Formation of sandwich and multidecker complexes between O2 and alkali/alkaline earth metals: A DFT study

Abstract: Feasibility of formation of sandwich and multidecker complexes between O2 molecules and alkali/alkaline earth metal has been analyzed in the light of density functional theory (DFT). High value of...

Role of heteroatoms and substituents on the structure, reactivity, aromaticity, and absorption spectra of pyrene: a density functional theory study

Effect of heteroatoms viz. BN and substituents viz. –Me (methyl), –OH (hydroxyl), –NH2 (amine), –COOH (carboxyl), and –CN (cyano) on the structural parameters, global reactivity, aromaticity, and UV-visible spectra of pyrene are studied with the help of density functional theory (DFT). Global reactivity parameters such as global hardness (η) and electrophilicity (ω) are calculated using density functional reactivity theory (DFRT). Time dependent density functional theory (TD-DFT) is explored for interpreting the UV-visible absorption spectra. Aromaticity of the pyrene rings are predicted from the nucleus independent chemical shift (NICS) values. Presence of BN unit and substituent induces reasonable impact on the studied parameters. The observed absorption spectra lie predominantly within the UV-region (both blue and red shifts are observed in presence of BN and substituent). HOMO energy and absorption spectra are affected nominally in solvent phase.

Quantitative Assessment of B-B-B, B-Hb -B, and B-Ht Bonds: From BH3 to B12 H12 2

We report the thermodynamic stabilities and the intrinsic strengths of three-center-two-electron B-B-B and B-H_b -B bonds ( H b : bridging hydrogen), and two-center-two-electron B-H_t bonds ( H t : terminal hydrogen) which can be served as a new, effective tool to determine the decisive role of the intermediates of hydrogenation/dehydrogenation reactions of borohydride. The calculated heats of formation were obtained with the G4 composite method and the intrinsic strengths of B-B-B, B-H_b -B, and B-H_t bonds were derived from local stretching force constants obtained at the B3LYP-D2/cc-pVTZ level of theory for 21 boron-hydrogen compounds, including 19 intermediates. The Quantum Theory of Atoms in Molecules (QTAIM) was used to deepen the inside into the nature of B-B-B, B-H_b -B, and B-H_t bonds. We found that all of the experimentally identified intermediates hindering the reversibility of the decomposition reactions are thermodynamically stable and possess strong B-B-B, B-H_b -B, and B-H_t bonds. This proves that thermodynamic data and intrinsic B-B-B, B-H_b -B, and B-H_t bond strengths form a new, effective tool to characterize new (potential) intermediates and to predict their role for the reversibility of the hydrogenation/dehydrogenation reactions.

Density Functional Study on the Adsorption of 5-Membered N-Heterocycles on B/N/BN-Doped Graphene: Coronene as a Model System

Adsorption of seven 5-membered N-heterocycles on B/N/BN-doped graphene (with coronene as a model system) has been studied using density functional theory (DFT). The geometry of the complexes validated the involvement of both π···π stacking and N-H···π interaction in the adsorption process. The stability of the complexes is measured in terms of stabilization energy, and the results suggested that the complexes are stable enough (stabilization energies are in the range of 7.61-14.77 kcal mol^-1). Studies confirmed the stability of complexes in the solvent phase too irrespective of the dielectric of the solvent. Dispersive force is the major mode of interaction in stabilizing the complexes. Natural bond orbital analysis indicated a small contribution from electrostatic and covalent interactions. Thermochemical analysis revealed that the complexation is exothermic in nature and favorable at a lower temperature. Adsorption of N-heterocycles exerts a nominal impact on the electronic properties of the undoped/doped graphene. The study presents a simple approach to introduce an arbitrary functionality to undoped/doped graphene by preserving its electronic properties.

Amphiphiles without Head-and-Tail Design: Nanostructures Based on the Self-Assembly of Anionic Boron Cluster Compounds

Anionic boron cluster compounds (ABCCs) are intrinsically amphiphilic building blocks suitable for nanochemistry. ABCCs are involved in atypical weak interactions, notably dihydrogen bonding, due to their peculiar polyhedral structure, consisting of negatively charged B-H units. The most striking feature of ABCCs that differentiates them from typical surfactants is the lack of head-and-tail structure. Furthermore, their structure can be described as intrinsically amphiphilic or aquaneutral. Therefore, classical terms established to describe self-assembly of classical amphiphiles are insufficient and need to be reconsidered. The opinions and theories focused on the solution behavior of ABCCs are briefly discussed. Moreover, a comparison between ABCCs with other amphiphilic systems is made focusing on the explanation of enthalpy-driven micellization or relations between hydrophobic and chaotropic effects. Despite the unusual structure, ABCCs still show self- and coassembly properties comparable to classical amphiphiles such as ionic surfactants. They self-assemble into micelles in water according to the closed association model. The most typical features of ABCCs solution behavior is demonstrated on calorimetry, NMR spectroscopy, and tensiometry experiments. Altogether, the unique features of ABCCs makes them a valuable inclusion into the nanochemisty toolbox to develop novel nanostructures both alone and with other molecules.

On the formation of sandwich and multidecker complexes via π⋯π interaction: a DFT study

Sandwich and multidecker complexes via organic π–inorganic π interaction.

Sandwiches of N-doped diamondoids and benzenevialone pair–cation and cation–pi interaction: a DFT study

Cation–lone pair and cation–pi interactions in the complexes of N-doped dimondoids.