Adsorption of sarin and chlorosarin onto the Al12N12 and Al12P12 nanoclusters: DFT and TDDFT calculations

This study provides details of the electronic and optical structures and binding energies of sarin (SF) and chlorosarin (SC) with Al–N and Al–P surfaces of Al₁₂N₁₂ and Al₁₂P₁₂ nanoclusters in the gas phase. The adsorption mechanism of SF and SC on these nanoclusters containing the Al³⁺ central cation was studied. Optimized geometries and thermodynamic parameters of SF and SC adsorption complexes were calculated. SF and SC are chemisorbed on these nanoclusters because of the formation of PO···Al bonds. The chemical bond is formed between an oxygen atom of SF and SC and an aluminum atom of fullerene-likes (chemisorption). However, the binding energies of the complexes with the Al₁₂N₁₂ nanocluster are larger than these values for the Al₁₂P₁₂ nanocluster. The interaction enthalpy and Gibbs free energy of all studied systems were found to be negative. We can conclude that SF and SC will be adsorbed preferably on Al₁₂N₁₂ nanocluster.     

Theoretical study of isomerism of compounds of CO and CO2 molecules with aluminum clusters Al13, Al12Ti,and Al12Ni

Structural characteristics, vibrational frequencies, and energies of isomers of compounds of CO and CO₂ molecules with the centered aluminum cluster Al₁₃ and its doped analogues Al₁₂M (M = Ti and Ni) have been calculated by the density functional theory method. For the Al₁₂MCO compounds, the most favor-able are two “fragment” isomers in which the C and O atoms are separated and built into the cluster cage, completing it to a 14-vertex polyhedron. In one of them, the C and O atoms are in the capping positions over adjacent trigonal MAl₂ faces; in the second isomer, there is the five-coordinate C* atom located in the center of a tetragonal MAl3 face and bound to the central Al atom through the long fifth bond. The “coordinated” isomers, in which the CO molecule is coordinated as a ligand to a cluster vertex, edge, or face, are unstable to removal of CO for Al₁₃CO, close in energy to the fragment isomers for Al₁₂NiCO, and considerably higher on the energy scale than the fragment isomers but remain stable to CO removal for Al₁₂TiCO. For the Al₁₂MCO₂ compounds, the most favorable is the fragment isomer in which both oxygen atoms are in the capping positions over adjacent faces and the C* atom is five-coordinate. The alternative oxo carbonyl isomer Al₁₂MO(CO) is close to the lowest-lying one in the case of M = Ni and is ～56 kcal/mol higher on the energy scale in the case of M= Ti. The less stable Al₁₂M(CO₂) isomer is the complex in which the CO₂ ligand is coordinated to an M-Al edge. According to calculations, addition of CO to Al₁₂MO and addition of CO₂ to Al₁₂M to form, respectively, Al₁₂MO(CO) and Al₁₂M(CO₂) can occur without noticeable barrier. The Al₁₂M(CO₂) and Al₁₂MO(CO) isomers are separated by a barrier, moderate for M = Ti (～16 kcal/mol) and small for M = Ni (～6 kcal/mol).     

Pb3Al2F12: Crystal structure of a cyclo-fluoroaluminate related to Ba3Al2F12

Pb₃Al₂F₁₂ is a fluorometalate obtained in single-crystal form by hydrothermal synthesis. It crystallizes in the monoclinic system, space group P 2₁/n, with a = 9.435(6) Å, b = 9.610(5) Å, c = 10.100(9) Å, β = 90.59(5)°, V = 915.7(2) ų, Z = 4. The structure was solved from single crystal using 3 044 unique reflections (MoKα, λ = 0.71073 Å), R = 0.0463, R_w = 0.0465. The structure exhibits isolated tetrameric groups of octahedra encaged in a subnetwork of independent fluoride polyhedra and is related to that of Ba₃Al₂F₁₂. A discussion about the existence and the structure of A₃M₂F₁₂ compounds is given.     

