A Theoretical Investigation of the Structural, Spectroscopic and Optical Properties of Adenine

M. Alauddin, M. M. Islam, M. K. Hasan, T. Bredow, M. A. Aziz

Abstract


The structural, spectroscopic (IR, NMR and UV-Vis) and optical properties of adenine (6-aminopurine, C5H5N5) are investigated theoretically using HF/DFT hybrid approach B3LYP. The calculated results are compared with available experimental data. The optimized bond distances and bond angles are converged within ±0.01 Å and ±0.8° with respect to the experimental values. The investigation of 1H NMR chemical shift spectra of the aromatic C-H protons shows that the maximum deviation of the calculated chemical shift is ~ 0.53 ppm compared to the experimental data. The calculated vibrational spectra analysis shows four distinct IR active mode of vibrations which are assigned as scissoring vibration of –NH2, symmetric stretching vibration of –NH2, free –NH vibration and anti-symmetric stretching vibration of –NH2, respectively. The electronic and optical properties are calculated by Time Dependent Density Functional Theory (TD-DFT) approach. A reasonable agreement is obtained for the calculated optical absorption energy with the experimental value.


Keywords


TD-DFT, IR, NMR, Electronic properties, Optical absorption

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Dhaka University Journal of Science ISSN 1022-2502 (Print) 2408-8528 (Online)