Photoinduced intermolecular and intramolecular charge transfer in the mixed coaggregates of pyrazoline and dicyanonaphthalene

Photoinduced charge transfer (CT) and excited state properties in the mixed coaggregates of 1,3,5-triphenyl-2-pyrazoline (TPP) and 1,4-dicyanonaphthalene (DCN) are investigated theoretically, using time-dependent density functional theory (TD-DFT) as well as the two-dimensional (2D) site (transition density matrix) and three-dimensional (3D) cube (transition density and charge difference density) representations. The calculated results indicate that a strong absorption band stems from the S0 → S4 transition. There are electron–hole coherences between TPP and DCN monomers, which are shown by 2D site representation. Direct visual evidence revealed by 3D cube representations indicates that photoinduced CT mechanism for the mixed coaggregates of TPP and DCN is the mixture of intermolecular and intramolecular CT in the vertical absorption. Some phenyl group of TPP monomer not only serves as the electronic donor in the intramolecular CT, but also in the intermolecular CT process.