Abstract
We report the use of electrogenerated anthraquinone radical anion (AQ•−) to trigger fast catalytic depolymerization of polymers derived from poly(dithiothreitol) (pDTT)—a self-immolative polymer (SIP) with a backbone of dithiothreitols connected with disulfide bonds and end-capped via disulfide bonds to pyridyl groups. The pDTT derivatives studied include polymers with simple thiohexyl end-caps or modified with AQ or methyl groups by Steglich esterification. All polymers were shown to be depolymerized using catalytic amounts of electrons delivered by AQ•−. For pDTT, as little as 0.2 electrons per polymer chain was needed to achieve complete depolymerization. We hypothesize that the reaction proceeds with AQ•− as an electron carrier (either molecularly or as a pendant group), which transfers an electron to a disulfide bond in the polymer in a dissociative manner, generating a thiyl radical and a thiolate. The rapid and catalytic depolymerization is driven by thiyl radicals attacking other disulfide bonds internally or between pDTT chains in a chain reaction. Electrochemical triggering works as a general method for initiating depolymerization of pDTT derivatives and may likely also be used for depolymerization of other disulfide polymers.
Funder
Independent Research Funder Denmark
Subject
Chemistry (miscellaneous),Analytical Chemistry,Organic Chemistry,Physical and Theoretical Chemistry,Molecular Medicine,Drug Discovery,Pharmaceutical Science