A phthalocyanine–mestranol conjugate for photodynamic therapy prepared via click chemistry

Introduction of an azide group onto the periphery of a photodynamically effective phthalocyanine (Pc) derivative gives a useful building block for the preparation of Pc conjugates via Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (‘click chemistry’). In this way, Pc–mestranol and Pc–hept-1-yne conjugates (for comparison purposes) are synthesized and their absorption, photochemical, and photophysical properties are studied. The conjugate retains the advantageous photophysical and photochemical properties of Pc. Conjugation with mestranol may lead to improved localization in tumors whereas the Pc unit is responsible for the photodynamic effect.