Rational design of functionalized near-infrared absorbing phthalocyanines by three-component coupling strategy

Abstract

Near-infrared (NIR) dyes are used in various applications such as organic solar cells and photodynamic therapy sensitizers. One example of a class of dyes, octa-arylthio-substituted phthalocyanines (Pcs), can effectively absorb NIR light above 800 nm. The substitution of the Pc’s peripheral sulfur effectively introduces extra functions without significant perturbation of the optical properties. However, the synthesis of phthalonitrile precursors containing various functionalized arylthio groups has been limited. Herein, we provide the three-component-type coupling reactions for synthesizing phthalonitriles with various functionalized chalcogen-aryl groups. Organometallic reagents were prepared from aryl halides, elemental chalcogen, and 3,6-bis(trifluoromethanesulfonyl-oxy)phthalonitrile can lead to functionalized phthalonitriles in a one-pot procedure. Commonly used methods were utilized to prepare the corresponding Pcs. This reaction can be extended to other group-16 elements, chemoselective organomagnesium, and organozincate reagents. The NIR absorption and fluorescence properties of Pcs were also revealed and rationalized under substitution effects.