Vibrational and electronic structure of PTCDI and melamine–PTCDI complexes

Vibrational FT-IR, FT-IR/ATR and Raman spectra of 3,4,9,10-perylene-tetracarboxylic diimide (PTCDI) and 1,3,5-triazine–2,4,6-triamine (melamine) molecules are assigned based on B3LYP/6-31G(d) quantum chemical calculations. Theoretical IR spectrum of melamine–3PTCDI complex is discussed in relation with the component molecules of the complex. Hydrogen bonding parameters and interaction energies for melamine–PTCDI complexes with one, two or three PTCDI molecules, as well as dimers formed from melamine and PTCDI molecules are calculated and different possibilities of auto-assembling observed by different groups are discussed in the light of present theoretical results. The energies and shapes of the frontier molecular orbitals and HOMO–LUMO gaps are calculated for neutral and ionic forms of PTCDI, for melamine and melamine–PTCDI complexes and compared to experimental data, where available.