Chemical behavior of optically active poly[thio 1-(N,N-disubstituted aminomethyl) ethylenes] in CuCl2-methanol mixtures: Induced optical activity of bound Cu(II)

(+)-Poly[thio 1-(N-sec-butyl-N-methylaminomethyl) ethylene] (I) and (-)-poly[thio 1-(N-methyl-N-(1-phenylethyl)aminomethyl) ethylene] (II) are soluble in methanol or in a 10/90 dioxane-methanol mixture in the presence of CuCl₂. This salting-in effect results from interactions between macromolecules and this salt. With a large excess of salt (molar ratio > 8) a precipitate is obtained whose composition is close to a CuCl₂:monomer unit ratio of unity. Ultraviolet, optical rotatory dispersion (ORD) and circular dichroism (CD) spectra in solution are described. The three extrinsic Cotton effects observed between 300 and 800 nm are assigned to charge transfer and d-d electronic transitions of Cu(II) complexed with the macromolecules. In the same solvent system, Cu(II) shows similar induced optical activity in the presence of a nonaminated homolog, (+)-poly(propylene sulfide) taken as a model of the chains of I and II. No extrinsic Cotton effects are observed in the presence of an optically active tertiary amine without the thioether sulfur atom, (+)-N-sec-butyl-N-methyl-N-(oxirane-2-ylmethyl)amine. It is concluded that Cu(II) gives rise to charge-transfer complexes with sulfur atoms, while tertiary amine groups are probably protonated in this particular medium.