Acta Phys. -Chim. Sin. ›› 2017, Vol. 33 ›› Issue (4): 729-735.doi: 10.3866/PKU.WHXB201611291

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Extension and Application of Excited-State Constants of meta-Substituents

Qian ZHU,Chao-Tun CAO,Chen-Zhong CAO*()   

  • Received:2016-10-13 Published:2017-03-23
  • Contact: Chen-Zhong CAO
  • Supported by:
    The project was supported by the National Natural Science Foundation of China(21272063);The project was supported by the National Natural Science Foundation of China(21672058);Scientific Research Fund of Hunan Provincial Education Department, China(14C0466);Natural Science Foundation of Hunan Province, China(湖南省自然科学基金)


Seven series of 3, 4'-disubstituted stilbenes were synthesized, with meta-substituents X (m-XSBYp) including: NO2, I, CHCH2, Ph, Et, NMe2, and CCH (m-XSBY-p). The longest wavelength maximum λmax (nm) in ultraviolet absorption spectra of the compounds were measured. A quantitative correlation analysis was performed in terms of energy, the Vmax (cm-1) for 3, 4'-disubstituted stilbenes. The excited-state substituent constants σCC (m)exof the seven meta-substituents were determined by curve-fitting. The constants σCCexof the metaand para-substituents were compared with their Hammett constants σ. The results indicated that σCCexand σ express the substituent electrostatic effects in the excited-and ground-states, respectively. In addition, 10 samples of aryl Schiff bases and 14 samples of 3, 3'-disubstituted stilbenes with meta-substituents X were synthesized, and their λmax, pred. were predicated based on the obtained constants σCC (m)ex. These results showed that the λmax, pred. values agreed well with the experimental values, and confirmed the reliability of the obtained σCC (m)exvalues. We also collected Vmax values of 225 samples of disubstituted stilbenes and disubstituted benzenes and established a general quantitative equation to express the change regularity of their Vmax.

Key words: Excited-state substituent constant, meta-Substituent, Ultraviolet absorption spectrum, Stilbene, Aryl Schiff base


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