Abstract
Reaction of N-(2,4-dinitrophenyl)pyridinium chloride (salt(Cl−)) with sodium dicyanamide (Na(CN)2N) resulted in anion exchange between Cl− and (CN)2N− to yield a new Zincke salt, salt((CN)2N−). Reactions of salt((CN)2N−) with piperazine, specifically (R)-(−)- or (S)-(+)-2-methylpiperazine under eco-friendly conditions, such as in aqueous solution, in the absence of a catalyst, and at room temperature, resulted in pyridinium ring opening to yield ionic high-molecular-weight polymers with 5-2,4-dienylideneammonium dicyanamide units or chiral 5-(2-methylpiperazinium)-2,4-dienylideneammonium dicyanamide units, namely, polymer(H;(CN)2N−), polymer(R-Me;(CN)2N−), and polymer(S-Me;(CN)2N−). UV-Vis measurements revealed that the π-conjugation system expanded along the polymer chain due to the orbital interaction between the electrons on the two nitrogen atoms of the piperazinium ring. Circular dichroism (CD) measurements revealed a helical conformation of the main chain in polymer(R-Me;(CN)2N−) and polymer(S-Me;(CN)2N−). The reaction of polymer(H;(CN)2N−) with p-phenylenediamine (PDA) caused recyclization of the 2,4-dienylideneammonium unit and resulted in depolymerization to yield N-(4-aminophenyl)pyridinium dicyanamide. Cyclic voltammetry analysis suggested that the polymers obtained in this study undergo electrochemical oxidation and reduction.
Highlights
Introduction pConjugated polymer main chains generally consist of aromatic rings and unsaturated bonds that build an expanded p-conjugation system
Other polymers were synthesized in a similar manner
Synthesis Reaction of N-(2,4-dinitrophenyl)pyridinium chloride (salt(ClÀ)) with sodium dicyanamide resulted in anion exchange between ClÀ and (CN)2NÀ to yield N-(2,4-dinitrophenyl)pyridinium dicyanamide (salt((CN)2NÀ)) (Scheme 1)
Summary
Introduction pConjugated polymer main chains generally consist of aromatic rings and unsaturated bonds that build an expanded p-conjugation system. The reactions of salt((CN)2NÀ) with piperazine, R-(À)-2-methylpiperazine, S(+)-2-methylpiperazine and 2-methylpiperazine in water at room temperature led to ring-opening of the pyridinium ring to afford polymer(H;(CN)2NÀ), polymer(R-Me;(CN)2NÀ), polymer(SMe;(CN)2NÀ) and polymer(rac-Me;(CN)2NÀ), in 71%, 34%, 36% and 21% yields, respectively (Scheme 2).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
