Abstract
•Theoretical study on geometrical parameters and vibrational frequencies of neutral 2-quinolinol.•DFT and CCSD(T)-F12 energetics on lactam–lactim tautomarization and the cis–trans isomerization of the lactim.•The lactam form is confirmed to be the most stable isomer of 2-quinolinol.•Multiconfigurational calculations on electronic excitation of the S1←S0 transition.
We treat theoretically 2-quinolinol(lactam), an analog of carbostyril and DNA bases. We characterized the ground state structure of 2-quinolinol and its isomer(lactim) using density functional theory(DFT). The reaction profile and energetics for lactam–lactim tautomerization and cis-lactim to trans-lactim isomerization predicted with explicitly correlated methods. We explored the pattern of the lowest singlet and triplet manifolds of states and electronic S1←S0 transitions using multiconfigurational methodologies. The theoretical results are compared with available experimental data and used to interpret the on-going photoelectron study of 2-quinolinol. Our analysis should help to understand the effect of tautomerism and aromaticity on the DNA bases.