B12N12 Nano-cage as Potential Sensor for NO2 Detection

The NO₂ molecule adsorption on B₁₂N₁₂ nano-cage was investigated using density func-tional theory calculations in terms of adsorption energy, HOMO/LUMO energy gap (Eg) changes, charge transfer, structural deformation, etc. Furthermore, some aspects of stability and properties of B₁₂N₁₂ including calculation of binding electronic and Gibbs free energies, density of states, and molecular electrostatic potential surfaces are investigated. Three pos-sible configurations for NO₂ adsorption on the B₁₂N₁₂ nano-cage are energetically found. Interestingly, the results reveals that the Eg of B₁₂N₁₂ cluster is very sensitive to the pres-ence of NO₂ molecules as its value reduces from 6.84 eV in free cluster to 3.23 eV in the most stable configuration of NO₂/cluster complex. This phenomenon dramatically increases the electrical conductivity of the cluster, suggesting that the B₁₂N₁₂ nano-cluster may be potential sensor for NO₂ gaseous molecule detection.     

O3 and SO2 sensing concept on extended surface of B12N12 nanocages modified by Nickel decoration: A comprehensive DFT study

Adsorption of SO₂ and O₃ molecules on pristine boron nitride (B₁₂N₁₂) and Ni-decorated B₁₂N₁₂ nano-cages has been systemically investigated through density functional theory (DFT) methods. Adsorption energies (thermodynamics), bond distances, charge analysis, dipole moments, orbital analysis and density of states are calculated by van der Waals DFT method (MPW1PW91) functional. The adsorption energies of O₃ and SO₂ on pristine B₁₂N₁₂ are about −143.8 and −14.0 kJ mol⁻¹, respectively. The interaction energies of O₃ and SO₂ with pristine B₁₂N₁₂ are indicative of chemisorption and physisorption, respectively. Ni-decorated B₁₂N₁₂ (Ni@BN) enhances adsorption of both O₃ and SO₂ species. The interaction energies for adsorption of SO₂ are about −166 and −277 kJ mol⁻¹ whereas the corresponding energies for O₃ are −362 and −396 kJ mol⁻¹ for configuration A and B, respectively. These observations show that functionalized B₁₂N₁₂ are highly sensitive toward SO₂ and O₃ molecules.     

BN Nanotube Serving as a Gas Chemical Sensor for N<Subscript>2</Subscript>O by Parallel Electric Field

Density functional theory calculations were performed to understand the electronic properties of C₂₄, B₁₂N₁₂, B₁₂P₁₂, and (6, 0) BNNT interacted with N₂O molecule in the presence and absence of an external electric field using the B3LYP method and 6-31G** basis set. The adsorption of N₂O from O-side on the surface of (6, 0) BNNT has high sensitivity in comparison with B₁₂N₁₂ nano-cage. The adsorption energy of N₂O (O-side) on the sidewalls of B₁₂N₁₂ and BNNT in the presence of an electric field are ?21.01 and ?15.48 kJ mol^?1, respectively. Our results suggest that in the presence of an electric field, the B₁₂N₁₂ nano-cage is the more energetically notable upon the N₂O adsorption than (6, 0) BNNT, C₂₄, and B₁₂P₁₂. Whereas, our results indicate that the electronic property of BNNT is more sensitive to N₂O molecule at the presence of an electric field than B₁₂N₁₂ nano-cage. It is anticipated that BNNT could be a favorable gas sensor for the detection of N₂O molecule.     

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.     

The properties and possible transformation path for C12B24N24

The structure and frequencies of C₁₂B₂₄N₂₄ have been calculated by means of an ab initio method. By comparing the average bond energies with C₆₀, the calculated results predict that the cage C₁₂B₂₄N₂₄ is a stable molecule. The calculated results indicate that the cage molecule C₁₂B₂₄N₂₄ has a relative large HOMO–LUMO energy gap and a low rigidity. The structures and stability of six possible isomers of C₂B₄N₄ are used to suggest a possible transformation path from the pentagon CB₂N₂ to the C₁₂B₂₄N₂₄ materials. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 363–368, 2001     

A DFT study on electronic and optical properties of aspirin-functionalized B<Subscript>12</Subscript>N<Subscript>12</Subscript> fullerene-like nanocluster

