Parallel design strategy and rational study of crystal engineering of novel 3,4-ethylenedioxythiophene derivatives for solid state polymerization†
Several 3,4-ethylenedioxythiophene (EDOT) derivatives containing different heteroatom linkers were rationally designed along parallel directions. They were synthesized and studied as potential candidates for solid state polymerization (SSP). The detailed characterization of these corresponding polymers was carried out using UV-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and several key crystal structures were analyzed. Our study reveals that heteroatoms like C, Si and P are good linkers between EDOT units, and most monomers can be spontaneously polymerized successfully by annealing at a moderate temperature. Due to the flexible short single heteroatom linkers, these monomers may rotate freely under heating, to meet the requirement for the success of SSP. By carefully analyzing typical crystal structures, direct evidence for the success of SSP was obtained for better understanding of the SSP process. In addition, effective Hal/Hal distance was defined and a new SSP model was proposed.