Deuterated pyridine as the NMR solvent is expected to
affect tacticity splitting due to the ring current effect of the
aromatic ring [17], and also the electronic effect of the N
lone pair [18]. Detailed PLA spectra of 1H methyl and 13C
methine in CDCl3 and C5D5N are given in Fig. 2. Improved
shift separation is clearly observed for the 1H methyl region
in C5D5N (Fig. 2b), when compared with 1H methyl peaks in
CDCl3 (Fig. 2a). The well-resolved 1H methyl spectral region
in C5D5N can be used to get the tetrad information on the
methyl protons.