Effects of the HCN adsorption on the structural and electronic parameters of the beryllium oxide nanotube

The adsorption behavior of the HCN on the surface of beryllium oxide nanotube (BeONT) is studied by the density functional theory. Geometrical parameters, electronic properties and adsorption energies have been calculated for the BeONT and fourteen different HCN configurations on the nanotube. According to the obtained results, the process of the HCN molecule adsorption on different sites on the external surface of the nanotube is exothermic and all of the configurations are stable, while the process of HCN molecule adsorption on the internal surface of the BeONT is endothermic. The adsorption energy values indicate that the HCN molecule can be physically adsorbed on the surface of the BeONT. Furthermore, the HOMO–LUMO gap (Eg) of the BeONT decreases upon the HCN adsorption, resulting in the enhancement of the electrical conductivity. The AIM theory has been also utilized to analyze the properties of the bond critical points: their electron densities and their Laplacians. NBO analysis indicates that the HCN molecule can be adsorbed on the surface of the nanotube with a charge transfer from nanotube to HCN molecule. Due to the physisorption, NQR parameters of nanotube are also altered. In order to examine the deformation degree of the nanotube after HCN molecule adsorption, deformation energy is calculated, which indicates that no significant curvature in the geometry of the nanotubes is occurred when HCN adsorbs onto the surface of BeONT.     

Boosting BeONT Reactivity with HCN by Calcium and Magnesium Doping: A DFT Investigation of Electronic Structure,AIM, NMR,NQR and NBO Analysis

Adsorption of the HCN molecule is very important in environment and industrial applications. The BeONT may be good candidate for HCN capture because of large surface. Unfortunately, BeONT shows limited HCN detection. Therefore, we investigate the possibility of HCN adsorption on Ca and Mg-doped BeONT by density functional theory calculations. It was found that HCN adsorption on doped nanotube has relatively higher adsorption energy as compared with the perfect one. Furthermore, there exists a strong adsorption between HCN molecule and doped nanotubes, which exhibited more active interaction and larger net charge transfer than that of pristine nanotube. As well as, calculated geometrical parameters and electronic properties for studied systems indicate that the Ca-doped BeONT and Mg-doped BeONT present high sensitivity to HCN, compared with the pristine BeONT. Theoretical results reveal that the adsorption of the HCN on the doped nanotube is influenced on the electronic conductance of the doped-BeONT. Therefore, Ca and Mg-doped nanotube can be considered as promising sensor for detecting HCN molecule. According to NBO analysis, electron flow is spontaneous from doped nanotube to HCN molecule.     

Covalent Functionalization of Pristine and Ga-Doped Boron Phosphide Nanotubes with Imidazole

Abstract

Density functional theory (DFT) calculations at the B3LYP/6–31G* level were performed to investigate covalent functionalization of imidazole on pristine (in gas and H₂O phases) and Ga-doped BPNT models in terms of energetic, geometric, and electronic properties. The results show that imidazole, as a functional group, prefers to be adsorbed via its nitrogen atom on the pristine, Ga_B, and Ga_P nanotube models. The adsorption energy of imidazole on the (6,0) zigzag BPNT in gas and solvent phases is ?0.76 and ?1.11 eV, respectively, and about 0.38 and 0.43 electron are transferred from the imidazole to nanotube in the phases. The presence of a polar solvent increases the electron donor of imidazole molecule. The results show that Ga doping can significantly enhance the adsorption energy of imidazole on the nanotube models to about 95%.

Moreover, the imidazole adsorption on the pristine and Ga-doped BPNT models has not significant changes in the energy gap of the nanotube models and it is slightly changed after covalent functionalization process. This study may provide new insight to the development of functionalized boron phosphide nanotubes for generation of the new hybrid compounds especially in drug delivery systems for virtual applications.     

