According to Johnstone(1991), there are three level of chemistry: macroscopic level, symbolic level, and sub-microscopic level. Students find chemistry difficult, especially with the sub-microscopic level, when they cannot transfer from one level to another. In addition, students participating in th...
According to Johnstone(1991), there are three level of chemistry: macroscopic level, symbolic level, and sub-microscopic level. Students find chemistry difficult, especially with the sub-microscopic level, when they cannot transfer from one level to another. In addition, students participating in the R&E(Research and Education) program have difficulties in making selection of topics, so they often progress their professor’s research as it is. I think that something is needed to stimulate students' intellectual curiosity, and azo dye could be a good topic for students. It has been widely used as a synthetic dye, and recently researches are being conducted in various fields such as a photosensor and a reducing agent. Therefore, we aimed to conduct experiments on photoisomerization and spectroscopic properties of azo dye and confirm this by DFT calculation.
The experiments of photoisomerization phenomenon of azobenzene, the experiments of color change of azo violet by pH, and the experiments of complex formation with azo violet and Mg2+ and the change of colors made the students have the intellectual curiosity of azo dye.
After that, theoretical DFT / TD-DFT calculation of azo dye was carried out. In this research, we confirmed the mechanism of the photoisomerization phenomenon of azobenzene based on the Potential Energy Surface (PES) of azobenzene we calculated. We also investigated the tautomerization mechanism of azo violet based on its PES. To understand the color change of azobenzene and azo violet due to substituents, the energy levels of HOMO and LUMO by substituents were calculated. We can see that the energy levels of HOMO and LUMO increase as the substituents are changed by NO2, CN, H, OH, NH2. It is confirmed that azo dye is in visible ray area by calculating the band gap. In order to know the complex formation and color change of azo violet and metal ions (M2+ = Mg, Ca, Mn, Fe, Zn), energy levels of HOMO and LUMO by metal ions were calculated. The calculation result showed that the energy levels of HOMO and LUMO increase as the period of the metal increases, and the energy levels of HOMO and LUMO increase mostly as the atomic number increases in the same period.
In this way, the color change of azo dye was confirmed by DFT / TD-DFT calculation. This research can be applied appropriately to school lessons or R&E program, adapted according to the level of students.
According to Johnstone(1991), there are three level of chemistry: macroscopic level, symbolic level, and sub-microscopic level. Students find chemistry difficult, especially with the sub-microscopic level, when they cannot transfer from one level to another. In addition, students participating in the R&E(Research and Education) program have difficulties in making selection of topics, so they often progress their professor’s research as it is. I think that something is needed to stimulate students' intellectual curiosity, and azo dye could be a good topic for students. It has been widely used as a synthetic dye, and recently researches are being conducted in various fields such as a photosensor and a reducing agent. Therefore, we aimed to conduct experiments on photoisomerization and spectroscopic properties of azo dye and confirm this by DFT calculation.
The experiments of photoisomerization phenomenon of azobenzene, the experiments of color change of azo violet by pH, and the experiments of complex formation with azo violet and Mg2+ and the change of colors made the students have the intellectual curiosity of azo dye.
After that, theoretical DFT / TD-DFT calculation of azo dye was carried out. In this research, we confirmed the mechanism of the photoisomerization phenomenon of azobenzene based on the Potential Energy Surface (PES) of azobenzene we calculated. We also investigated the tautomerization mechanism of azo violet based on its PES. To understand the color change of azobenzene and azo violet due to substituents, the energy levels of HOMO and LUMO by substituents were calculated. We can see that the energy levels of HOMO and LUMO increase as the substituents are changed by NO2, CN, H, OH, NH2. It is confirmed that azo dye is in visible ray area by calculating the band gap. In order to know the complex formation and color change of azo violet and metal ions (M2+ = Mg, Ca, Mn, Fe, Zn), energy levels of HOMO and LUMO by metal ions were calculated. The calculation result showed that the energy levels of HOMO and LUMO increase as the period of the metal increases, and the energy levels of HOMO and LUMO increase mostly as the atomic number increases in the same period.
In this way, the color change of azo dye was confirmed by DFT / TD-DFT calculation. This research can be applied appropriately to school lessons or R&E program, adapted according to the level of students.
주제어
#R&E프로그램 DFT Azobenzene 광화학 Azoviolet
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