Novel optically active helical poly(N-propargylthiourea)s: synthesis, characterization and complexing ability toward Fe(iii) ions

Abstract

An enantiomeric pair of novel chiral N-propargylthiourea monomers (monomers 1 and 2) and their racemate (monomer 3) were synthesized and polymerized in the presence of (nbd)Rh⁺B⁻(C₆H₅)₄ as a catalyst. The resulting poly(1) and poly(2) could adopt stable helices and demonstrate optical activity in solvents of low polarity (e.g.CHCl₃), according to circular dichroism and optical rotation measurements. But for poly(3), no considerable CD signal was observed at 320 nm and above. Poly(1) and poly(2) kept stable helical structures in a temperature range from 0–60 °C, while failed to maintain helix in polar solvents. Helical poly(1) and poly(2) exhibited strong complexing ability towards Fe(III) ions, based on which novel sensors may be developed next.