Phthalocyanines and related compounds: organic targets for nonlinear optical applications

Phthalocyanines (Pcs) and related compounds with their extended two-dimensional pi-electronic delocalization are important targets to study nonlinear optical responses. The tailorability of these macrocycles allows the fine-tuning of the chemical structure and nonlinear optical response. In this article, the design and main properties of phthalocyanines for second- and third-order nonlinear optical (NLO) and optical limiting applications are discussed, both at the microscopic and macroscopic level. The points of view of synthetic organic chemists and physicists are accorded, the main aim of the review being to highlight the key problems of the held and place them within the general context of NLO materials.