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. 2005 Jun;6(6):584-9.
doi: 10.1631/jzus.2005.B0584.

Study on the prediction of visible absorption maxima of azobenzene compounds

Jun-na Liu  1 , Zhi-rong Chen, Shen-feng Yuan
Affiliations

Study on the prediction of visible absorption maxima of azobenzene compounds

Jun-na Liu et al. J Zhejiang Univ Sci B. 2005 Jun.

Abstract

The geometries of azobenzene compounds are optimized with B3LYP/6-311G* method, and analyzed with nature bond orbital, then their visible absorption maxima are calculated with TD-DFT method and ZINDO/S method respectively. The results agree well with the observed values. It was found that for the calculation of visible absorption using ZINDO/S method could rapidly yield better results by adjusting OWF(pi-pi) (the relationship between pi-pi overlap weighting factor) value than by the TD-DFT method. The method of regression showing the linear relationship between OWF(pi-pi) and BL(N-N) (nitrogen-nitrogen bond lengths) as OWF(pi-pi)=-8.1537+6.5638BL(N-N), can be explained in terms of quantum theory, and also be used for prediction of visible absorption maxima of other azobenzne dyes in the same series. This study on molecules' orbital geometry indicates that their visible absorption maxima correspond to the electron transition from HOMO (the highest occupied molecular orbital) to LUMO (the lowest unoccupied molecular orbital).

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Figures

Fig. 1
Fig. 1
The general structure of azobenzene dyes
Fig. 2
Fig. 2
The optimized geometries based on B3LYP/6-311G* method The compounds 1–8 are in accordance with Tables 1, 2 and 3
Fig. 3
Fig. 3
The relationship between OWF π-π and BL N-N
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