Rhodanine-Based Chromophores: Fast Access to Capable Photoswitches and Application in Light-Induced Apoptosis

Abstract

Molecular photoswitches are highly desirable in all chemistry-related areas of research. They provide effective outside control over geometric and electronic changes at the nanoscale using an easy to apply, waste-free stimulus. However, simple and effective access to such molecular tools is typically not granted, and elaborate syntheses and substitution schemes are needed in order to obtain efficient photoswitching properties. Here we present a series of rhodanine-based photoswitches that can be prepared in one simple synthetic step without requiring elaborate purification. Photoswitching is induced by UV and visible light in both switching directions, and thermal stabilities of the metastable states as well as quantum yields are very high. An additional benefit is the hydrogen-bonding capacity of the rhodanine fragment, which enables applications in supramolecular or medicinal chemistry. We further show that the known rhodanine-based inhibitor SMI-16a is a photoswitchable apoptosis inducer. The biological activity of SMI-16a can effectively be switched ON or OFF by reversible photoisomerization between the inactive E and the active Z isomer. Rhodanine-based photoswitches therefore represent an easy to access and highly valuable molecular toolbox for implementing light responsiveness to the breadth of functional molecular systems.

Dicyanorhodanine-Pyrrole Conjugates for Visible Light-Driven Quantitative Photoswitching in Solution and the Solid State

“…Dube and coworkers presented a survey of heterocyclic HTI-photoswitches that displayed notable photoswitching performances along with bistable isomers based on chalcogen and H-bonding interactions . The same group recently reported aryl- and heteroaryl-based (e.g., imidazole, indole) rhodanine chromophores as highly photoswitchable motifs …”

Ion-selective response of visible light photoswitchable indole-hemithioindigo: toward chemical sensing of fluoride and hydroxide

“…In ion-selective chemosensors, target ions are bound to specific molecular receptors with high affinity and selectivity, establishing an equilibrium with these receptors. 1–6 In contrast, chemodosimeters, operating in a non-equilibrium mode and utilizing reaction kinetics, offer another avenue for discriminating between different target analytes. 7–10 A myriad of chemodosimeters have been reported based on irreversible reactions with the target ions or catalyzed by them.…”