Hunan Provincial Key Laboratory of Environmental Catalysis & Waste Recycling, School of Chemistry and Chemical Engineering, Hunan Institute of Engineering, Xiangtan 411104, China.
Hunan Provincial Key Laboratory of Environmental Catalysis & Waste Recycling, School of Chemistry and Chemical Engineering, Hunan Institute of Engineering, Xiangtan 411104, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2019 May 15;215:9-14. doi: 10.1016/j.saa.2019.02.072. Epub 2019 Feb 20.
The effects of substituent X and Y on ultraviolet (UV) absorption properties of stilbene compounds XPhCHCHPhY (XSBY) were studied both experimentally and computationally from the viewpoint of UV maximum absorption wavelength (λ) and the corresponding energy (υ). In the studies, the contribution of substituents on υ shift was explored. The results show that with increase of electron withdrawing or electron donating ability of X or Y, there is an enhanced electron delocalization of XSBY that leads to bathochromic shift. Computational analyses based on density functional theory were conducted to elucidate the phenomena. It is disclosed that the υ values are significantly affected by the excited state, though the electronic effect of ground state cannot be ignored. Finally, on the basis of the respective influences of X and Y, a quantitative model, which was proved reliable by the leave-one-out method, was developed to scale the effects of terminal substituents on υ. According to the model, the effects of substituents X or Y exhibit almost the same action on υ owing to the symmetric skeleton of the XSBY compounds. The findings provide deep insight into the effects of terminal substituents on UV absorption properties of stilbene compounds, and the derived model enables practical expression of the relationship between substituents and UV absorption.
从紫外最大吸收波长（λ）和相应能量（υ）的角度，通过实验和计算研究了取代基 X 和 Y 对二苯乙烯化合物 XPhCHCHPhY（XSBY）的紫外吸收性质的影响。在这些研究中，探讨了取代基对 υ 位移的贡献。结果表明，随着 X 或 Y 的吸电子或供电子能力的增加，XSBY 的电子离域增强，导致红移。基于密度泛函理论的计算分析阐明了这一现象。结果表明，尽管不能忽略基态的电子效应，但 υ 值受激发态的影响很大。最后，根据 X 和 Y 的各自影响，建立了一个定量模型，该模型通过留一法得到了验证，可用于标度末端取代基对 υ 的影响。根据该模型，由于 XSBY 化合物的对称骨架，取代基 X 或 Y 对 υ 的影响几乎相同。这些发现深入了解了末端取代基对二苯乙烯化合物紫外吸收性质的影响，所得到的模型可以实际表达取代基与紫外吸收之间的关系。
