The photochemistry of V(V) tartrate clusters (V₄O₈tart₂) in water has been characterized, showing conversion to purple V(IV) species (V₂O₂tart₂). During this photochemical transformation, the reduction of the V(V) is accompanied by oxidation of the tartrate ligand, with some oxidative decarboxylation to form CO₂. This reaction can be reversible in air, if excess tartrate is around to re-form the tetrameric clusters. We have harnessed this photochemistry to create photoresponsive materials that feature V(V) coordination to polysaccharides. In these materials, the V(V) coordination leads to an increase in the stiffness of the materials, and changes the assembly of the polysaccharides as visualized with SEM. In addition, these materials show analogous photochemistry to the V(V) tartrate clusters, with a color change from yellow to blue/purple.

Top: V(V)-tartrate clusters (V<sub>4</sub>O<sub>8</sub>tart<sub>2</sub>) undergo a reversible (in air, XS ligand) photochemical transformation to V(IV) dimers (V<sub>2</sub>O<sub>2</sub>tart<sub>2</sub>). Bottom: This photochemistry also occurs in polysaccharide materials that feature V(V) coordination

Top: V(V)-tartrate clusters (V₄O₈tart₂) undergo a reversible (in air, XS ligand) photochemical transformation to V(IV) dimers (V₂O₂tart₂). Bottom: This photochemistry also occurs in polysaccharide materials that feature V(V) coordination

Carina Haddad

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