Sulfonated Pyrene as a Photoregulator for Single‐Stranded DNA Looping

Controlling the conformation and function of biomolecules through photoregulators holds great promise as a spatiotemporally controllable tool for disease control. In addition, introducing photoregulators into biomolecules has also found applications in constructing smart nanomaterials. In spite of the astonishing advances that have been made in the past few years, realizing highly controllable and efficient regulation over the conformation and function of biomolecules under physiological conditions is still challenging. Herein, sulfonated pyrene SPy was synthesized and used as a photoregulator to control the looping of single‐stranded DNAs (ssDNAs) in aqueous solution. Due to its water solubility, SPy merits use in the study of biomolecules in aqueous solution. The looping of the doubly SPy ‐modified ssDNAs is stimulated by irradiation and regulated by SPy . Photoionization generates the radical cation of SPy ( SPy .+ ). The association of SPy . + with its neutral counterpart, SPy , gives rise to the dimer radical cation of SPy ( SPy 2 . + ). During the association process, the stabilization energy released to form SPy 2 . + provides a driving force for the looping of ssDNAs. Conversely, the formed loop conformations were trapped by the formation of SPy 2 . + , and this allowed the looping dynamics to be investigated. The results reported herein suggest potential of SPy as a photoregulator for controlling the conformation and function of biomolecules under physiological conditions.