To investigate the substituent effect on x-electron delocalization of the N-benzylideneaniline （NBA）, the vertical resonance energies △E^V（θ） of eleven substituted NBAs were separated into n and a parts at the B...To investigate the substituent effect on x-electron delocalization of the N-benzylideneaniline （NBA）, the vertical resonance energies △E^V（θ） of eleven substituted NBAs were separated into n and a parts at the B3LYP/6-311G（d） level of the Density Functional Theory （DFT）. When substituted with an electron-releasing group --OH, the calculated △E^V（θ） of NBA was increased, indicative of more resonance destabilization than the mother molecule. However, when substituted with an electron-withdrawing group -NO2, the calculated △E^V（θ） values indicated less resonance destabilization. The most destabilizing effect was observed especially when the -OH group located at the ortho-position of the aromatic ring in the fragment -N=CH-Ar. For most of the substituted NBA molecules, it was the destabilized a framework that determined the destabilizing feature of the vertical resonance energy, instead of the stabilized n system. When the -NO2 substituent at the para-position of the aromatic ring of the -N=CH-Ar group, the π system had the highest stabilizing effect while the σ framework exhibited the highest destabilizing effect. While the -NO2 substituent was at the para-position of the left aromatic ring （At-）, the NBA had the least vertical resonance energy value.展开更多
基金Project supported by the National Natural Science Foundation of China （No. 204720feng88）.
文摘To investigate the substituent effect on x-electron delocalization of the N-benzylideneaniline （NBA）, the vertical resonance energies △E^V（θ） of eleven substituted NBAs were separated into n and a parts at the B3LYP/6-311G（d） level of the Density Functional Theory （DFT）. When substituted with an electron-releasing group --OH, the calculated △E^V（θ） of NBA was increased, indicative of more resonance destabilization than the mother molecule. However, when substituted with an electron-withdrawing group -NO2, the calculated △E^V（θ） values indicated less resonance destabilization. The most destabilizing effect was observed especially when the -OH group located at the ortho-position of the aromatic ring in the fragment -N=CH-Ar. For most of the substituted NBA molecules, it was the destabilized a framework that determined the destabilizing feature of the vertical resonance energy, instead of the stabilized n system. When the -NO2 substituent at the para-position of the aromatic ring of the -N=CH-Ar group, the π system had the highest stabilizing effect while the σ framework exhibited the highest destabilizing effect. While the -NO2 substituent was at the para-position of the left aromatic ring （At-）, the NBA had the least vertical resonance energy value.
