共查询到20条相似文献,搜索用时 586 毫秒
1.
In this work, the interaction of an aspirin (AS) molecule with the external surface of a boron nitride fullerene-like nanocage (B 12N 12) 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 B 12N 12 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 B 12N 12 tends to increase the adsorption energy and thermodynamic stability of AS molecule over this nanocage. We further study the adsorption of AS over the B 12N 12 and B 11N 12Al 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 B 12N 12 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-B 12N 12 complexes. 相似文献
2.
Predicting adsorption behavior of the Triacanthine (TRC) anticancer drug on the surface of B 12N 12 nano-cage was investigated using DFT and TD-DFT methods by B3LYP/6-311+G(d) level in the water solution. The adsorption energies of the TRC-B 12N 12 complexes ( A- C) were shown that the adsorption process is exothermic. The UV/Vis absorption and IR spectra analysis were calculated to investigate the changes happening in adsorption of TRC over nano-cage. According to the results, the interaction of the TRC drug from the N9 atom on the B 12N 12 nano-cage (model A) has the most chemical stability rather than models B and C. Based on NBO analysis, the charge transfer process has happened between the TRC drug and B 12N 12 nano-cage. Recovery time, charge difference (ΔN), and ELF analysis were calculated. It was understood that the B 12N 12 nano-cage can be a good carrier for the delivery of TRC anticancer medicine. 相似文献
3.
The NO 2 molecule adsorption on B 12N 12 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 B 12N 12 including calculation of binding electronic and Gibbs free energies, density of states, and molecular electrostatic potential surfaces are investigated. Three pos-sible configurations for NO 2 adsorption on the B 12N 12 nano-cage are energetically found. Interestingly, the results reveals that the Eg of B 12N 12 cluster is very sensitive to the pres-ence of NO 2 molecules as its value reduces from 6.84 eV in free cluster to 3.23 eV in the most stable configuration of NO 2/cluster complex. This phenomenon dramatically increases the electrical conductivity of the cluster, suggesting that the B 12N 12 nano-cluster may be potential sensor for NO 2 gaseous molecule detection. 相似文献
4.
The interaction of hydrazine (N 2H 4) molecule with pristine and Si-doped aluminum nitride (Al 12N 12) nano-cage was investigated using the density functional theory calculations. The adsorption energy of N 2H 4 on pristine Al 12N 12 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 N 2H 4 and Al 12N 12 nano-cage, N 2H 4 molecule exhibits high sensitivity toward Si-doped Al 12N 12 nano-cage so that the energy gap of the Si-doped Al 12N 12 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 N 2H 4 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 Al 12N 11 is anticipated to be a potential novel sensor for detecting the presence of N 2H 4 molecule. 相似文献
5.
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 (SiN) 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 (SiB 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 SiB model can be an adsorbent for dissociation of the N2O molecule. 相似文献
6.
The absorption feasibility of benzene molecule in the C 24, Si@C 24, Si-doped C 24, and C 20 fullerenes has been studied based on calculated electronic properties of these fullerenes using Density functional Theory (DFT). It is found that energy of benzene adsorption on C 24, Si@C 24, and Si-doped C 24 fullerenes were in range of –2.93 and –51.19 kJ/mol with little changes in their electronic structure. The results demonstrated that the C 24, Si@C 24, and Si-doped C 24 fullerenes cannot be employed as a chemical adsorbent or sensor for benzene. Silicon doping cannot significantly modify both the electronic properties and benzene adsorption energy of C 24 fullerene. On the other hand, C 20 fullerene exhibits a high sensitivity, so that the energy gap of the fullerene is changed almost 89.19% after the adsorption process. We concluded that the C 20 fullerene can be employed as a reliable material for benzene detection. 相似文献
7.
Excitation of electronic states of the N 2 molecule by electron impact is recognized as an essential process in nitrogen plasmas that strongly impacts their chemical reactivity and other properties. Many surface and coating technologies are based on radio-frequency plasma discharges in nitrogen. In this paper the electron impact excitation rate coefficients for singlet and triplet electronic states of the N 2 molecule have been calculated in non-equilibrium conditions in the presence of a radio-frequency electric field. A Monte Carlo simulation has been performed in order to determine non-equilibrium electron energy distribution functions within one period of the electric field. By using these distribution functions, the excitation rate coefficients have been obtained in the frequency range from 13.56 up to 500 MHz, at reduced electric field values from 200 to 700 Td. 相似文献
8.
