The stability and aromaticity of thirteen known thymine tautomers were studied in the gas phase at the B3LYP/6-311++G(2d,2p) computational level. It was found that they do not follow the Hückel 4N + 2 rule when the energetic criterion is considered, but they follow it when aromaticity indices, such as NICS, HOMA and the sum of the Wiberg bond indices, are applied. It was shown that the stabilit...

Recently, we discovered that the delocalization of nitrogen lone-pair electrons (NLPEs) in five-membered heterocycles created a second σ-aromaticity addition to prototypical π-aromaticity. Such dual-aromatic compounds, such as pentazole anion, were proved have distinct chemistry comparison traditional π-aromatics, benzene, and surprisingly unstable, susceptible electrophilic attack, relatively ...

Although silicon clusters (Sin) exhibit a diversity of 3-dimensional shapes, a cubic form has not been found to be stable in their small size of 8 Si atoms. While the cubane C8H8 is wellknown for chemists, the octasilacubane Si8H8 possessing a cubic structure has never been synthesized. Using quantum chemical computations we find that doping can lead to stable cubic silicon clusters such as Be@...

The geometries of a series of nine 4-substituted nitrophenols and 4-substituted nitrophenolates (X = H, CONH2, CHO, COOH, COCH3, COCl, CN, NO2, NO) and of their conformers, where the nitro group rotates by 10o from  = 0° to  = 90°, were optimized at the B3LYP/6-311+G** DFT level. These data were used to analyse the effect of rotating of the nitro group on -electron delocalization in the ring...

Dissolved organic matter (DOM) in sediment pore waters from Yangtze estuary of China based on abundance, UV absorbance, molecular weight distribution and fluorescence were investigated using a combination of various parameters of DOM as well as 3D fluorescence excitation emission matrix spectra (F-EEMS) with the parallel factor and principal component analysis (PARAFAC-PCA). The results indicat...

The aromaticity of all possible cyclopenta-fused pyrene congeners has been investigated at various levels of theory. On the basis of the calculated resonance energies and magnetic properties (delta(1)H data, magnetic susceptibility anisotropies, and NICS values), the overall aromaticity of these compounds is found to decrease gradually with increasing number of externally fused five-membered ri...

The chemical importance of the linear response kernel from conceptual Density Functional Theory (DFT) is investigated for some σ and π aromatic and anti-aromatic systems. The effect of the ring size is studied by looking at some well known aromatic and anti-aromatic molecules of different sizes, showing that the linear response is capable of correctly classifying and quantifying the aromaticity...