The Rand Z-substituent effects for the gas-phase thermal decompositions of carbamates, R2NC(=O)OCH2CH2Z, have been investigated theoretically at B3LYP level with 6-31G(d) and 6-31++G(d,p) basis sets. Both the Zand R-substituent effects on reactivity (ΔH≠) were well consistent with experimental results, although the R-substituent effect was underestimated theoretically. No correlations were foun...

A series of benzene derivatives with different substituents adsorbed on graphene was investigated using a density-functional tight-binding method with a dispersion correction. Compared to benzene, the derivative with either an electron-withdrawing or -donating substituent exhibits stronger physisorption. Moreover, the steric size of the substituent is important in determining the adsorption str...

The mechanofluorochromism is related to the optical properties according electron push–pull substituent effect. As intramolecular charge transfer decreases, strong intermolecular interactions occur, leading mechanofluorochromism.

To understand better the impact of donor-acceptor substitution on the properties of linearly π-conjugated compounds, we performed a computational study on a series of variably substituted trans-polyacetylenes, polyynes, and polythiophenes. The focus of this work is on how rapidly the impact of a given substituent or a given combination of substituents vanishes along the π-conjugated chain. The ...

Twelve 3-cyano-4-(substituted phenyl)-6-phenyl-2(1H)-pyridinones were investigated by tandem mass spectrometry using positive as well as negative electrospray ionization. The influence of the electron affinity of the substituent and the steric effect on the fragmentation is discussed. Pyridinones with a substituent of low proton affinity show loss of water, HCN or benzene from the pyridinone ri...

Conformational analyses on 2-substituted (methoxy, vinyloxy, and acetoxy) methylenecyclohexanes have been performed computationally with HF, B3LYP, PBE0, and MP2 and the 6-31G(d) basis set. The global minimum for the methoxy substituent is an axial conformer. For the vinyloxy substituent, except with PBE0, an axial conformer is determined as the global minimum. The acetoxy substituent prefers t...

ab initio calculations were employed to investigate nitrogen inversion as a configuration change that can supply an infinitely useful switchable control mechanism for some complex systems. in this paper, design of a new artificial molecular nanohinge is discussed based on nitrogen inversion in which reciprocating motion of substituent in effect of inversion phenomenon, led to an open–close moti...

The 70 ev positive and negative ion mass spectra of ring-substituted nitrobenzenes were studied. The influence of the substituent group on the fragmentation modes of the molecular ions is discussed. The effect of pressure in the formation of negative ions was also studied. As expected, the ratio of fragment ions to negative molecular ions decreased with increasing pressure in ion source.

Benzodiazepines are useful drugs for treatment of sleep disorders, anxiety, seizure cases and skeletal muscle cramps. Some derivatives of 2-(2-Phenoxy) phenyl-1, 3, 4-oxadiazole were synthesized as benzodiazepine receptor agonists. Conformational analysis and superimposition of energy minima conformers of the compounds on estazolam, a known benzodiazepine agonist, reveal that the main proposed ...