Interaction of isoniazid drug with the pristine and Ni-doped of (4, 4) armchair GaNNTs: a first principle study

In this research, the interaction of isoniazid drug (INH) with the pristine and Ni-doped Gallium nitride nanotubes (GaNNTs) is investigated by using density function theory. The adsorption energy, deformation energy, natural bond orbital (NBO), quantum parameters, molecular electrostatic potential (MEP) and thermodynamic parameters of all adsorption models are calculated from optimized structures. The values of adsorption energy, enthalpy and Gibbs free energy of all adsorption models are negative and all adsorption process are favorable in view of thermodynamic points. It is notable that Ni-doped decrease adsorption strength and it is not suitable for INH adsorption on the GaNNTs surface. The MEP, NBO and maximum amount of electronic charge ΔN results demonstrate that the negative potential are localized around adsorption position and the positive potential are localized around INH molecule. The calculated results indicate that the GaNNTs is a good candidate to making absorber and sensor for detecting INH drug.     

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.     

Fullerene(C_(60)) as a Potential Chemical Sensor for Hydrogen Cyanide Detection

To find a novel sensor for the detection and control of toxic hydrogen cyanide(HCN), the geometrical and electronic parameters of HCN adsorption on fullerene C60 were investigated using density functional theory(DFT) calculations by means of B3 LYP functional with 6-31 G* basis set. The calculated density of states(DOSs) shows that the electronic properties of fullerene C60 were very sensitive to the presence of HCN molecule, so that the Eg of C60 was significantly decreased from 2.76 eV in pristine form to 1.81 eV(34.4% change) after the HCN adsorption which would result in electrical conductance increment. The results demonstrated that the C60 may convert the presence of a HCN molecule to an electrical signal for using in HCN-sensor devices through doping, chemical functionalization. Also, based on calculated results, the C60 is expected to be a potential efficient adsorbent as well as a sensor for detecting the presence of toxic HCN.     

Nitrogen monoxide storage and sensing applications of transition metal–doped boron nitride nanotubes: a DFT investigation

The structural properties, electronic properties, and adsorption abilities for nitrogen monoxide (NO) molecule adsorption on pristine and transition metal (TM = V, Cr, Mn, Nb, Mo, Tc, Ta, W, and Re) doping on B or N site of armchair (5,5) single-walled boron nitride nanotube (BNNT) were investigated using the density functional theory method. The binding energies of TM-doped BNNTs reveal that the Mo atom doping exhibits the strongest binding ability with BNNT. In addition, the NO molecule weakly interacts with the pristine BNNT, whereas it has a strong adsorption ability on TM-doped BNNTs. The increase in the adsorption ability of NO molecule onto the TM-doped BNNTs is due to the geometrical deformation on TM doping site and the charge transfer between TM-doped BNNTs and NO molecule. Moreover, a significant decrease in energy gap of the BNNT after TM doping is expected to be an available strategy for improving its electrical conductivity. These observations suggest that NO adsorption and sensing ability of BNNT could be greatly improved by introducing appropriate TM dopant. Therefore, TM-doped BNNTs may be a useful guidance to be storage and sensing materials for the detection of NO molecule.

     

Effects of heteroatoms on the electronic,sensor, and adsorption properties of graphene

The effects of doping heteroatoms on the structure, electronic and adsorption properties of graphene are investigated using density functional theory calculations. Six different doped graphenes (with Al, B, Si, N, P, and S) are considered, and to obtain the interaction and adsorption properties, three sulfur-containing molecules (H₂S, SO₂, and thiophene) were interacted with selected graphenes. The adsorption energies (E _ad) in the gas phase and solvents show the exothermic interaction for all complexes. The maximum E _ad values are observed for aluminum doped graphene (AG) and silicon doped graphene (SiG), and adsorption energies in the solvent are not so different from those in the gas phase. NBO calculations show that the AG and SiG complexes have the highest E ⁽²⁾ interaction energies and simple graphene (G) and nitrogen doped graphene (NG) have the least E ⁽²⁾ energies. Population analyses show that doping heteroatoms change the energy gap. This gap changes more during the interaction and these changes make these structures useful in sensor devices. All calculated data confirm better adsorption of SO₂ by graphenes versus H₂S and thiophene. Among all graphenes, AG and then SiG are the best adsorbents for these structures.     

