CALCIUM COMPLEXES OF CARBOXYLATE-CONTAINING POLYAMIDE WITH STERICALLYDISPOSED NH-CENTER-DOT-CENTER-DOT-CENTER-DOT-O HYDROGEN-BOND - DETECTION OF THE POLYAMIDE IN CALCIUM-CARBONATE BY 13C CROSS-POLARIZATION MAGIC ANGLE SPINNING SPECTER/

Carboxylate-containing polyamides were synthesized from 2,6-di(amino)b enzoic acid and dimethylmalonyl dichloride, isophthaloyl dichloride, a nd fumaryl dichloride. These polymers, {NHC6H3(COO)NHCOC(CH3)(2)CO}(n) , {NHC6H3(COO)NHCO-m-C6H4CO}(n), and {NHC6H3(COO)NHCO-trans-CH= CHCO}( n), have seven to eight carboxylate units in a polymer chain, and thei r Ca(II) complexes possess NH ... O hydrogen bonds, which prevents the Ca-O dissociation by hydrolysis. CaCO3 was obtained from aqueous Ca2 and CO32- in the presence of the polyamide or the Na salt of these po lyamides ([Ca2+]/ [monomer unit] = 100) to give calcite, vaterite, and /or their mixture. We were able to observe polymers in CaCO3 utilizing the C-13 cross-polarization/magic angle spinning solid-state NMR. The binding of Ca(II) by carboxylate appears to be an important factor in these studies and may be relevant to biomineralization of CaCO3.