method_. This fullerene derivative could be view as a C₆₀ cage of which each C₅ ring coordinates a (FeCp) ligand. Theoretical calculation reveals that it has a large lowest unoccupied molecular orbital–highest unoccupied molecular orbital gap (2.53 eV) and keeps the I_h symmetry of C₆₀. But the C? C bond length of its inner C₆₀ cage trends to be uniform, which is quite different from the bonding character of C₆₀ fullerene. Further investigation reveals that the chemical bonding, TDOS and the aromaticity of the (C₅FeCp) unit in C₆₀(FeCp)₁₂ are similar as those of ferrocene molecule, which indicates the similarity of their electronic properties. So, this compound could be viewed as the combination of ferrocene molecules. Thus, its unconventional formation process from 12 Fe(Cp)₂ is proposed and the reaction energy is calculated. As the C₆₀(FeCp)₁₂ compound has the geometry framework as C₆₀ and the electronic characters as ferrocene, it would inherit the outstanding properties from both two molecules and have wild potential applications in nanochemistry. We hope our study could give some references for the further investigation and experimental synthesis research of the C₆₀(FeCp)₁₂ compound. © 2015 Wiley Periodicals, Inc.     

“Sponge Crystal”: a novel class of microporous single crystals formed by self-assembly of polyoxometalate (NH4)3PW12O40 nanocrystallites

In this account, a new concept of “sponge crystals” is presented on the basis of new interpretation of our previous results of porous heteropolyacids, that is, porous aggregates of self-assembled (NH₄)₃PW₁₂O₄₀ nanocrystallites (Ito, Inumaru, and Misono, J. Phys. Chem. B 101 (1997) 9958; Chem. Mater. 13 (2001) 824) “Sponge crystals” are defined as single crystals having continuous voids within them, but unlike zeolites, no intrinsic structural pores. This new category includes molecular single crystals having continuous voids originating from series of neighboring vacancies (≥1 nm) of the constituent large molecules, affording nanospaces in the crystals. A typical example of “sponge crystals” is (NH₄)₃PW₁₂O₄₀, which is formed via the dropwise addition of ammonium hydrogen carbonate into an H₃PW₁₂O₄₀ aqueous solution (titration method) at 368 K. The resulting (NH₄)₃PW₁₂O₄₀ nanocrystallites (ca. 6–8 nm) then self-assemble with the same crystal orientation to form porous dodecahedral aggregates in the solution. During the formation process, necks grow epitaxially between the surfaces of the nanocrystallites (“Epitaxial Self-Assembly”) to form aggregates of which each aggregate has an ordered structure as a whole single crystal. Although the crystal structure of (NH₄)₃PW₁₂O₄₀ has no intrinsic structural(“built-in”) pores, X-ray diffraction, electron diffraction and gas adsorption experiments all reveal that each (NH₄)₃PW₁₂O₄₀ aggregate is comprised of a single crystal bearing many micropores. These pores are considered to be continuous spaces as neighboring vacancies of the molecules (anions and cations) originating from the residual spaces between the self-assembled nanocrystallites. The porous (NH₄)₃PW₁₂O₄₀ single crystals are considered a special case of “mesocrystals,” as was recently discussed by Cölfen and Antonietti (Angew. Chem. Int. Ed. 44 (2005) 5576). In contrast to most “mesocrystals,” which are generally polycrystalline in nature, each aggregate of (NH₄)₃PW₁₂O₄₀ is a characteristic porous single crystal. Furthermore, the micropores of (NH₄)₃PW₁₂O₄₀ are totally different from those found in other microporous crystals: zeolites have “built-in” pores defined by their crystal structure, while the (NH₄)₃PW₁₂O₄₀ nanocrystallites have none. Since (NH₄)₃PW₁₂O₄₀ micropores are continuous spaces as neighboring vacancies of the molecules, the shapes of the (NH₄)₃PW₁₂O₄₀ pores can in principle, assume various connectivities or networks within the crystal, and as such, are subsequently termed: “sponge crystals.”     

