End-group functionalization and postpolymerization modification of helical poly(isocyanide)s

This contribution presents the synthesis of helical alkyne-terminated polymers using a functionalized Nickel complex to initiate the polymerization of menthylphenyl isocyanides. The resulting polymers display low dispersities and controlled molecular weights. Copper-catalyzed azide/alkyne cycloadditions (CuAAC) are performed to attach various azide-containing compounds to the polymer termini. After azido-phosphonate moiety attachment the polymer displays a signal at 25.4 ppm in the ³¹P NMR spectrum demonstrating successful end-group functionalization. End-group functionalization of a fluorescent dye allows to determine the functionalization yield as 89% (±8). Successful ligation of an azide-functionalized peptide sequence (M_KLA = 1547 g/mol) increases the M_n from 5100 for the parent polymer to 6700 for the bioconjugate as visualized by GPC chromatography. Analysis by CD spectroscopy confirms that the helical conformation of the poly(isocyanide) block in the peptide–polymer conjugate is maintained after postpolymerization modification. These results demonstrate an easy, generalizable, and versatile strategy toward mono-telechelic helical polymers.