In the present letter we investigate the noncovalent interactions in the mixed coaggregates of 1,3,5-triphenyl-2-pyrazoline (TPP) and 1,4-dicyanonaphthalene (DCN) and their influence on the excited-state properties of the TPP-DCN. The theoretical results show that the pi-pi stacking interactions play an important role in the noncovalent interactions of the TPP-DCN coaggregates. The effect of the pi-pi interactions on the excited-state properties of the TPP-DCN is also fully investigated, and the results indicate that the TPP and DCN do not form an intermolecular charge-transfer complex in the ground state, whereas they form an exciplex in the excited state. (C) 2012 Elsevier B. V. All rights reserved.