Photodynamic bonds are stable in
the dark and can reversibly dissociate/form
under light irradiation. Photodynamic bonds are promising building
blocks for responsive or healable materials, photoactivated drugs,
nanocarriers, extracellular matrices, etc. However, reactive intermediates
from photodynamic bonds usually lead to side reactions, which limit
the use of photodynamic bonds. Here, we report that the Ru–Se
coordination bond is a new photodynamic bond that reversibly dissociates
under mild visible-light-irradiation conditions. We observed that
Ru–Se bonds form via the coordination of a selenoether ligand
with [Ru(tpy)(biq)(H2O)]Cl2 (tpy = 2,2′:6′,2″-terpyridine,
biq = 2,2′-biquinoline) in the dark, while the Ru–Se
bond reversibly dissociates under visible-light irradiation. No side
reaction is detected in the formation and dissociation of Ru–Se
bonds. To demonstrate that the Ru–Se bond is applicable to
different operating environments, we prepared photoresponsive amphiphiles,
surfaces, and polymer gels using Ru–Se bonds. The amphiphiles
with Ru–Se bonds showed reversible morphological transitions
between spherical micelles and bowl-shaped assemblies for dark/light
irradiation cycles. The surfaces modified with Ru–Se-bond-containing
compounds showed photoswitchable wettability. Polymer gels with Ru–Se
cross-links underwent photoinduced reversible sol–gel transitions,
which can be used for reshaping and healing. Our work demonstrates
that the Ru–Se bond is a new type of dynamic bond, which can
be used for constructing responsive, reprocessable, switchable, and
healable materials that work in a variety of environments.