The complex [UO 2(SeO 4)(C 5H 12N 2O) 2(H 2O)] ( I) was synthesized and studied by thermal analysis, IR spectroscopy, and X-ray crystallography. The crystals are orthorhombic: a = 13.1661(3) Å, b = 16.4420(5) Å, c = 17.4548(6) Å, Pbca, Z = 8, R = 0.0423. The structural units of crystal I are chains with the composition coinciding with that of the compounds of the AB 2M 3 1 crystal chemical group of the uranyl complexes (A = UO 2 2+ , B 2 = SeO 4 2? , M 1 = C 5H 12N 2O and H 2O). 相似文献
9.
In this present study, the adsorption behavior of HO 2 radical on the exterior surface of (5, 0) zigzag boron nitride nanotube (BNNT) has been investigated. The electronic structures and geometries of studied complexes were calculated at B3LYP-D3/6-31++G (d, p) computational level. The value of adsorption energy for the most stable configuration ( A) is obtained ?0.68 eV, indicating physisorption process. Meaningful change of HOMO–LUMO gap after adsorption confirming BNNT can be introduced as a promising sensor for sensing of HO 2 radical. 相似文献
10.
Two new heteropolyoxovanadoborates (H 2dap) 2H 6{(VO) 12O 6[B 3O 6(OH)] 6(H 2O)}·13H 2O ( 1, dap = 1,2-diaminopropane) and {[Zn(dien)] 2[Zn(dien)(H 2O)] 4(VO) 12O 6[B 3O 6(OH)] 6(H 2O)} 2·15H 2O ( 2, dien = diethylenetriamine) have been hydrothermally synthesized and structurally characterized. Both 1 and 2 contain {(VO) 12O 6[B 3O 6(OH)] 6(H 2O)} cluster (denoted on V 12B 18), which is constructed by a puckered B 18O 36(OH) 6 ring sandwiched between two triangles of six alternating cis and trans edge-sharing vanadium atoms, and a central water molecule. 1 consists of discrete [V 12B 18] 10− cluster anions with H 2dap 2+ as counterions, while 2 consists of discrete neutral {[Zn(dien)] 2[Zn(dien)(H 2O)] 4[V 12B 18]} clusters, which are built from two types of zinc(II) complex fragments connecting with V 12B 18 cluster through two Zn-( μ
3-O)-B bonds. Interestingly, 2 is the only example of the V 12B 18 cluster decorated by two types of zinc(II) complex fragments. 相似文献
11.
The adsorption of H 2O and D 2O on porous polymers, Chromosorb-102 (styrene-divinylbenzene copolymer) and MN-200 (supercross-linked polystyrene), was studied by gas chromatography. Test adsorbates used to study the properties of the surface of these polymers were n-alkanes (C 6-C 9), C 6H 6, and the polar compounds CHCl 3, CH 3NO 2, CH 3CN, (CH 3) 2CO, C 2H 5COOCH 3, and (C 2H 5) 2O. The experimental data on the retention of the sorbates were used to determine the contributions of dispersion and specific intermolecular interactions to the total energy of adsorption for the systems studied. The electron donor K D and electron acceptor K A characteristics of the surfaces of Chromosorb-102 and MN-200 were determined. The K D and K A values obtained allow these polymers to be classified as weakly specific adsorbents with the predominance of electron acceptor properties. The adsorption isotherms of H 2O and D 2O were measured at 55, 67, and 80°C. The dependences of the isosteric heats of adsorption Q st on adsorption values were determined. The conclusion was drawn that H 2O interacted with the surface of the polymers by the adsorption mechanism, whereas absorption likely made a noticeable contribution to the retention of D 2O. 相似文献
12.
The title compound, [Co(C 6H 13)(C 11H 19N 4O 2)(H 2O)]ClO 4, is in the general class of coenzyme B 12 models which contain a ClO 4 anion and a [Co(C 6H 13)(C 11H 19N 4O 2)(H 2O)] + cation. In the cation, the Co atom has a distorted octahedral coordination, with the n‐hexyl and H 2O ligands in axial positions. The crystal data reveal some degree of flexibility in the Costa‐type system, which is similar to the coenzyme B 12. 相似文献
13.
