Visible Light [2 + 2] Cycloadditions for Reversible Polymer Ligation

Read the full paper here: Macromolecules (2018) DOI: 10.1021/acs.macromol.8b00613

We introduce visible light induced dynamic covalent chemistry as a powerful reversible ligation tool based on a wavelength-dependent photon efficiency analysis (WPEA). We demonstrate by a monochromatic wavelength scan of the reversible dimerization of styrylpyrene at constant photon count that the system is most effective in its forward reaction at 435 nm, while the highest reverse reaction efficiency is observed at 330 nm. Critically, these optimum wavelengths are not accessible by inspection of the UV/vis spectra of the monomer and the dimer. Application of the identified reaction conditions enabled an entirely λ-orthogonal photoreversible polymer ligation using visible light, including with readily available light sources. The current study thus makes a [2 + 2] reaction system applicable in the critical visible light regime based on quantitative wavelength resolved data for applications in recodeable surface design in biological environments as well as reprogrammable materials systems.