Vibrational energies,bonding nature,electronic properties,spectroscopic investigations and analysis of 3-bromo-4-Chlorobenzophenone

In this present study, we investigated pharmaceutically active of 3-Bromo-4-chlorobenzophenone. Structural, electronic properties (HOMO-LUMO, MEP) are investigated using DFT tool. Vibrational spectral analysis for FT-IR and FT-Raman are made of headline molecule. Electronic transition properties are discussed with the help of UV–Vis spectral analysis. Biologically active sites are found from MEP analysis. Electron delocalization properties are studied explored from HOMO-LUMO band gap energy. Moreover, intra molecular interactions are explained from NBO method. Molecular docking studies are performed to find the interactions various pathologies. The topological properties of the electron density have been analyzed.     

Theoretical Investigation of Adsorption Effects of Granisetron Anticancer Drug over BN(7,7-7) Nanotube as a Factor of Drug Delivery: a DFT Study

In the present work, the interaction between drug Granisetron(GRS) and BN(7,7-7) nanotube by density functional theory(DFT) calculations in the solvent water has been investigated. The non-bonded interaction effects of the molecule GRS with BN(7,7-7) nanotube on chemical shift tensors, natural charge and electronic properties such as the energy gap between HOMO and LUMO, global hardness, electronegativity and electronic chemical potential have been also detected. The natural bond orbital(NBO) analysis suggested that charge transfer depended between GRS and nanotube and induces a dipole moment in the complex. Then, the possibility of the use of BN(7,7-7) nanotube for GRS delivery to the diseased cells has been established.     

电场对(4, 0)Zigzag模型单壁碳纳米管的影响

The structural and electronic properties of a (4, 0) zigzag single-walled carbon nanotube (SWCNT) under parallel and transverse electric fields with strengths of 0-1.4×10~(-2) a.u. Were studied using the density functional theory (DFT) B3LYP/6-31G~* method. Results show that the properties of the SWCNT are dependent on the external electric field. The applied external electric field strongly affects the molecular dipole moments. The induced dipole moments increase linearly with increase in the electrical field intensities. This study shows that the application of parallel and transverse electric fields results in changes in the occupied and virtual molecular orbitals (Mos) but the energy gap between the highest occupied MO (HOMO) and the lowest unoccupied MO (LUMO) of this SWCNT is less sensitive to the electric field strength. The electronic spatial extent (ESE) and length of the SWCNT show small changes over the entire range of the applied electric field strengths. The natural bond orbital (NBO) electric charges on the atoms of the SWCNT show that increase in the external electric field strength increases the separation of the center of the positive and negative electric charges of the carbon nanotube.     

DFT study on the structural and electronic properties of Pt-doped boron nitride nanotubes

First-principles calculations based on density functional theory were carried out to investigate the structural and electronic properties of Pt substitution-doped boron nitride (BN) nanotubes. The electronic and structural properties were studied for substituted Pt in the boron and the nitrogen sites of the (BN) nanotube. The band gap significantly diminishes to 2.095 eV for Pt doping at the B site while the band gap diminishes to 2.231 eV for Pt doping at the N site. The band density increases in both the valence band and the conduction band after doping. The effects of the hardness and softness group 17 (halogen elements) were calculated by density functional theory (DFT).     

Adsorption of hydrogen molecules on the platinum-doped boron nitride nanotubes

Adsorption of hydrogen molecules on platinum-doped single-walled zigzag (8,0) boron nitride (BN) nanotube is investigated using the density-functional theory. The Pt atom tends to occupy the axial bridge site of the BN tube with the highest binding energy of -0.91 eV. Upon Pt doping, several occupied and unoccupied impurity states are induced, which reduces the band gap of the pristine BN nanotube. Upon hydrogen adsorption on Pt-doped BN nanotube, the first hydrogen molecule can be chemically adsorbed on the Pt-doped BN nanotube without crossing any energy barrier, whereas the second hydrogen molecule has to overcome a small energy barrier of 0.019 eV. At least up to two hydrogen molecules can be chemically adsorbed on a single Pt atom supported by the BN nanotube, with the average adsorption energy of -0.365 eV. Upon hydrogen adsorption on a Pt-dimer-doped BN nanotube, the formation of the Pt dimer not only weakens the interaction between the Pt cluster and the BN nanotube but also reduces the average adsorption energy of hydrogen molecules. These calculation results can be useful in the assessment of metal-doped BN nanotubes as potential hydrogen storage media.     

