Quantum-mechanical calculations of the intensity distribution in spectra of adenine tautomers: I. Spectra of resonant hyper-Raman scattering

Abstract

The spectra of resonant hyper Raman scattering of five tautomeric forms of adenine have been theoretically determined for the first time based on quantum mechanical calculations in the Herzberg-Teller approximation. The occurrence of three structures, Ade N 9 ,N 1 H + , Ade N 9 H(am), and Ade N 7 H(am), in an aqueous solution of adenine has been established.

Theoretical Investigation on the Substituent Effect of Halogen Atoms at the C8 Position of Adenine: Relative Stability, Vibrational Frequencies, and Raman Spectra of Tautomers

“…Different spectroscopic techniques, containing microwave spectroscopy, matrix-isolated spectroscopy, double resonance spectroscopy, IR spectroscopy, NMR spectroscopy, and photoelectron spectroscopy, have been used to investigate adenine and its derivatives in the isolated molecule state, the solid state, and aqueous solution. But the key problem is how to build the relation between tautomerization and vibrational spectra in experimental and theoretical studies. − A few of theoretical studies have been reported on halogen substituted at the C 8 position of adenine, but these studies mainly focused on changes of tautomerism, electronic structures, protonation and deprotonation, as well as the influence of the substituent effect on the hydrogen bonding interaction. Ladik and Bcizó studied the charge distribution of series of substituted adenine at the SCF MO level for understanding the nucleotide base antimetabolite-type possible anticarcinogenic activity in 1970 .…”