Adsorption properties of hydrazine on pristine and Si-doped Al12N12 nano-cage

The interaction of hydrazine (N₂H₄) molecule with pristine and Si-doped aluminum nitride (Al₁₂N₁₂) nano-cage was investigated using the density functional theory calculations. The adsorption energy of N₂H₄ on pristine Al₁₂N₁₂ in different configurations was about –1.67 and –1.64 eV with slight changes in its electronic structure. The results showed that the pristine nano-cage can be used as a chemical adsorbent for toxic hydrazine in nature. Compared with very low sensitivity between N₂H₄ and Al₁₂N₁₂ nano-cage, N₂H₄ molecule exhibits high sensitivity toward Si-doped Al₁₂N₁₂ nano-cage so that the energy gap of the Si-doped Al₁₂N₁₂ nano-cage is changed by about 31.86% and 37.61% for different configurations in the Si_Al model and by about 26.10% in the Si_N model after the adsorption process. On the other hand, in comparison with the Si_Al model, the adsorption energy of N₂H₄ on the Si_N model is less than that on the Si_Al model to hinder the recovery of the nano-cage. As a result, the Si_N Al₁₂N₁₁ is anticipated to be a potential novel sensor for detecting the presence of N₂H₄ molecule.     

Zur Kristallstruktur von Ba3Al2F12

Concerning the Crystal Structure of Ba₃Al₂F₁₂ Preparing BaMnAlF₇ we obtained single crystals of Ba₃Al₂F₁₂ as a by‐product (a = 1020.3(2), b = 988.5(1), c = 952.2(1) pm, space group Pnnm, Z = 4). The redetermination confirmed the structure already known, but improved the results (R₁′ = 0.028 and wR₂ = 0.06 for 1908 and 2717 reflections, resp.). An interpretation is given for the relation of distances within the tetrameric anion [Al₄F₂₀]^8— (average Al—F: 180, 1 pm). The construction of the cationic frame [Ba₃F₂]⁴⁺ is discussed.     

Molecular modeling investigation of adsorption of Zolinza drug on surfaces of the B12N12 and Al12N12 nanocages

Structural Chemistry - In the current work, the adsorption of Zolinza (ZOL) drug on B12N12 and Al12N12 nanocages was investigated using density functional theory (DFT) and time-dependent DFT...     

Phase transition in mayenite Ca12Al14O33

A phase transition in Ca₁₂Al₁₄O₃₃ has been discovered and investigated by thermogravimetric analysis, differential scanning calorimetry, dilatometry, and high-temperature X-ray diffraction. The phase transition occurs at 922 ± 45 K (??H = ?406 ± 13 kJ/mol, ??S = ?440 ± 14 J/(mol K)) and is presumably a first-order one. It does not change the symmetry of the cationic subsystem. The phase transition is difficult to reveal because the material changes its mass, probably by releasing water bound in several different ways.     

Modeling of Al12N12, Mg12O12, Ca12O12, and C23N nanostructured as potential anode materials for sodium-ion battery

Journal of Solid State Electrochemistry - The rising costs of lithium and other versatile metals which are of electrochemical importance have sprouted concerns in the electrochemical world. Sodium...     

[(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.     

Crystallization of ZSM-12 Zeolite with Different Si/Al Ratio

In this work the acid properties of a series of HZSM-12 zeolites with different Si/Al ratio were studied. The ZSM-12 crystals were synthesized by the hydrothermal method starting from a gel with the following molar composition: 20MTEA:10Na₂O:x Al₂O₃:100SiO₂:2000H₂O, with x = 0.50, 0.67, 1, 1.25 and 2, respectively. The gels were crystallized at 140^∘C for 6 days, then washed, dried and calcined to remove the MTEA template. The samples were ion-exchanged with an ammonium chloride solution and calcined again to obtain the zeolites in the acid form. The materials thus obtained were characterized by XRD, SEM, BET, TG and n-butylamine adsorption. The Si/Al ratio in the reaction mixture affects the amount of zeolite produced and the size of the particles. The XRD analysis indicated that the ZSM-12 zeolite crystallizes in a pure form only with Si/Al ratio above 33. The SEM analysis showed the presence of crystallites with very well defined prismatic shapes. The removal of the MTEA of the pores of the ZSM-12 by TG indicated that there are two kinds of internal sites occupied by MTEA inside the structure. The BET area of the ZSM-12 decreases proportionally with the crystallinity of materials. The desorption of n-butylamine showed that the acid site density is proportional to aluminum content, but the Si/Al ratio shows little influence on the relative strengths of these sites.     