First-principles investigation of the electronic and field emission properties of C-doped ZnO nanotube

In order to search for novel field emitter nanomaterial, a density functional theory investigation is performed to understand electronic structures and field emission properties of carbon doped–ZnO nanotube. It has been revealed that electron transport through ZnONT is significantly increased in the presence of the carbon atom due to the reduced HOMO–LUMO energy gap, which makes the electrons easily excited from HOMO to LUMO, and then the electrons can easily emit. Comparing the ionization potentials of the pure and doped ZnONT, at the same external electric field strength, the ionization potential of C–doped ZnO nanotube is lower than that of pure one. Also, after the doping of carbon atom, the Fermi level of ZnONT increases, which indicates that the Fermi level shifts toward the conduction band. These results indicate that the field emission properties of ZnONT can be enhanced by the doping of ZnO nanotube with the carbon atom.     

DFT studies on global parameters,antioxidant mechanism and molecular docking of amlodipine besylate

Amlodipine besylate (AMB) is a synthetic dihydropyridine calcium channel blocker with antihypertensive and anti-anginal effects. Quantum computational investigations on AMB were done using DFT/B3LYP/6-311++G (d, p) level of theory, to study the molecular structural properties, nonlinear properties and antioxidant properties of AMB. The electrophilic and nucleophilic sites along with complete NBO analysis helps to locate the intermolecular electronic interactions and their stabilization energies. Complete NBO analysis was additionally done to locate the intermolecular electronic interactions and their stabilization energies. Charge distributions of Mulliken population, NBO and MEP are correlated. Also, the antioxidant properties of AMB were assessed to check whether these antioxidant effects contribute to the effects of antioxidant therapy. Further, the molecular docking studies of these compounds demonstrated a good selectivity profile with Monoamine oxidase B with better binding affinity and confirms AMB is a potent antioxidant.     

Dispersion-corrected DFT study on the carbon monoxide sensing by B<Subscript>2</Subscript>C nanotubes: effects of dopant and interferences

Electrical sensitivity of a boron carbon nanotube (B₂CNT) 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 H₂O, H₂S and NH₃ cannot significantly change the electronic properties of B₂CNT. Therefore, the Si-doped tube might convert the presence of CO molecules to electrical signal.     

A theoretical study of potential energy surface and some chemo-physical descriptors of Aspirin,Coupling the rotation of the ester and carboxyl groups

In this paper, the effect of the simultaneous rotation of the carboxyl (COOH) and ester (R'COOR) functional groups on the potential energy surface (PES) of aspirin is studied. Relative energies are reported at the HF/aug-cc-pVDZ and B3LYP/aug-cc-pVDZ levels of theory. To understand the activity and selected electrophilic attack sites, electric dipole moments, atomic charges, HOMO-LUMO energy gap, natural bond orbital (NBO), and molecular electrostatic potential (MEP) analyses, as well as the main structural parameters of the identified conformers, are studied at the same theoretical level. Finally, an NBO analysis is used to demonstrate charge transfer between lone pairs and localized bonds.     

Formaldehyde adsorption on the interior and exterior surfaces of CN nanotubes

Using density functional theory, we have investigated the adsorption of formaldehyde (H₂CO) on the interior and exterior walls of a carbon nitride nanotube (CNNT) in terms of energetic, geometric, and electronic properties. It was found that the adsorption is more preferential on the exterior surface of the tube with maximum adsorption energy of ?7.4 kcal/mol. It has also been found that the adsorption energy per molecule is increased by increasing the number of adsorbed molecules. The results reveal that the electronic properties of CNNT are very sensitive to the presence of formaldehyde so that the HOMO/LUMO gap is reduced from 4.02 eV in the free tube to 2.44 eV in the most stable configuration of 3H₂CO/CNNT complex. Also, we have showed that the response of the tube may depend on concentration of the H₂CO molecules, suggesting that the CNNT might produce an electrical signal in the presence of H₂CO molecules.