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-FTCDI complexes and compared to experimental data, where available. (C) 2008 Elsevier B.V. All rights reserved.