Electron Delocalization in Organic Materials

This lecture covers the supramolecular organization and electron delocalization in the solid state, including the origin of π-interactions, electron density distribution in molecules with π-conjugated systems, and the multipole expansion describing the electrostatic potential. It also discusses the electron-rich and electron-poor π-conjugated systems, resonance structures, and the influence of substituents on electron density distribution. Furthermore, it explores the intermolecular forces between π-conjugated molecules, packing patterns for electron-rich and electron-poor systems, and mixed systems. The lecture concludes with the learning outcome that polycyclic π-conjugated systems have a quadrupolar moment, and the importance of supramolecular packing in balancing intermolecular forces. The typical motifs of parallel-displaced π-stacking and edge-to-face orientation are highlighted as ideal packing arrangements in the solid state.