Rhodanine-based Knoevenagel reaction and ring-opening polymerization for efficiently constructing multicyclic polymers

Abstract

Cyclic polymers have a number of unique physical properties compared with those of their linear counterparts. However, the methods for the synthesis of cyclic polymers are very limited, and some multicyclic polymers are still not accessible now. Here, we found that the five˗membered cyclic structure and electron withdrawing groups make methylene in rhodanine highly active to aldehyde via highly efficient Knoevenagel reaction. Also, rhodanine can act as an initiator for anionic ring-opening polymerization of thiirane to produce cyclic polythioethers. Therefore, rhodanine can serve as both an initiator for ring-opening polymerization and a monomer in Knoevenagel polymerization. Via rhodanine-based Knoevenagel reaction, we can easily incorporate rhodanine moieties in the backbone, side chain, branched chain, etc, and correspondingly could produce cyclic structures in the backbone, side chain, branched chain, etc, via rhodanine˗based anionic ring-opening polymerization. This rhodanine chemistry would provide easy access to a wide variety of complex multicyclic polymers.

Plasmonic Heating-Promoted Photothermal Synthesis of α-Cyanoacrylonitriles Over Au/h-BN Catalysts

“…On the basis of the above results and previous literature ( Motokura et al, 2008 ; Zhang et al, 2016 ; Lei et al, 2018 ; Cao et al, 2019 ; Zhang et al, 2020 ), a plausible mechanism based on a weak base-catalyzed cycle for this reaction is proposed in Figure 5 , applying the -NH 2 groups as catalytic sites and light-induced heat as the driving force. Firstly, an -NH 2 group of the catalyst abstracted a proton from malononitrile A to generate a carbanion B .…”

Cyclic topology enhances the killing activity of polycations against planktonic and biofilm bacteria

“…S1 and S2 (ESI†). The cyclic polymers C-P(PEMT) n were synthesized by rhodanine-initiated anionic ring-opening polymerization as reported before 50 and linear polymers L-P(PEMT) n were synthesized through BDMAT- initiated ring-opening polymerization. After the reaction, the 1 H NMR spectra of the resulting solution were recorded to characterize the monomer conversion rate.…”

“…26 Our group has developed an easy access to cyclic polymers through rhodanine-initiated anionic ring-opening polymerization. 50 Using this method, here, cyclic polycations poly(2-((allyloxy)methyl)thiirane-diethylamino) (C-P(PEMT-DEA) n ) and their linear analogues (L-P(PEMT-DEA) n ) have been synthesized and functionalized with tertiary amine (Fig. 1A).…”

Cyclic polymers: synthesis, characteristics, and emerging applications

“…68 Recently, a number of complex multicyclic polythioethers with cyclic units in the linear backbone and hyperbranched chain, as well as brush polymers with cyclic side chains, have been produced by combining rhodanine-based Knoevenagel reaction and anionic ring-opening polymerization. 69 These synthetic developments provide exciting opportunities to study the structure-property relationships of macromolecules, leading to better understanding on the biological properties of topologically unique biomolecules and new concepts in designing novel polymeric materials.…”