On lithium doping in two stable nano-flakes of the B24: The double-ring versus the quasiplanar configuration.

The stable local minima due to the addition of the Li atom to the double-ring and the quasiplanar configurations of the B24 molecule have been searched on the doublet potential energy surface to reveal the structural and electronic features of the Li@B24 system. We report two and seven stable local minima without imaginary vibrational frequency for the Li@B24(double-ring) and the Li@B24(quasiplanar) systems, respectively. The criteria of the adsorption energy, the vertical ionization (VI) energy, the deformation energy, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap, the atomic charges, the spin density distribution, the electron transfer (ET), atoms in molecules (AIM) analysis and the nonlinear optical (NLO) properties have been investigated for all the reported molecules of the Li@B24 system in the present paper. Our results present that both thermodynamic and chemical stability of the Li atom doping to the quasiplanar configuration of the B24 molecule are more than those of the double-ring configuration. Additionally, both the double-ring and the quasiplanar configurations can produce the Li@B24 system with values of high first hyperpolarizability (ßtotal) due to the Li atom doping. In all the reported molecules of the Li@B24 system, electron density of the Li atom decreases due to the existence of the double-ring and the quasiplanar configurations confirming the role of the electron donor for the Li atom. In contrast, both decreasing and increasing electron density have been observed in the B atoms of the Li@B24 system. However, the role of electron acceptor (increasing electron density) for the B atoms is more dominant than the role of electron donor (decreasing electron density). This result highlights chemical flexibility of the B atoms.

A DFT study on graphene, SiC, BN, and AlN nanosheets as anodes in Na-ion batteries.

A great concern exists about the lifetime, cost, low-temperature performance, and safety of Li-ion batteries. Na-ion batteries (NIB) are an alternative to the Li-ion batteries due to the wide availability of sodium, its low cost, and nontoxicity. Here, we examined the Na and Na+ adsorption on nanosheets of carbon (graphene), AlN, BN, and SiC to explore their potential use as an anode in NIBs. The interaction of atomic Na was found to play the main role in producing different nanosheet cell voltages. Unlike the graphene and SiC nanosheets, the lone pairs on the surface of the AlN and BN nanosheets hinder the Na adsorption and significantly increase the cell voltage. The order of magnitude of the nanosheet cell voltage as an anode in NIBs is as follows: AlN (1.49 V) > BN (1.46 V) > > C (0.69 V) > SiC (0.61 V). The AlN and BN nanosheets may be appropriate compounds for NIBs and their cell voltages are comparable with carbon nanotubes.

N-Propargylamines: versatile building blocks in the construction of thiazole cores.

Thiazoles and their hydrogenated analogues are not only key structural units in a wide variety of natural products but they also constitute important building blocks in medicinal chemistry. Therefore, the synthesis of these compounds using new protocols is always interesting. It is well known that N-propargylamines can undergo a number of cyclization reactions to produce various nitrogen-containing heterocycles. In this review, we highlight the most important developments on the synthesis of thiazole and its derivatives starting from N-propargylamines. This review will be helpful in the development of improved methods for the synthesis of natural and biologically important compounds.

A DFT study on the central-ring doped HBC nanographenes.

Nanographenes (NGs) are a segment of graphene whose dangling bonds are saturated with hydrogen atoms, introducing different properties and promising applications. Here we investigate the electronic, thermodynamic, optical, and structural properties of four C36X3Y3H18 NGs (X=B, and Al; and Y=N, and P) based on the density functional theory calculations. It was mainly found that 1) BN-NG is planar molecule and the others are buckybowl-shaped ones, 2) The bowl-to-bowl inversion Gibbs free energies (ΔG#) of buckybowl shaped NGs are very huge and the rate constant is very small, hindering the inversion, 3) The relative energetic stability order based on the standard enthalpy of formation (ΔHf°) is as BN>AlN>BP>AlP, which the BN, and AlN doped NGs are stable at room temperature but the BP and AlP doped ones are instable, 4) The electrical conductivity order of magnitude is inverse of that of stability, 5) An exciton binding energy is predicted in the range of 0.57-0.75eV for the NGs which corresponds to Frenkel exciton type, 6) the NGs are not soluble in organic solvent in agreement with the experimental results and is partially soluble in water solvent with Gibbs free energy of solvation (ΔGsolv) in the range of -6.1 to -10.1kcal/mol.

