Electrochemical and Optical Properties of D-A-A-A-D Azomethine Triad and Its NIR-Active Polymer

The azomethine <b>TPA-(BTZ)₃-TPA</b> with a donor-acceptor-acceptor-acceptor-donor structure has been synthesized and characterized. Azomethine <b>TPA-(BTZ)₃-TPA</b> exhibited luminescence properties and a positive solvatochromic effect. Electropolymerization on terminated triphenylamine groups was used to obtain a thin layer of the polyazomethine <b>poly-[TPA-(BTZ)₃-TPA]</b>. Further investigation of oxidation/reduction properties of <b>poly-[TPA-(BTZ)₃-TPA]</b> via cyclic voltammetry showed that the polymer undergoes two reversible oxidation/reduction processes due to the presence of tetraphenylbenzidine moieties. Electrochromic properties of the polyazomethine <b>poly-[TPA-(BTZ)₃-TPA]</b> were investigated via spectroelectrochemistry. It was observed that the polymer in its neutral state is orange, and the color changes to green upon electro-oxidation. The stability of the polymer during multiple oxidation/reduction cycles, response times, and coloration efficiency were also investigated.