Solid state photodimerisation of tetrathiafulvalene derivatives bearing carboxylate and carboxylic acid substituents

Structural and spectroscopic studies on the [2+2] photodimerisation of TTF derivatives show that solid state cycloaddition leads to a dimer with a face-to-face structure. The type of phototransformation of the material depends not only on the optical characteristics of the reactant but also on those of the product.