• pyridoacridines;
  • calliactine;
  • conformational analysis;
  • circular dichroism;
  • TDDFT calculations


The chiroptical properties of calliactine (2) have been studied experimentally as well as by quantum chemical calculations based on density functional theory (DFT). According to the DFT calculations, the four energetically lowest conformers of the title compound lie within a range of 1.1 kcal/mol and are separated from other conformers by an energy gap of nearly 9 kcal/mol. Based on their geometries, the excitation energies and rotational strengths have been calculated using time-dependent DFT (TDDFT) and the dipole velocity formalism. The circular dichroism (CD) spectrum of calliactine has been obtained as a Boltzmann-weighted superposition of the spectra of each of the four structures. By comparison of the calculated and experimental CD spectra, the absolute configuration of calliactine has been elucidated as S. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004