SYNTHESIS AND CHARACTERIZATION OF THE THERMALLY STABLE COPOLYMER OF TETRAKIS(SALICYLALDEHYDATO-O,O')ZIRCONIUM(IV) AND 3,3'-DIAMINOBENZIDINE

A new soluble linear Schiff-base coordination polymer catena-poly[zirconium(IV)(μ-N,N′,N″,N‴-tetrasalicylidene-3,3′-di-aminobenzidinato-O,N,N′,O′:O″,N″,N‴,O‴)] has been synthesized via the condensation of 3,3′-diaminobenzidine with tetrakis(salicylaldehydato-O,O′)zirconium(IV) in dry dimethyl sulfoxide. The copolymer chain length has been evaluated by 1H NMR spectroscopy (end-group analysis), gel permeation (size exclusion) chromatography, and viscosity measurements. A copolymer average degree of polymerization of up to 92 has been obtained by careful stoichiometry control plus fractional precipitation. An electronic charge-transfer transition at about 400 nm has also been observed with a molar extinction coefficient of 3.2 × 104 L (mol of Zr)−1 cm−1. The polymer shows high thermal stability to about 770 K as measured by thermal gravimetric analysis and has a glass transition temperature of 347 K as measured by differential scanning calorimetry. The glass transition temperature of the analogous 1,2,4,5-tetraaminobenzene copolymer with tetrakis(salicylaldehydato)zirconium(IV) has also been determined to be 360 K. © 1990, American Chemical Society. All rights reserved.