In this work, the interaction of an aspirin (AS) molecule with the external surface of a boron nitride fullerene-like nanocage (B₁₂N₁₂) is studied by means of density functional theory (DFT) calculations. Equilibrium geometry, electronic properties, adsorption energy and thermodynamic stability are identified for all of the adsorbed configurations. Four stable configurations are obtained for the interaction of AS molecule with the B₁₂N₁₂ nanocage, with adsorption energies in the range of ?10.1 to ?37.7 kcal/mol (at the M06-2X/6-31 + G** level). Our results clearly indicate that Al-doping of the B₁₂N₁₂ tends to increase the adsorption energy and thermodynamic stability of AS molecule over this nanocage. We further study the adsorption of AS over the B₁₂N₁₂ and B₁₁N₁₂Al in the presence of a protic (water) or aprotic (benzene) solvent. It is found that the calculated binding distances and adsorption energies by the PCM and CPCM solvent models are very similar, especially for the B₁₂N₁₂ complexes. According to time-dependent DFT calculations, the Al-doping can shift estimated λ _max values toward longer wavelengths (redshift). Solvent effects also have an important influence on the calculated electronic absorption spectra of AS-B₁₂N₁₂ complexes.     

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.     

Si‐Doped B12N12 Nanocage as an Adsorbent for Dissociation of N2O to N2 Molecule

Adsorption of N₂O molecule by using density functional theory calculations at the B3LYP/6–31G* level onto pristine and Si‐doped B₁₂N₁₂ nanocage in terms of energetic, geometric, and electronic properties was investigated. The results of calculations showed that the N₂O molecule is physically adsorbed on the pristine and Si‐doped B₁₂N₁₂ (Si_N) models, releasing energies in the range of –1.13 to –2.02 kcal mol⁻¹. It was found that the electronic properties of the models have not changed significantly upon the N₂O adsorption. On the other hand, the adsorption energy of N₂O on the Si‐doped B₁₂N₁₂ (Si_B model) was about –67.20 kcal mol⁻¹and the natural bond orbital charge of 0.58|e| is transferred from the nanocage to the N₂O molecule. In the configuration, the O atom of N₂O molecule is bonded to the Si atom of the nanocage, so that an N₂ molecule escapes from the wall of the nanocage. The results showed that the Si_B model can be an adsorbent for dissociation of the N₂O molecule.     

A Density Functional Investigation of Fluorinated B12N12 Clusters

Density functional calculations have been carried out on a series of fluorinated B₁₂N₁₂ molecules. The fluorine atoms are more prone to absorb on the boron atoms than the nitrogen atoms in B₁₂N₁₂. The 1,3 addition is an energetically favorable adsorption site in one‐fluorine‐molecule adsorption. We found that the average bond energy of fluorine molecule is decreased with n increasing, but significantly larger than that of B₁₂N₁₂F. The energy gap of B₁₂N₁₂ is controllable by introducing fluorine molecules. Moreover, calculation of the Gibbs free energy of the B₁₂N₁₂+12F₂→B₁₂N₁₂F₂₄ reaction showed that this reaction is exothermic at low temperatures.     

Etude stereochimique de l'alkylation d'anions par des derives p-nitrobenzyliques optiquement actifs : Competition SN2-SNR1

Competition between S_RN1,S_N2 and S_RN1 mechanisms is discussed according to the stereochemical results in the alkylation of anions by optically active secondary p-nitrobenzyl reagents. Results from alkylation of the anions of benzylcyanide C and α-aminonitrile A by p-nitrobenzyl chloride 2 rule out S_N2 and S_RN2 mechanisms. On the other hand, the S_N2 process becomes exclusive in O-and C-alkylation of the acetoacetic ester anion B by the p-nitrobenzyl phosphonium salt, and this result shows that it is possible to obtain p-nitrobenzyl alkylation products without racemisation. C-Alkylation of the anion B by halide 2 involves an S_N2-electron transfer competition. The whole result illustrates that the stereochemical method provides precise information on the mechanism of these reactions.     

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.     

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.     

Theoretical study of isomerism, structure, and stability of dimers of C-doped aluminide clusters (C@Al12)2 and (C@Al12)(L@Al12) (L = Si, Ge)

