Application of C–H Functionalization in the Construction of Pyrene-Azobenzene Dyads

Abstract Herein we report synthesis of pyrene-azobenzene dyads using the Pd(II)-catalyzed directing-group-assisted arylation of the ortho C(sp2)–H bond of pyrenecarboxamides as a key transformation. Many examples of directly connected pyrene-azobenzene dyads (without any linker) and glycine-based azobenzene-pyrene dyads have been synthesized. Initial incorporation of an acetanilide unit in the pyrene skeleton through Pd(II)-catalyzed directing-group-assisted ortho C(sp2)–H arylation by using iodoacetanilide was followed by the transformation of the acetanilide into an azobenzene unit to give the pyrene-azobenzene dyad. UV-Vis spectroscopic studies were performed to get the absorption properties (λmax (nm)) of all the compounds. Preliminary photoswitching studies in both forward and reverse directions and their related thermal reverse Z→E isomerization kinetics measurements were ascertained for representative compounds. Considering the importance of pyrene and azobenzene linked motifs as important chromophore-based photoswitchable molecules in chemical, materials, and supramolecular sciences research fields, this work enriches the library of pyrene-azobenzene dyads.