Electrochemistry and electrogenerated chemiluminescence of all-trans conjugated polymer poly[distyrylbenzene-b-(ethylene oxide)]s

The electrochemistry and electrogenerated chemiluminescence (ECL) of two linear, stereoregular, and structurally defined PPV derivatives, poly[distyrylbenzene-b-(ethylene oxide)]s, with respective 12 and 16 of ethylene oxide repeat units in the backbone, abbreviated as DE-1 and DE-2, have been studied on glassy carbon and Pt electrodes in CH2Cl2 and CH3CN containing 0.10 M tetra-n-butylammonium perchlorate (TBAP). In CH2Cl2, a one-electron transfer, reversible oxidation at approximately 0.75 V vs Ag/Ag+ (10 mM AgNO3 in CH3CN) was observed for both polymers. Porous polymer films were electrochemically formed on the electrode with multiple cyclic potential scanning. Cast films of DE-1 and DE-2 on the electrode prepared from 1.0 mM of the corresponding CH2Cl2 solutions were used for studies in CH3CN containing 0.10 M TBAP due to their limited solubility in the solvent. A film-type of oxidation was found at approximately 0.80 V vs Ag/Ag+ in CH3CN when a scan rate of less than 1 V/s was used. The soluble oxidation product can be captured and reduced and then reoxidized in solution-phase at the electrode at a relatively high scan rate of, e.g., 2 V/s. ECL responses with a maximum emission at approximately 1.10 V vs Ag/Ag+ were obtained with the cast films in CH3CN (0.10 M TBAP) in the presence of 43 mM tri-n-propylamine (TPrA) after both TPrA and film were oxidized. The ECL is believed to be resulted from the interaction between the oxidized polymer species and the strong reducing TPrA free radical (TPrA*) generated after the deprotonation of TPrA*+ cation species.