Structural characterization of poly( l-aspartate) with fluorinated benzyl side chains in the solid state as studied by high resolution 13C NMR spectroscopy

Abstract

Solid-state high-resolution 13C NMR spectra of poly( l-aspartate) with mono-, di- and per-fluorinated benzyl side chains in the solid state were measured as a function of temperature, in order to elucidate structural behavior of the main chain by substituting hydrogen atoms in phenyl rings with fluorine atoms. From the experimental results, it was found that poly( l-aspartate)s with mono-fluorinated benzyl side chains take the α R-helix form and those with di- and per-fluorinated benzyl side chains take the ω-helix and β-sheet forms at room temperature, respectively. Further, structural behavior of the fluorinated poly( l-aspartate)s was elucidated by elevating the temperature.