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The performance of antimicrobial polymers depends sensitively on the type of cationic species, charge density, and spatial arrangement of cations. Here we report antimicrobial polymers bearing unusually bulky tetraaminophosphonium groups as the source of highly delocalized cationic charge. The bulky cations drastically enhanced the biocidal activity of amphiphilic polymers, leading to remarkably potent activity in the submicromolar range. The cationic polynorbornenes with pendent tetraaminophosphonium groups killed over 98% E. coli at a concentration of 0.1 μg/mL and caused a 4-log reduction of E. coli within 2 h at a concentration of 2 μg/mL, showing very rapid and potent bactericidal activity. The polymers are also highly hemolytic at similar concentrations, indicating a biocidal activity profile. Polymers of a similar chemical structure but with more flexible backbones were made to examine the effects of the flexibility of polymer chains on their activity, which turned out to be marginal. We also explore variants with different spacer arm groups separating the cations from the backbone main chain. The antibacterial activity was comparably potent in all cases, but the polymers with shorter spacer arm groups showed more rapid bactericidal kinetics. Interestingly, pronounced counterion effects were observed. Tightly bound PF6– counteranions showed poor activity at high concentrations due to gross aggregate formation and precipitation from the assay media, whereas loosely bound Cl– counterions resulted in very potent activity that monotonically increased with increasing concentration. In this paper, we reveal that bulky phosphonium cations are associated with markedly enhanced biocidal activity, which provides an innovative strategy to develop more effective self-disinfecting materials. 

Herein, we demonstrate that homopolymerization and statistical copolymerization of 2-ethylhexyl thiophene-3-carboxylate and 2-ethylhexyl selenophene-3-carboxylate monomers is possible via Suzuki–Miyaura cross-coupling. A commercially available palladium catalyst ([1,3-bis(2,6-di-3-pentylphenyl)imidazol-2-ylidene](3-chloropyridyl)dichloropalladium( ii ) or PEPPSI-IPent) was employed to prepare regioregular conjugated polymers with high molecular weights (∼20–30 kg mol −1 ), and relatively narrow molecular weight distributions. The optical bandgap in the copolymer series could be reduced by increasing the concentration of selenophene-3-carboxylate in the material. Configurational triads were observed in the 1 H NMR spectra of the statistical copolymers, which were assigned using a combination of 2D NMR techniques. The use of a 1 H– 77 Se HSQC spectrum to further examine sequence distribution in the statistical copolymers revealed how 77 Se NMR can be used as a tool to examine the microstructure of Se-containing conjugated polymers.