Potentiometric and viscosimetric titration of poly( N -acyldehydroalanines) containing asymmetric nucleic acid base derivatives as pendant groups

The potentiometric and viscosimetric titration curves of poly( N -acetyldehydroalanine) (PNAcDHA) were compared with those of the nucleic acid base-containing dehydroalanine backbone polymers poly{(+ −) and (−)− [2-(thymin-1-yl]{propanoamido}propenoic acid} (PTDHA and P(−)TDHA)). The behavior of PNAcDHA was similar to polyacids such as poly(acrylic acid), but PTDHA and P(−)TDHA displayed very strong nearest neighbor interactions, since the pH curves had an additional inflection at half neutralization that was sensitive to the ionic strength of the medium and the viscosity curves showed little expansion of the polymer coil with increasing ionization. NAcDHA–TDHA copolymers were prepared which showed similar behavior. These results suggested that PTDHA and P(−)TDHA were extended and conformationally restricted in aqueous solution compared to PNAcDHA, findings that agreed with the results of spectroscopic studies of these polymers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38811/1/080241110_ftp.pd