Penicillamine functionalized B12N12 and B12CaN12 nanocages act as potential inhibitors of proinflammatory cytokines: A combined DFT analysis,ADMET and molecular docking study

The adsorption of penicillamine (PCA) on pure B₁₂N₁₂ and B₁₂CaN₁₂ nanocages in aqueous and chloroform solvents has been evaluated using density functional theory (DFT) calculations. The interaction of PCA on B₁₂N₁₂ nanocages is chemisorption through its four nucleophilic sites: amine, carbonyl, hydroxyl and thiol. The most stable adsorption configuration was achieved when zwitterionic PCA adsorbs via its carbonyl group in water with value of ?1.723 eV, in contrast, when neutral PCA adsorbs via its amine group in chloroform with value of ?1.68 eV. Intercalated calcium ion within B₁₂N₁₂ nanocage (B₁₂CaN₁₂) was shown to attract PCA onto nanocage surface, resulting in higher solubility and adsorption energy after their complexation in water and chloroform. The adsorption of multiple PCA molecules from their amine and carbonyl groups on pure and B₁₂CaN₁₂ nanocages were also evaluated where two and three molecules can be chemisorbed on boron atoms of the nanocage surfaces with the adsorption energy per PCA reduces slightly with the increasing the amount of drugs due to the curvature effects. Molecular docking study indicates that PCA from its NH₂ group on B₁₂CaN₁₂ nanocage has the best binding affinity and inhibition potential of tumor necrosis factor-alpha (TNF-α) and Interleukin-1 (IL-1) receptors as compared with the other adsorption systems. Molecular docking and ADMET analysis displayed that the chosen compounds pass Lipinski Rule and have appropriate pharmacokinetic features suitable as models for developing anti-inflammatory agents.     

Giant Hollow Heterometallic Polyoxoniobates with Sodalite‐Type Lanthanide–Tungsten–Oxide Cages: Discrete Nanoclusters and Extended Frameworks

The first series of niobium–tungsten–lanthanide (Nb‐W‐Ln) heterometallic polyoxometalates {Ln₁₂W₁₂O₃₆(H₂O)₂₄(Nb₆O₁₉)₁₂} (Ln=Y, La, Sm, Eu, Yb) have been obtained, which are comprised of giant cluster‐in‐cluster‐like ({Ln₁₂W₁₂}‐in‐{Nb₇₂}) structures built from 12 hexaniobate {Nb₆O₁₉} clusters gathered together by a rare 24‐nuclearity sodalite‐type heterometal–oxide cage {Ln₁₂W₁₂O₃₆(H₂O)₂₄}. The Nb‐W‐Ln clusters present the largest multi‐metal polyoxoniobates and a series of rare high‐nuclearity 4d‐5d‐4f multicomponent clusters. Furthermore, the giant Nb‐W‐Ln clusters may be isolated as discrete inorganic alkali salts and can be used as building blocks to form high‐dimensional inorganic–organic hybrid frameworks.     

New coordination polymers of silver(I) based on dodecahydro-<Emphasis Type="Italic">closo</Emphasis>-dodecaborate anion: Synthesis and structure

It has been demonstrated that the reaction of Cat[Ag[B₁₂H₁₂]] or [Ag₂[B₁₂H₁₂]] with chelating ligands L (L = bipy, phen) leads to the selective formation of stable [(Ag₂(L)₂[B₁₂H₁₂]] _n 1D polymers irrespective of the nature of cation (Cat) in the starting reagent, the ratio of the reaction components, and the solvent used. The structures of [Ag₂(bipy)₂[B₁₂H₁₂]] _n · 2CH₃CN and [Ag₂(phen)₂[B₁₂H₁₂]] _n · DMF have been determined by X-ray crystallography. It has been demonstrated that the [B₁₂H₁₂]^2? anion in polymer chains acts as a bridging ligand coordinated to silver atoms through edges or through an edge and a vertex of the icosahedron. The Ag–B(H) and Ag–H(B) distances are within 2.638(3)–3.074(3) and 1.90–2.80 Å, respectively. These complexes are the first examples of 1D coordination polymers based on the [B₁₂H₁₂]^2? anion and azaheterocyclic ligands L.     

