Green light LED activated ligation of a scalable, versatile chalcone chromophore

Abstract

Herein we introduce a photoreactive chalcone moiety that can be synthesized at a scale of several grams with ease, and efficiently undergoes a [2 + 2] photocycloaddition with light up to just below 500 nm as determined by an action plot. The peak chalcone reactivity is at 440 nm which is red-shifted by 25 nm compared to the absorption maximum at 415 nm. The chalcone was attached to a RAFT agent enabling reversible deactivation radical polymerization. The resulting polymer subsequently took part in a photoligation triggered by light from an LED centered at 505 nm. Thus, we introduce a chalcone that is capable of overcoming the synthetic disadvantages associated with styrylpyrenes and can readily undergo [2 + 2] photocycloadditon with visibile light.