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. 相似文献
14.
The quasi-ternary system Tl 2Se-AgTlSe-TlBiSe ( A) has been investigated by DTA, X-ray powder diffraction, microstructural analysis, and microhardness measurements. Polythermal sections AgTlSe-TlBiSe 2, AgTlSe-Tl 9BiSe 6, [Ag 0.5Tl 1.5Se]-TlBiSe 2, Tl 2Se-AgBiSe 2 (0–50 mol % AgBiSe 2), an isothermal section at 500 K, and the projection of the liquidus surface of system A have been constructed. It has been shown that the quasi-binary join AgTlSe-Tl 9BiSe 6 divides system A into two subordinate triangles, namely, Tl 2Se-Tl 9BiSe 6-AgTlSe ( B) and AgTlSe-Tl 9BiSe 6-TlBiSe 2 ( C). The phase diagram of subsystem B involves a univariant eutectic equilibrium while subsystem C involves an invariant eutectic equilibrium. The ternary eutectic has the coordinates 650 K, 10 mol % TlBiSe 2, and 61 mol % AgTlSe. A continuous series of solid solutions (0–12 mol % AgTlSe) has been found along the Tl 2Se-Tl 9BiSe 6 bordering system. The homogeneity region of TlBiSe 2 extends to 5 mol %. 相似文献
15.
The doping of graphene molecules by borazine (B 3N 3) units may modify the electronic properties favorably. Therefore, the influence of the substitution of the central benzene ring of hexa‐ peri‐hexabenzocoronene (HBC, C 42H 18) by an isoelectronic B 3N 3 ring resulting in C 36B 3N 3H 18 (B3N3HBC) is investigated by computational methods. For comparison, the isoelectronic and isosteric all‐B/N molecule B 21N 21H 18 (termed BN) and its carbon derivative C 6B 18N 18H 18 (C6BN), obtained by substitution of a central B 3N 3 by a C 6 ring, are also studied. The substitution of C 6 in the HBC molecule by a B 3N 3 unit results in a significant change of the computed IR vibrational spectrum between 1400 and 1600 cm ?1 due to the polarity of the borazine core. The properties of the BN molecule resemble those of hexagonal boron nitride, and substitution of the central B 3N 3 ring by C 6 changes the computed IR vibrational spectrum only slightly. The allowed transitions to excited states associated with large oscillator strengths shift to higher energy upon going from HBC to B3N3HBC, but to lower energy upon going from BN to C6BN. The possibility of synthesis of B3N3HBC from hexaphenylborazine (HPB) using the Scholl reaction (CuCl 2/AlCl 3 in CS 2) is investigated. Rather than the desired B3N3HBC an insoluble and X‐ray amorphous polymer P is obtained. Its analysis by IR and 11B magic angle spinning NMR spectroscopy reveals the presence of borazine units. The changes in the 11B quadrupolar coupling constant CQ, asymmetry parameter η, and isotropic chemical shift δiso( 11B) with respect to HPB are in agreement with a structural model that includes B3N3HBC‐derived monomeric units in polymer P. This indicates that both intra‐ and intermolecular cyclodehydrogenation reactions take place during the Scholl reaction of HPB. 相似文献
16.
Electrical sensitivity of a boron carbon nanotube (B 2CNT) was examined toward carbon monoxide (CO) molecule by using dispersion-corrected density functional theory calculations. It was found that CO is weakly adsorbed on the tube, releasing energy of 3.5–4.1 kcal/mol, and electronic properties of the tube are not significantly changed. To overcome this problem, boron and carbon atoms of the tube were substituted by aluminum and silicon atoms, respectively. Although both Al and Si doping make the tube more reactive and sensitive to CO, Si doping seems to be a better strategy to manufacture CO chemical sensors due to the higher sensitivity without deformation of nanotube structure after adsorption procedure. Moreover, it was shown that some interference molecules such as H 2O, H 2S and NH 3 cannot significantly change the electronic properties of B 2CNT. Therefore, the Si-doped tube might convert the presence of CO molecules to electrical signal. 相似文献
17.
