Spectroscopic analysis and DFT calculations of a food additive Carmoisine

The spectroscopic (FT-IR, FT-IR gas phase, FT-Raman and UV) and NBO analysis of 4-Hydroxypiperidine by density functional method.

Application of common duckweed (Lemna minor) in phytoremediation of chemicals in the environment: State and future perspective.

Experimental and CIS, TD-DFT, ab initio calculations of visible spectra and the vibrational frequencies of sulfonyl azide-azoic dyes.

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, 13C, 1H, UV) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 4-[(4-aminobenzene) sulfonyl] aniline by ab initio HF and density functional method

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 OWFπ-π (the relationship between π-π overlap weighting factor) value than by the TD-DFT method. The method of regression showing the linear relationship between OWFπ-π and BLN-N (nitrogen-nitrogen bond lengths) as OWF π-π=−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).

Study on the prediction of visible absorption maxima of azobenzene compounds

In order to predict the absorption half-band width, the ground state and the first singlet-excited state configurations of some azobenzene compounds are calculated by B3LYP/6-311G* and CIS methods, respectively. Based on the configurations obtained above, the absorption maximum and emission maximum are calculated by TD-DFT method, the results are in good agreement with observed values. Further study shows a linear relationship between Δ λ 1/2 (the observed absorption half-band width) and S (the difference between the emission maximum and absorption maximum). According to the relationship obtained, the absorption half-band width of other azobenzene derivatives in the same series could be predicted successfully.

Jun-na Liu

Papers

Study on the prediction of visible absorption maxima of azobenzene compounds

Research on the prediction of absorption half-band width of some azobenzene compounds