COMPLEXATION OF BORATE WITH POLY(1-(ACRYLAMIDO)-1-DEOXYLACTITOL) - DILUTE-SOLUTION VISCOSITY, B-11 NMR, AND C-13 NMR-STUDIES

The interaction of berate ions with poly(1-(acrylamido)-1-deoxylactito l) (PACL) in aqueous media was investigated. Dilute solution viscometr y revealed that low concentrations of Borax (Na2B4O7) increased the. i ntrinsic viscosity of PACL, while higher concentrations reduced it. B- 11 NMR spectra of berate complexes of methyl beta-D-galactopyranoside (M(beta)DGP) (taken to model the C-l' through C-6' portion of the PACL repeating unit) and the monomer 1-(aclylamido)-1-deoxylactitol (2) sh owed evidence for alpha,beta-bidentate, alpha,beta-dimer, and alpha,ga mma-bidentate berate complexes. The B-11 NMR spectrum of PACL-borate s howed alpha,beta-bidentate and alpha,beta-dimer only. The binding cons tants for the alpha,beta-bidentate and alpha,beta-dimer complexes were determined for M(beta)DGP and 2 by integration of the B-11 NMR signal s. C-13 NMR was used to identify the putative sites of complexation on PACL by comparing the spectra of berate complexes of M(beta)DGP and 2 with PACL-borate. Complexation was found to occur predominantly at th e C-6', C-4', and C-3' positions.