The merit function for electrooptic applications of dipyrromethene-BF2 complexes were optimized using the electron density derivatives respect to an applied electric field. These derivatives were evaluated using ab initio quantum mechanical methods and as a result we present new complexes with second-order nonlinear optical properties and ground state dipole moment two times higher than the reference molecule (disperse red 1). The electron density derivatives were also used to explain the origin of the high values of both, the dipole moment and first hyperpolarizability, for the studied compounds. The study is completed with the evaluation of the vibrational contribution to the hyperpolarizability at infinity frequency. (C) 2003 Elsevier B.V. All rights reserved.