Chromism of Poly[1-trimethylsilyl)-1-propyne]

Poly[1-(trimethylsilyl)-1-propyne], PTMSP, both in solution and in the solid state, was found to exhibit color changes upon interacting with certain electron acceptors including trifluoroacetic acid and antimony pentachloride. The chemical structure of the polymer backbone is scarcely affected as indicated by NMR spectroscopic measurements. We suggest that the color changes result from the formation of charge-transfer complexes, possibly coupled with conformational rearrangements of chain segments from a twisted helical geometry to a more planar, conjugated structure.