Rapid Access to Photoswitchable RNA Binders: Fluorination Enhances Protein Rescue by Exon Inclusion

Targeting RNA is a rich, yet largely untackled opportunity for controlling biological functions, with high potential for therapeutic intervention. However, it remains inherently challenging. Beyond RNA structural diversity, functional RNA motifs are frequently context‐dependent and transient, complicating the rational design of selective small‐molecule binders. We here develop novel photoswitchable ligands to target RNA. They offer highly desirable, precise intervention by enabling light‐controlled regulation of both direct RNA interactions and downstream events. Unfortunately, access to such photoswitchable RNA molecular tools is scarce, requiring complex and lengthy synthesis routes. We present a readily adaptable platform for the straightforward synthesis of photoswitchable RNA binders capable of targeting pre‐mRNA and restoring functional survival motor neuron (SMN) protein levels by rescuing exon inclusion. Evaluation of our compounds demonstrated that both fluorination and heteroaryl groups (e.g., benzo‐ and thioxozaole) enhance binding affinity to the targeted dsRNA with in‐cellulo activity. Importantly, molecular recognition and structure–activity relationships were rationalized through a combination of computational studies and NMR spectroscopy.