A DFT studies on a potential anode compound for Li-ion batteries: Hexa-cata-hexabenzocoronene nanographen

In this work, the possible apply of a hexa-cata-hexabenzocoronene HCor as anode material was studied for Li-ion batteries (LIBs) using the B3LYP/6-31G* level. The planar structure of HCor is less stable (by about 0.243 hartree) in comparison with the twisted structure. The Li cation and neutral are suitably adsorbed high up the middle of a HCor hexagonal ring with the adsorption energy of -120.3 and -2.7 kcal/mol, respectively. The calculated specific storage capacity of HCor is 450.1 mAh/g and the great cell voltage is 2.63 V generated by the interaction between Li+ and HCor. The HCOR is considered an ideal candidate to be used as an anode material in LIBs because of high storage capacity and ion mobility

The strengthening effect of a hydrogen or lithium bond on the Z···N aerogen bond (Z = Ar, Kr and Xe): a comparative study

<p>An <i>ab initio</i> study is performed on O₃Z···NCM···NCX (Z = Ar, Kr and Xe; M = H and Li; X = H, F and CH₃) complexes to investigate cooperativity effects between aerogen and hydrogen or lithium bonding interactions in these systems. To understand the cooperative effects, a detailed analysis of the binding distances, interaction energies and bonding properties is performed on these complexes. The results indicate that all Z···N and H/Li···N binding distances in the ternary complexes are shorter than those of corresponding binary systems. For a given M or X, cooperative energies increase as Z = Xe > Kr > Ar. Moreover, O₃Z···NCLi···NCX complexes exhibit a larger cooperative energy than O₃Z···NCH···NCX ones. The non-covalent interaction (NCI) index analysis indicates that the formation of an H/Li···N interaction in the ternary complexes shifts the location of the spike associated with the Z···N interaction towards the negative λ₂ρ values. This indicates that NCI analysis can be regarded as a useful tool for the study of cooperative effects between two different non-covalent interactions. Also, cooperative effects in O₃Z···NCM···NCX complexes make a decrease in ¹⁴N nuclear quadrupole coupling constants of NCH or NCLi molecule.</p> <p></p

A novel multicomponent reaction between amino acids, aromatic aldehydes and p-toluenesulfonylmethyl isocyanide: an efficient and green one-pot synthesis using nanosilica

The novel diastereomeric sulfonylamide derivatives 4a–h were synthesized by multi-component reactions between (l)-α-amino acids, 1, aromatic aldehydes, 2 and p-toluenesulfonylmethyl isocyanide, 3 in water/methanol using nanosilica as a catalyst. The one-pot green reactions were carried out at room temperature with a quantitative yield in water/methanol. The yield of the reactions and products was determined and discussed. The reusablity of the catalyst is discussed

A Novel Four-Component Reaction between Secondary Amines and Hydroxybenzaldehydes with Isocyanides in Water: An Efficient One-Pot and Green Synthesis of Benzo[b]furan Derivatives

The novel benzo[b]furan derivatives, 7a–i, were synthesized and characterized by Ugi four-component reaction between 2-hydroxybenzaldehyde derivative 1, a secondary amine 2, and an isocyanide 3 in water. Those reactions were carried out at room temperature with moderate to good yields in one pot

Symmetric bifurcated halogen bonds: substituent and cooperative effects

<p>The aim of this study is to investigate the geometries, interaction energies and bonding properties of the symmetrical bifurcated halogen bond interactions (BXBs) by means of <i>ab initio</i> calculations. For this purpose, the NCX (X = Cl, Br) molecule is paired with a series of N-formyl formamide (NFF) derivatives (NFF-Z, Z = H, CN, CCH, OH, CH₃ and Li), and the properties of the resulting complexes are studied by molecular electrostatic potential, quantum theory of atoms in molecules, noncovalent interaction index and natural bond orbital analyses. For a fixed NCX molecule, interaction energies increase in the order of Z = Li > CH₃ > H > OH > CCH > CN. We found a strong correlation between the interaction energies of NCX:NFF-Z complexes and molecular electrostatic potential minimum values associated with NFF-Z monomers. Moreover, cooperative effects between BXB and XċċċN halogen bond interactions are studied in the ternary NCX:NCX:NFF-Z systems. Our results indicate that the strength of BXB interactions in the ternary complexes is enhanced by the presence of XċċċN bonds. Besides, cooperativity effects tend to increase the covalency of BXBs in these systems.</p

An <i>ab initio</i> study on substituent and cooperative effects in bifurcated fluorine bonds

<p>Bifurcated fluorine bond (BFB) interactions are studied in model binary complexes pairing N-formyl formamide derivatives and FX molecules (X = F, CN, NC, CF₃ and CCH) by means of <i>ab initio</i> calculations. The calculated F···O binding distances in these complexes are in the range of 2.813–3.048 Å. The corresponding interaction energies lie in a narrow range, from−2.25 to −16.49 kJ/mol. The nature of BFBs is analysed by a vast number of methods including molecular electrostatic potential, quantum theory of atoms in molecules, non-covalent interaction index and natural bond orbital methods. According to the energy decomposition analysis, the electrostatic and dispersion effects have a dominant role in the formation of these complexes. The formation of a hydrogen- and lithium-bonding interaction tends to increase the strength of BFBs in the ternary XF:NFF-H:NH₃ and XF:NFF-Li:NH₃ complexes, respectively.</p

An <i>ab initio</i> study on the nature of σ-hole interactions in pnicogen-bonded complexes with carbene as an electron donor

<p>A theoretical study of the complexes formed between ZH₂X (Z = P, As, Sb, Bi; X = F, Cl, Br, CN, NC, OH, NH₂) and an <i>N</i>-heterocyclic carbene (imidazol-2-ylidene) is carried out by means of <i>ab initio</i> calculations. According to molecular electrostatic potential analysis, it is inferred that the divalent C atom of the carbene can act as a Lewis base with the pnicogen atom Z of ZH₂X. The pnicogen bond distances (Z–C) are in the range of 2.050–2.911 for these complexes. While the Z−X bonds are longer than the corresponding Z−C bonds in the X = Cl and Br complexes, most of the Z−X bonds are short enough to suggest that they should be considered as covalent bonds which have lost some degree of covalency. For a given Z, the ZH₂Br forms the strongest complex, followed by ZH₂Cl and ZH₂F. On the other hand, the binding energy in the halogenated ZH₂X complexes follows the reverse ranking expected based on the values of the σ-hole of the isolated ZH₂X monomers. The nature of the pnicogen bond interaction in these complexes is analysed by quantum theory of atoms in molecules (QTAIM) and natural bond orbital methods. According to QTAIM analysis, a partially covalent character can be attributed to the pnicogen bonds studied here.</p> <p></p