化合物Al2Mo3-xWxO12的合成与结构

合成并表征了一系列化合物Al₂Mo_3-xW_xO₁₂ x=0,0.5,1.0,1.5和2.0的化合物是以单斜晶系Al₂(MoO₄)₃为基质的化合物和固溶体,空间群为P2₁/a;x=2.5和3.0的标题化合物是以正交晶系Al₂(WO₄)₃为基质的固溶体和化合物,空间群为Pbcn.利用粉末X射线衍射图谱全谱拟合的方法精修了x=0,0.5,1.0,1.5,2.0的标题化合物的结构,讨论其相变机理.     

Cluster-assembled materials based on M12N12 (M = Al, Ga) fullerene-like clusters

We report the results of density functional theory calculations on cluster-assembled materials based on M(12)N(12) (M = Al, Ga) fullerene-like clusters. Our results show that the M(12)N(12) fullerene-like structure with six isolated four-membered rings (4NRs) and eight six-membered rings (6NRs) has a T(h) symmetry and a large HOMO-LUMO gap, indicating that the M(12)N(12) cluster would be ideal building blocks for the synthesis of cluster-assembled materials. Via the coalescence of M(12)N(12) building blocks, we find that the M(12)N(12) clusters can bind into stable assemblies by either 6NR or 4NR face coalescence, which enables the construction of rhombohedral or cubic nanoporous framework of varying porosity. The rhombohedral-MN phase is energetically more favorable than the cubic-MN phase. The M(12)N(12) fullerene-like structures in both phases are maintained and the M-N bond lengths between M(12)N(12) monomers are slightly larger than that in isolated M(12)N(12) clusters and the bulk wurtzite phases. The band analysis of both phases reveals that they are all wide-gap semiconductors. Because of the nanoporous character of these phases, they could be used for gas storage, heterogeneous catalysis, filtration and so on.     

Cubic aluminum silicides RE8Ru12Al49Si9(Al(x)Si12-x) (RE = Pr, Sm) from liquid aluminum. Empty (Si,Al)12 cuboctahedral clusters and assignment of the Al/Si distribution with neutron diffraction.

Two new quaternary aluminum silicides, RE8Ru12Al49Si9(Al(x)Si12-x) (x approximately 4; RE = Pr, Sm), have been synthesized from Sm (or Sm2O3), Pr, Ru, and Si in molten aluminum between 800 and 1000 degrees C in sealed fused silica tubes. Both compounds form black shiny crystals that are stable in air and NaOH. The Nd analog is also stable. The compounds crystallize in a new structural type. The structure, determined by single-crystal X-ray diffraction, is cubic, space group Pm3m with Z = 1, and has lattice parameters of a = 11.510(1) A for Sm8Ru12Al49Si9(Al(x)Si12-x) and a = 11.553(2) A for Pr8Ru12Al49Si9(Al(x)Si12-x) (x approximately 4). The structure consists of octahedral units of AlSi6, at the cell center, Si2Ru4Al8 clusters, at each face center, SiAl8 cubes, at the middle of the cell edges, and unique (Al,Si)12 cuboctohedral clusters, at the cell corners. These different structural units are connected to each other either by shared atoms, Al-Al bonds, or Al-Ru bonds. The rare earth metal atoms fill the space between various structural units. The Al/Si distribution was verified by single-crystal neutron diffraction studies conducted on Pr8Ru12Al49Si9(Al(x)Si12-x). Sm8Ru12Al49Si9(Al(x)Si12-x) and Pr8Ru12Al49Si9(Al(x)Si12-x) show ferromagnetic ordering at Tc approximately 10 and approximately 20 K, respectively. A charge of 3+ can be assigned to the rare earth atoms while the Ru atoms are diamagnetic.     

DTA studies of 12CaO·7Al2O3 polymorphism

The polymorphism of 12CaO·7Al₂O₃ has been studied by means of a Setaram G-24 thermoanalyser and by X-ray diffraction using a Philips diffractometer. Thermal treatment was carried out at 1.3 Pa as well as in air atmosphere.

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Zusammenfassung Der Polymorphisms von 12CaO·7Al₂O₃ wurde mit Hilfe eines Setaram G-24 Thermoanalysators und durch Röntgenstrukturanalyse mittels eines Philips Diffraktometers untersucht. Die Wärmebehandlung geschah in Luft sowohl bei 1,3 Pa als auch bei Normaldruck.

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-24 12 ·7l₂₃. 1,3 , .