In the past two decades, π-conjugated organic compounds have attracted much attention due to their potential applications in various fields such as liquid crystals, light-emitting, and nonlinear optical materials and self assembling. Introduction of heteroaryl moieties into π-extended systems are particularly useful where electron transfer is necessary and is a way to modify and sometimes enhance properties of advanced "electro-optic". In π-conjugated materials, azaheterocycles such as pyrimidine, which owing to its aromaticity, its strong electron-withdrawing character, its high dipolar interaction and its pH sensibility, presents the requested characteristics to be incorporated in organic materials in view of numerous and various applications. Such molecular architectures and their applications are reported in this review.