四种Keggin型多酸纳米材料的制备及其吸附有机染料的性能

以4种Keggin型多酸作为原料(分别为H₃PW₁₂O₄₀·36H₂O(简写为PW₁₂^a)、H₃PMo₁₂O₄₀·34H₂O(简写为PMo₁₂^a)、H₄SiW₁₂O₄₀·35H₂O(简写为SiW₁₂^a)和H₄GeW₁₂O₄₀·40H₂O(简写为GeW₁₂^a)),采用表面活性剂智能化控制的软化学法制备了相应的4种Keggin型多酸纳米材料,分别为Ag₃PW₁₂O₄₀·36H₂O(简写为PW₁₂^b)、Ag₃PMo₁₂O₄₀·34H₂O(简写为PMo₁₂^b)、Ag₄SiW₁₂O₄₀·35H₂O(简写为SiW₁₂^b)和Ag₄GeW₁₂O₄₀·40H₂O(简写为GeW₁₂^b)。采用IR、UV-Vis、XRD和SEM表征多酸的结构和纳米粒子的形貌。在室内黑暗条件下,100mg样品可在5min内把20mg·L^-1的100mL亚甲基蓝(MB)染料溶液脱色,使其变为接近无色,吸附效率最高可达96.3%,吸附效率大小为PMo₁₂^b >PW₁₂^b >GeW₁₂^b >SiW₁₂^b。相同条件下,100mg样品使20mg·L^-1的100mL罗丹明B(RhB)染料溶液30min内脱色完全,脱色效率最高可达96.1%,吸附效率大小为PW₁₂^b >PMo₁₂^b >SiW₁₂^b >GeW₁₂^b。说明该4种多酸纳米材料具有较高的吸附有机染料性能。     

P/O ligand systems: Synthesis and reactivity of primary and secondary o-phosphinophenols

Several organometallic reagents such as lithium 2-lithio 4-methylphenolate 1 intermediates formed by orthometallation of o-bromoaryloxy-phosphorus(V)- 2 or -phosphorus(III)-derivatives 3 with magnesium and sodium, respectively, as well as O-methoxymethyl-protected o-lithio-4-methylphenol 4 were used to synthesize suitable precursors 5,6,9,10 of primary and secondary o-phosphinophenols. The P–C bond formation involved coupling with ClPR(NMe₂), CIPR(O)(OEt) or an intramolecular carbanionic O → C shift of the P-substituent. Reduction with LiAlH₄, in the cases of phosphonous or phosphinous acid amides after alcoholysis (to 7,8,11 ), produced primary and secondary o-phosphinophenols 12 , respectively, or O-protected derivatives 13 . o-Phosphinophenols 12 are easily protonated at the phosphorus atom, supported by a P⁺-H … O hydrogen bridge. Metallation ( 14 ), acylation, and silylation ( 16,17 ) take place preferably at the hyxdroxy group and alkylation at the phosphorus atom. Alkylation of 12 and 14 was found to be slow, but C,O-dilithiated species 15 react to give P-secondary ( 12b,d,e, ) or P-tertiary products ( 20,21 ). Cyclization of 15a with Me₂SiCl₂ affords the 2,3-dihydro-1,3,2-benzoxaphosphasilol 22 , cyclocondensation of 12c with RP(NMe₂)₂ or ClP(NMe₂)₂ furnishes 2,3-dihydro-1,2,3- benzodiphospholes 23 and 24 . A phosphiniden-phosphoran 25 is detected in the reaction between 12a and P(NMe₂)₃. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 383–396, 1997     

Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions

The family of polyoxometalate (POM) intercalated layered double hydroxide (LDH) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW₁₂O₄₀]^3? (PW₁₂) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such an intercalated compound of Mg_0.73Al_0.22(OH)₂ [PW₁₂O₄₀]_0.04?0.98 H₂O (Mg₃Al‐PW₁₂) has been successfully obtained by applying a spontaneous flocculation method. The Mg₃Al‐PW₁₂ has been fully characterized by using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT‐IR, NMR, BET). XRD patterns of Mg₃Al‐PW₁₂ exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg₃Al‐PW₁₂ as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z‐CH₂‐Z′ type substrates (ethyl cyanoacetate and malononitrile) at 60 °C in mixed solvents (V_2‐propanol:V_water=2:1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg₃Al‐PW₁₂ composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg₃Al‐PW₁₂‐catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47 980 reported so far for this reaction.     

ABC triblock polymethacrylates: Group transfer polymerization synthesis of the ABC,ACB, and BAC topological isomers and solution characterization

ABC triblock copolymers of methyl methacrylate (MMA), (dimethylamino)-ethyl methacrylate (DMAEMA), and tetrahydropyranyl methacrylate (THPMA) consisting of 12 units of each type of monomer were synthesized by group transfer polymerization (GTP). These were the three topological isomers with differentblock sequences: DMAEMA₁₂-THPMA₁₂-MMA₁₂, DMAEMA₁₂-MMA₁₂-THPMA₁₂, and THPMA₁₂-DMAEMA₁₂-MMA₁₂. The molecular weights and molecular weight distributions of the copolymers were determined by gel permeation chromatography (GPC) in tetrahydrofuran, and their number-average degrees of polymerization and copolymer compositions were calculated by proton nuclear magnetic resonance spectroscopy (¹H-NMR). These molecular weights and degrees of polymerization corresponded closely to the values expected from the monomer/initiator ratios. The polydispersities were low as expected for GTP, and ranged from 1.09 to 1.25. The three triblocks were chemically modified by converting the THPMA units to methacrylic acid (MAA) units either by thermolysis or acid hydrolysis. The resulting ABC triblock poly-ampholytes were characterized by ¹H-NMR spectroscopy and hydrogen ion titration. Aqueous GPC studies in 1.0M NaCl at pH 8.5 showed that the triblock copolymers form micelles whose size depends on their block sequence. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 617–631, 1998     

Carbon-doped boron-nitride fullerenes as efficient metal-free catalysts for oxidation of SO2: a DFT study

The aim of this study is to explore the potential of utilizing carbon-doped fullerene-like boron-nitride nanocages (B₁₁N₁₂C and B₁₂N₁₁C) as an efficient metal-free catalyst for the oxidation of SO₂ to SO₃ molecule in the presence of N₂O. The oxidation of SO₂ over B₁₁N₁₂C includes two steps. First, the N₂O molecule is decomposed into an activated oxygen atom (O*) and N₂ molecule, and then the SO₂ molecule is oxidized by the O* species. In the case of B₁₂N₁₁C and B₁₂N₁₂, however, the reaction starts with the coadsorption of SO₂ and N₂O molecules, followed by the decomposition of N₂O and the formation of SO₃ and N₂ species. According to our results, B₁₁N₁₂C exhibits larger catalytic activity for the SO₂ oxidation compared with B₁₂N₁₁C and B₁₂N₁₂ clusters. The estimated activation energy for the SO₂ + O* → SO₃ reaction catalyzed over the B₁₁N₁₂C surface is 5.8 kcal/mol, which is comparable with those reported about noble-metal catalysts. The results of this study can be useful for developing metal-free catalysts based on C-doped BN nanostructures.

