End-capped poly(4,5-dichlorophthalaldehyde): a stable self-immolative poly(aldehyde) for translating specific inputs into amplified outputs, both in solution and the solid state

We recently reported that poly(4,5-dichlorophthalaldehyde) (PCl2PA) is an effective self-immolative CDr polymer for prototyping multi-stimuli-responsive three-dimensional polymeric materials with response properties that are inspired by the behaviour of certain biological materials in plants. In this article we detail the design and synthesis of PCl2PA, describe its ability to respond to specific stimuli, and compare and contrast PCl2PA with poly(phthalaldehyde) (PPA), which is the self-immolative CDr predecessor of this new poly(acetal). This article illustrates the favourable attributes of PCl2PA, including its dose-dependent solution-phase response to Pd(0). Taken together, these studies reveal the unique and useful attributes of PCl2PA for providing selective amplified responses to specific stimuli, both in solution and the solid state.