Selective detection of cyanogen halides by BN nanocluster: a DFT study.

The electronic sensitivity and adsorption behavior toward cyanogen halides (X-CN; X = F, Cl, and Br) of a B12N12 nanocluster were investigated by means of density functional theory calculations. The X-head of these molecules was predicted to interact weakly with the BN cluster because of the positive σ-hole on the electronic potential surface of halogens. The X-CN molecules interact somewhat strongly with the boron atoms of the cluster via the N-head, which is accompanied by a large charge transfer from the X-CN to the cluster. The change in enthalpy upon the adsorption process (at room temperature and 1 atm) is about -19.2, -23.4, and -30.5 kJ mol-1 for X = F, Cl, and Br, respectively. The LUMO level of the BN cluster is largely stabilized after the adsorption process, and the HOMO-LUMO gap is significantly decreased. Thus, the electrical conductivity of the cluster is increased, and an electrical signal is generated that can help to detect these molecules. By increasing the atomic number of X, the signal will increase, which makes the sensor selective for cyanogen halides. Also, it was indicated that the B12N12 nanocluster benefits from a short recovery time as a sensor.

Na-ion batteries based on the inorganic BN nanocluster anodes: DFT studies.

It has been recently indicated that the Li-ion batteries may be replaced by Na-ion batteries because of their low safety, high cost, and low-temperature performance, and lack of the Li mineral reserves. Here, using density functional theory calculations, we studied the potential application of B12N12 nanoclusters as anode in Na-ion batteries. Our calculations indicate that the adsorption energy of Na+ and Na are about -23.4 and -1.4kcal/mol, respectively, and the pristine BN cage to improve suffers from a low cell voltage (∼0.92V) as an anode in Na-ion batteries. We presented a strategy to increase the cell voltage and performance of Na-ion batteries. We showed that encapsulation of different halides (X=F-, Cl-, or Br-) into BN cage significantly increases the cell voltage. By increasing the atomic number of X, the Gibbs free energy change of cell becomes more negative and the cell voltage is increased up to 3.93V. The results are discussed based on the structural, energetic, frontier molecular orbital, charge transfer and electronic properties and compared with the performance of other nanostructured anodes.

Experimental and theoretical study on diethyl-(Z)-2-(5,7-diphenyl-1,3,4-oxadiazepin-2-yl)-2-butenedioate using different levels of computational methods.

In this research work, diethyl-(Z)-2-(5,7-diphenyl-1,3,4-oxadiazepin-2-yl)-2-butenedioate, 7, was synthesized and characterized by FT-IR, 1H NMR, 13C NMR spectroscopy, elemental analyses and mass spectra. The reliabilities of various ab initio methods including HF and B3LYP were evaluated. The bond lengths, bond angles, dihedral angles, charge density on atoms at 7 were calculated. The ab initio calculations indicated that the B3LYP method with a 6-311++G(d,p) basis set can give accurate results. The 13C NMR and 1H NMR chemical shifts of 7 calculated and compared with the related experimental data. The HOMO, LUMO, molecular electrostatic potential (MEP) of 7 were investigated. The thermodynamic parameters and physico-chemical properties were calculated.

One-pot synthesis, FT-IR, NMR and density functional method (B3LYP) studies on 2-(cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate.

2-(Cyclohexylamino)-2-oxo-1-(pyridin-2-yl)ethyl benzoate has been synthesized and characterized by elemental analysis, FT-IR, (1)H NMR and (13)C NMR. Geometrical structures, vibrational frequencies, (1)H and (13)C chemical shift values, molecular electrostatic potential maps and several thermodynamic parameters of title compound in the ground state have been calculated by using the density functional method with 6-31G(d) basis set. The IR spectrum of title compound was interpreted in terms of potential energy distribution (PED) analysis and NMR chemical shifts were also simulated using the GaussView program. Comparison of the theoretical vibrational spectra, (1)H and (13)C NMR chemical shifts of title compound showed a good agreement with the experimental data.