     

四种Keggin型多酸纳米材料的制备及其吸附有机染料的性能

以4种Keggin型多酸作为原料(分别为H₃PW₁₂O₄₀·36H₂O(简写为PW₁₂^a)、H₃PMo₁₂O₄₀·34H₂O(简写为PMo₁₂^a)、H₄SiW₁₂O₄₀·35H₂O(简写为SiW₁₂^a)和H₄GeW₁₂O₄₀·40H₂O(简写为GeW₁₂^a)),采用表面活性剂智能化控制的软化学法制备了相应的4种Keggin型多酸纳米材料,分别为Ag₃PW₁₂O₄₀·36H₂O(简写为PW₁₂^b)、Ag₃PMo₁₂O₄₀·34H₂O(简写为PMo₁₂^b)、Ag₄SiW₁₂O₄₀·35H₂O(简写为SiW₁₂^b)和Ag₄GeW₁₂O₄₀·40H₂O(简写为GeW₁₂^b)。采用IR、UV-Vis、XRD和SEM表征多酸的结构和纳米粒子的形貌。在室内黑暗条件下,100 mg样品可在5 min内把20 mg·L^-1的100 mL亚甲基蓝(MB)染料溶液脱色,使其变为接近无色,吸附效率最高可达96.3%,吸附效率大小为PMo₁₂^b > PW₁₂^b > GeW₁₂^b > SiW₁₂^b。相同条件下,100 mg样品使20 mg·L^-1的100 mL罗丹明B(RhB)染料溶液30 min内脱色完全,脱色效率最高可达96.1%,吸附效率大小为PW₁₂^b > PMo₁₂^b > SiW₁₂^b > GeW₁₂^b。说明该4种多酸纳米材料具有较高的吸附有机染料性能。     

Ln12‐Containing 60‐Tungstogermanates: Synthesis,Structure, Luminescence,and Magnetic Studies

A new class of hexameric Ln₁₂‐containing 60‐tungstogermanates, [Na(H₂O)₆?Eu₁₂(OH)₁₂(H₂O)₁₈Ge₂(GeW₁₀O₃₈)₆]^39? ( Eu₁₂ ), [Na(H₂O)₆?Gd₁₂(OH)₆(H₂O)₂₄Ge(GeW₁₀O₃₈)₆]^37? ( Gd₁₂ ), and [(H₂O)₆?Dy₁₂(H₂O)₂₄(GeW₁₀O₃₈)₆]^36? ( Dy₁₂ ), comprising six di‐Ln‐embedded {β(4,11)‐GeW₁₀} subunits was prepared by reaction of [α‐GeW₉O₃₄]^10? with Ln^III ions in weakly acidic (pH 5) aqueous medium. Depending on the size of the Ln^III ion, the assemblies feature selective capture of two (for Eu₁₂ ), one (for Gd₁₂ ), or zero (for Dy₁₂ ) extra Ge^IV ions. The selective encapsulation of a cationic sodium hexaaqua complex [Na(H₂O)₆]⁺ was observed for Eu₁₂ and Gd₁₂ , whereas Dy₁₂ incorporates a neutral, distorted‐octahedral (H₂O)₆ cluster. The three compounds were characterized by single‐crystal XRD, ESI‐MS, photoluminescence, and magnetic studies. Dy₁₂ was shown to be a single‐molecule magnet.     

Novel BC2N Nanocages: A DFT Investigation

We modeled and studied three types of novel B₁₂C₂₄N₁₂ cages. The structure of these cages was inspired by those of BC₂N nanotubes and the B₂₄N₂₄ fulborene skeleton. Density functional theory was used to investigate the various properties of the cages. All three isomers of B₁₂C₂₄N₁₂ were vibrationally stable. The highest occupied molecular orbital‐lowest unoccupied molecular orbital band gap was dependent on the BC₂N cage type. The B₁₂C₂₄N₁₂‐II cage was the most favorable nanocage and exhibited a large electric dipole moment. Natural bonding orbital (NBO) analysis confirmed the existence of lone pairs and unoccupied orbitals in the B₁₂C₂₄N₁₂ cages. New donor–acceptor interactions of natural MOs (Molecular Orbitals) were observed in BC₂N nanocages. The NBO and atomic polar tensor charges appeared to be fairly well correlated, showing that atomic charges can be obtained at a lower computational cost in this way.