THE EFFECT OF COMBINATION OF OXYGEN AND NITROGEN FUNCTION GROUP ON CARBON DOTS ABSORBANCE SPECTRUM THROUGH TIME-DEPENDENT DENSITY FUNCTIONAL THEORY (TD-DFT) STUDY

• Main Author: Umami, Reza
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62559
• Institution: Institut Teknologi Bandung

Carbon dots (CDs) have attracted great scientific interest due to their remarkable characteristics, low cost, toxicity, and broad potential applications. The synthesis process of CDs through bottom-up methods such as hydrothermal, microwave heating and pyrolysis is a simple and inexpensive synthesis method suitable for application in large-scale production. However, the as-synthesized CDs through this method are usually decorated with various types of Oxygen and Nitrogen based functional groups. On the other hand, these functional groups are also expected to influence the optical and electronic properties of CDs. Therefore, in this study, the effect of various Nitrogen and Oxygen functional groups on the optical properties of CDs material was evaluated based on the Time Dependent-Density Functional Theory (TD-DFT) study. The Calculations were performed by gaussian09 using the functional correction B3LYP, and the basis set 6-311G**(d,p). Optimization of geometry, oscillator strength and energy transitions were calculated to study the UV-Vis absorbance in the NIR region of the CDs given Oxygen and Nitrogen functional groups. The calculation results show that the carbonyl functional group (C=O) is considered to be the most effective way to down-shifting the unoccupied molecular orbital energy, reducing the energy gaps of the CDs. Besides, the Nitrogen configurations could serve an excited electron via free electron-donor to the ? system of the main structure of CDs. This study indicate that the combination of Oxygen and Nitrogen functional groups can produce a new absorbance peak in the first NIR window region, thereby opening up new applications for CD as a photothermal agent in photothermal cancer therapy.