Starting from the paddlewheel complex copper(II)acetate, the green N-methylimidazole adduct of copper(II)acetate is formed
and transformed into the monomeric and dimeric N-methylimidazole adducts of copper(II)acetate [Cu(C 4H 6N 2) 2(CH 3COO) 2] n·xH 2O (n = 1,2; x = 0, 6). The formation of the blue dimer or the purple monomer depends on the solvent and the presence or absence
of water. 相似文献
18.
Oxazolidin‐2‐ones are widely used as protective groups for 1,2‐amino alcohols and chiral derivatives are employed as chiral auxiliaries. The crystal structures of four differently substituted oxazolidinecarbohydrazides, namely N′‐[( E)‐benzylidene]‐ N‐methyl‐2‐oxo‐1,3‐oxazolidine‐4‐carbohydrazide, C 12H 12N 3O 3, (I), N′‐[( E)‐2‐chlorobenzylidene]‐ N‐methyl‐2‐oxo‐1,3‐oxazolidine‐4‐carbohydrazide, C 12H 12ClN 3O 3, (II), (4 S)‐ N′‐[( E)‐4‐chlorobenzylidene]‐ N‐methyl‐2‐oxo‐1,3‐oxazolidine‐4‐carbohydrazide, C 12H 12ClN 3O 3, (III), and (4 S)‐ N′‐[( E)‐2,6‐dichlorobenzylidene]‐ N,3‐dimethyl‐2‐oxo‐1,3‐oxazolidine‐4‐carbohydrazide, C 13H 13Cl 2N 3O 3, (IV), show that an unexpected mild‐condition racemization from the chiral starting materials has occurred in (I) and (II). In the extended structures, the centrosymmetric phases, which each crystallize with two molecules ( A and B) in the asymmetric unit, form A+ B dimers linked by pairs of N—H...O hydrogen bonds, albeit with different O‐atom acceptors. One dimer is composed of one molecule with an S configuration for its stereogenic centre and the other with an R configuration, and possesses approximate local inversion symmetry. The other dimer consists of either R, R or S, S pairs and possesses approximate local twofold symmetry. In the chiral structure, N—H...O hydrogen bonds link the molecules into C(5) chains, with adjacent molecules related by a 2 1 screw axis. A wide variety of weak interactions, including C—H...O, C—H...Cl, C—H...π and π–π stacking interactions, occur in these structures, but there is little conformity between them. 相似文献
19.
The structure and frequencies of C 12B 24N 24 have been calculated by means of an ab initio method. By comparing the average bond energies with C 60, the calculated results predict that the cage C 12B 24N 24 is a stable molecule. The calculated results indicate that the cage molecule C 12B 24N 24 has a relative large HOMO–LUMO energy gap and a low rigidity. The structures and stability of six possible isomers of C 2B 4N 4 are used to suggest a possible transformation path from the pentagon CB 2N 2 to the C 12B 24N 24 materials. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 363–368, 2001 相似文献
20.
Adsorption of light and heavy water (H 2O and D 2O) on porous hypercross-linked polystyrene MN-272 was studied by gas chromatography. For the estimation of the properties
of this polymer surface, n-alkanes (C6—C9), C 6
6, and polar compounds (CHCl 3, MeNO 2, MeCN, Me 2CO, EtCOOCH 3, Et 2O) were used as test adsorbates. The contributions of energies of dispersion and specific (donor-acceptor) intermolecular
interactions to the total energy of adsorption were determined on the basis of experimental data on the retention of the sorbates.
The electron-donor and electron-acceptor characteristics of the hypercross-linked polystyrene MN-272 surface were estimated.
Hypercross-linked polystyrene MN-272 was found to be a weakly specific adsorbent with predomination of electron-donating properties.
The adsorption isotherms of H 2O and D 2O were measured on this polymer at 50, 60, and 70 °C. The dependences of the isosteric heats of adsorption on the amount adsorbed
were determined. The contribution of the energy of specific interactions to the total energy of adsorption for all polar adsorbates
(except for acetone, light and heavy water) does not exceed 20%. Adsorption of H 2O on hypercross -linked polystyrene MN-272 is slightly weaker than that of D 2O. 相似文献
|