# Dynamically assembled photochromic cages operational in water with visible light

## TL;DR

Researchers created light-responsive nanostructures that can adapt to external stimuli, showing potential for use in biological systems.

## Contribution

The study introduces dynamic covalent cages that respond to visible light and other stimuli, revealing design principles for adaptable molecular machines.

## Key findings

- Dynamic covalent cages undergo reversible constitutional changes driven by visible light and external stimuli.
- Stable covalent cages can be isolated after reduction of dynamic imine bonds.
- The cages respond to red light in aqueous media, suggesting potential in vivo applications.

## Abstract

Producing chemical nanostructures that can mimic the efficient adaptability of complicated biological systems to environment changes is among the main goals of nanotechnology. Progress in this area requires understanding of the adaptation mechanisms towards external stimuli at the molecular level. Due to rapid and precise spatiotemporal addressability, light-driven dynamic systems are particularly attractive for such mechanistic studies. Here, we show efficient formation of dynamic covalent cages that undergo a series of reversible constitutional changes driven by visible light. Their complex, yet predictable and often quantitative response to irradiation and other external stimuli (metal ions, pH) reveals design principles that can be applied to assemble adaptable molecular machines showing life-like behavior. Upon reduction of the dynamic imine bonds, stable covalent cages are isolated. Their response to red light, also in aqueous media, indicates the potential for in vivo applicability, as red light can deeply penetrate human tissues.

Understanding adaptation mechanisms towards external stimuli at the molecular level is crucial for progress in the design of chemical nanostructures with diverse functions and increasing complexity. Here, the authors demonstrate efficient formation of dynamic covalent cages that undergo a series of constitutional changes driven by light and external stimuli.