The geometric, energetic, and vibrational characteristics of the dimers of carbon-doped aluminum clusters (C@Al₁₂)₂, (C@Al₁₂)(Si@Al₁₂), and (C@Al₁₂)(Ge@Al₁₂) have been calculated by ab initio density functional theory B3LYP method with the basis sets 6-31G* and 6-311+G*. As distinct from the silicon and germanium analogues (Si@Al₁₂)₂ and (Ge@Al₁₂)₂ with an AA lowest-lying structure, in which the Si@Al₁₂ and Ge@Al₁₂ blocks retain the shape of distorted icosahedra A, the symmetric AA structure is not typical of the (C@Al₁₂)₂ dimer (itcorresponds to a transition state) and the most favorable structures are two closely spaced BB and AD isomers, in which the C@Al₁₂ blocks have either a distorted icosahedral (A) or nonicosahedral geometry (B, a dicapped ten-vertex polyhedron; D, a marquee with a centered hexagonal base). The calculated energy of dissociation of the most favorable isomer AD into isolated C@Al₁₂ (I _h ) monomers is ～45 kcal/mol, which is 1.5–2 times as large as the corresponding dissociation energy of (Si@Al₁₂)₂ and (Ge@Al₁₂)₂. For mixed dimers of the (C@Al₁₂)(L@Al₁₂) type with L = Si or Ge, three types of low-lying isomers (AA, BA, and DA) are predicted in which the Si@Al₁₂ and Ge@Al₁₂ blocks retain their shape A and the C@Al₁₂ blocks have geometry A, B, and D, respectively. For all the isomers, the block-block bonds are comparable in length and energy to the bonds inside the blocks and have the same chemical nature. Specific features of the geometry, relative stability, ionization potentials, electron affinity, vibrational spectra, and other characteristics of doped aluminide dimers, which could be used for the identification of their isomers by spectroscopic methods, are discussed.     

Cathodic behaviour of [*η-C3H5)Pd(Ph2P-C2H4-PPh2)] in acetonitrile solution: an electrochemical process involving very fast consecutive chemical reactions

The cathodic reduction of [(η³-C₃H₅)Pd(Ph₂P-C₂H₄-PPh₂)]⁺, A, in acetonitrile solution affords Pd(Ph₂P-C₂H₄-PPh₂)₂, B, and Pd(η³-C₃H₅)₂, C. Its cyclic voltammetric behaviour is studied as a function of scan rate and concentration of A. These results and relevant coulometric experiments indicate a primary reversible charge transfer reaction followed by a fast second order process producing P₁ and P₂. This picture is complicated by a subsequent reaction of B with A leading to a dimeric electroactive species which is reduced at a slightly more negative potential value than A. The rate constants of individual chemical reactions were evaluated by digital simulation and best fit with experimental results.     

A semiempirical study of C24N4 and its boron-nitrogen analogs

The results of semiempirical calculations on the heterofullerence C₂₄N₄ and its boron-nitrogen analogs B₆N₁₀C₁₂ (the smallest CBN ball) are presented in accordance with considerations of chemical bondings and geometries. The structures and relative properties of the 28-atom cages, C₂₈, C₂₄N₄, and B₆N₁₀C₁₂, were investigated using semiempirical methods contained in the MOPAC program. C₂₄N₄ and B₆N₁₀C₁₂ have T_d and C₃ symmetry, respectively. B₆N₁₀C₁₂ has four geometric isomers, and their optimized structures were determined. The ionization energies, vibrational frequencies, IR intensities, and various thermodynamic properties (including entropy and heat capacity) for C₂₄N₄ and B₆N₁₀C₁₂ were calculated by the MNDO method. The evidence suggests that a B₆N₁₀C₁₂ cage is more stable than that of C₂₄N₄. Possible experimental methods to prepare B₆N₁₀C₁₂ are also proposed. © 1996 John Wiley & Sons, Inc.     

Pseudobrookite mit weitgehend geordneter Metallverteilung: CoTi2O5, MgTi2O5 und FeTi2O5

(A), (B) and (C) were prepared by solid state reactions. Single crystals of quenched samples were examined by X-ray investigation. On the opposite of A₂TiO₅-pseudobrookite compounds (A), (B) and (C) crystallize with a high ordered metaldistribution on the point positions 4c and 8f.     

Influence of NO2 attachment on the nuclear magnetic shielding tensors of N and B nuclei in C30B15N15 heterofullerene: a DFT study

Adsorption of nitrogen dioxide in three different configurations on the exterior surface of C₃₀B₁₅N₁₅ is studied using density functional theory calculations. To this end, we optimized the structures of raw C₃₀B₁₅N₁₅ and nine NO₂–C₃₀B₁₅N₁₅ complexes at the B3LYP/6-31G^* level of theory and then calculated chemical shielding (CS) tensors at the GIAO-B3LYP/6-311G^** level for the optimized structures. The calculated chemical shielding isotropy (CSI), chemical shielding anisotropy (CSA), and orientation of CS tensors (Euler angles) reveal that the adsorption configurations (nitro, trans-nitrite, and cis-nitrite) have different effects on the electronic structure of C₃₀B₁₅N₁₅. Natural atomic charges based on natural population analysis (NPA) were used to justify the changes in CSI values after gas sorption.     

