Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34 M. Curie-Skłodowska Str., Zabrze 41-819, Poland.
Electroactive Polymers and Plasmochemistry Laboratory, "Petru Poni" Institute of Macromolecular Chemistry, Aleea Grigore Ghica Vodă nr. 41A, Iaşi 700487, Romania.
J Phys Chem B. 2021 Aug 5;125(30):8588-8600. doi: 10.1021/acs.jpcb.1c05390. Epub 2021 Jul 27.
Three polyazomethines and their corresponding model compounds were protonated with trifluoroacetic acid, and its effect on their optical (UV-vis absorption and photoluminescence) properties and electrochemical behavior has been studied, in the context of the presence and elongation of alkoxy side groups. Moreover, the effect of environment dielectric constants (i.e., polarity of the solvent) was considered on the doping process. It has been proven that the presence of alkoxy side groups is necessary for protonation to occur, while unsubstituted compounds undergo hydrolysis to constitutive units. Acid doping of imines consisting of alkoxy side chains has resulted in a distinct bathochromic shift (>200 nm) of the low-energy absorption band. Even the length of alkyl chains has not affected the position of shifted bands; it has been observed that azomethines with smaller, methoxy side groups undergo the protonation process much faster than their octyloxy-substituted analogues, due to the absence of steric hindrance. The electrochemical studies of these alkoxy-substituted imines have indicated a better p-type behavior after protonation induced by the capability of the protonated form to easily oxidize in acetonitrile and to generate the native molecules. The environmental polarity has also had impact on the doping process, which took place only in low-polar media.
三种聚亚甲胺及其相应的模型化合物被三氟乙酸质子化，研究了烷氧基侧基的存在和伸长对其光学（紫外可见吸收和光致发光）性质和电化学行为的影响。此外，还考虑了环境介电常数（即溶剂的极性）对掺杂过程的影响。事实证明，烷氧基侧基的存在对于质子化的发生是必要的，而未取代的化合物则发生水解生成组成单元。由烷氧基侧链组成的亚胺的酸掺杂导致低能量吸收带发生明显的红移（>200nm）。甚至烷基链的长度也没有影响位移带的位置；观察到具有较小甲氧基侧基的亚甲胺比其辛氧基取代的类似物更快地经历质子化过程，这是由于不存在空间位阻。这些烷氧基取代的亚胺的电化学研究表明，在乙腈中，质子化形式由于易于氧化而产生本征分子，从而表现出更好的 p 型行为。环境极性也对掺杂过程有影响，只有在低极性介质中才会发生掺杂。
