The nucleus-independent chemical shifts (NICS) and electron density profiles along the inner and outer regions defined by the two stacked aromatic rings of [2.2]paracyclophane have been analyzed and compared to those of free benzene and p-xylene and benzene dimers taken as reference models. It is found that stacked aromatic rings show a reduction of the NICS indicator of aromaticity as compared...

The interplay between aromaticity and hydrogen bonding in 1,3-dihydroxyaryl-2-aldehydes is investigated by means of quantum-chemical calculations. The position of the extra ring formed by substituents interacting through the hydrogen bond (HB) is found to influence both the strength of the HB and the local aromaticity of the polycyclic aromatic hydrocarbon (PAH) skeleton. The HBs are stronger a...

We show that the delocalization indices calculated within the framework of the quantum theory of atoms in molecules provide an excellent basis for the definition of a bond order in polycyclic aromatic hydrocarbons. We show that the two-electron information contained within the delocalization index can be estimated from the electron density at the bond critical point, a mapping that has no a pri...

In this paper, a detailed study of the local aromaticity in a series of cyclopenta-fused linear polyacenes (acenaphthylene derivatives) was performed using several different criteria of aromaticity. Namely, the energy effect (ef), bond resonance energy (BRE), harmonic oscillator model of aromaticity (HOMA) index, multi centre delocalization indices (MCI), electron density at ring critical point...

substitution of two or four carbon atoms by nitrogen in the corannulene molecule as a carbon nanostructure was done and the obtained structures were optimized at mp2/6-31g(d) level of theory. calculations of the nucleus-independent chemical shift (nics) were performed to analyze the aromaticity of the corannulene rings and its derivatives upon doping with n at b3lyp/6-31g(d) level of theory. re...

the armaticity of 5 methylcytosine tautomers in the gas phase has been studied and the chemical structures of related tautomers are investigated . the electronic energy, enthalpy and free energy of each tautomer are also estimated at the b3lyp/6-31 g* // b3lyp/6-31 g* and mp2 / 6-31 g* // mp2 / 6-31 g* levels

The influence of fluorine substitutions on the stability of benzene is examined by using the Hartree-Fock (HF) and MP2 models. It is conclusively demonstrated that homodesmotic reactions based on the open-chain zigzag polyenes are unsatisfactory. A comparison of the intramolecular interactions of educts and products shows that they are not well balanced. Hence, these reactions should be abandon...