The applications of near-infrared Fourier transform Raman spectroscopy to the analysis of polymorphic forms of cimetidine

Fourier transform (FT)-Raman spectroscopy, utilizing a near-infrared (Nd:YAG laser, at 1.064 μm) source was used to characterise the three anhydrous polymorphic forms A, B and C of the drug cimetidine (N″-cyano-N-methyl-N′ -[2-[(5-methyl-1H-imidazol-4-yl) methylthio]ethyl]guanidine). The FT-Raman spectra were free from fluorescence interference and had good signal-to-noise ratios. Each polymorph has a distinct spectrum, characterised by two regions, 1250-1050 cm⁻¹ and 1500-1350 cm⁻¹. This work demonstrates that it is possible to use FT-Raman spectroscopy to differentiate between polymorphic forms of the same compound.     

Tricyclic ligands on cyclam core and X-ray crystallographic structure of hexachloro-(1,11:4,8-bis(pyridine-2,6-diyl-bis(2-(N-(2-formidoylethylene)carbamoyl)ethylene))-1,8-diazonia-4,11-diazacyclotetradecane) - dimanganese(II) dimethanol dihydrate solvate

The synthesis of tricyclic compounds on functionalized cyclam core is described. The addition of four methyl acrylate molecules and consecutive condensation of this derivative with ethylenediamine resulted in formation of 1,4,8,11-tetrakis(2-(N-(2-aminoethyl)carbamoyl)ethyl)-1,4,8,11-tetraazacyclotetradecane (3). Compound 3 was the substrate for further condensation with dialdehydes: iso-phthaldialdehyde and 2,6-pyridinedicarbaldehyde, resulting in spontaneous macrocycle ring closure to give tricyclic derivatives: 1,11:4,8-bis(benzene-1,3-diyl-bis(2-(N-(2-formidoylethylene)carbamoyl)ethylene))-1,4,8,11-tetraazacyclotetradecane (4) in the reaction of 3 with iso-phthaldialdehyde and three isomers: 1,4:8,11-bis(pyridine-2,6-diyl-bis(2-(N-(2-formidoylethylene)carbamoyl)ethylene))-1,4,8,11-tetraazacyclotetradecane (5A), 1,11:4,8-bis(pyridine-2,6-diyl-bis(2-(N-(2-formidoylethylene)carbamoyl)ethylene))-1,4,8,11-tetraazacyclotetradecane (5B), and 1,8:4,11-bis(pyridine-2,6-diyl-bis(2-(N-(2-formidoylethylene)carbamoyl)ethylene))-1,4,8,11-tetraazacyclotetradecane (5C) when 2,6-pyridinedicarbaldehyde was used. The compounds 4, 5B, and 5C were identified crystallographically. The isolated 5A converted in solution into the mixture of 5B and 5C as monitored by the ¹H NMR spectroscopy. The tricycle 5 is able to accept two manganese(II) metal ions by reacting with manganese(II) dichloride with simultaneous diprotonation of 5. Structure of the resulting Mn₂(5BH₂)Cl₆·(CH₃OH)₂(H₂O)₂ was determined crystallographically.     

Adsorption of the nitrosamine and thionitrosamine molecules as carcinogen compounds on the BN and B3Al N nanotubes: A DFT study

DFT calculations were performed to investigation of the influence of doping three atoms of aluminum on the electronic properties of the (4,0) zigzag boron nitride nanotube (BNNT). Also, adsorption properties of nitrosamine (NA) and thionitrosamine (TNA) molecules as carcinogen agents onto BN and B_Al3N nanotubes were studied. The results show that the B_3AlN nanotube is the most energetically favorable candidates for adsorption of these molecules. Also, B(B_3Al)NNT/TNA complexes are more stable than B(B_3Al)NNT/NA complexes. The HOMO–LUMO gap, electronic chemical potential (μ), hardness (?), softness (S), the maximum amount of electronic charge (ΔN_max) and electrophilicity index (ω) for monomers and complexes in the gas and polar solvent phases were calculated. The results show that the conductivity and reactivity of BNNT increase by doping Al atoms instead of B atoms. Also, the interaction of NA and TNA molecules with BN and B_Al3N nanotubes results in significant changes in the electronic properties of nanotubes. Based on the natural bond orbital (NBO) analysis, in all complexes charge transfer occurs from NA and TNA molecules to nanotubes. Theory of atoms in molecules (AIM) was applied to characterize the nature of interactions in nanotubes. It is predicted that, BN and B_3AlN nanotubes can be used to as sensor for detection of NA and TNA molecules.