Synthesis and Characterization of Linear Cerium(IV) Schiff-Base Coordination Polymers

Abstract

The first soluble linear Schiff-base rare earth coordination polymer, catena-poly[cerium-(4)-[mu]-N,N[prime],N[double prime],N[prime][double prime]-tetrasalicylidene (3,3[prime]-diaminobenzidinato)-O,N,N[prime],O[prime],O[double prime],N[double prime],N[prime][double prime],O[prime][double prime]] [Ce(tsdb)]n, has been synthesized. The mathematical reaction between tetrakis(acetylacetonato) cerium(IV), [Ce(acac)[sub 4]], and the premade tetrasalicylidene-3,3[prime]-diaminobenzidine Schiff base, [H[sub 4]tsdb], and the condensation reaction between the new chelate tetrakis(salicylaldehydato)cerium(IV), [Ce(sal)[sub 4]], and 3,3[prime]-diaminobenzidine were confirmed to be effective syntheses for the preparation of coordination polymers with stoichiometrically controlled polymerization. The polymers have been characterized by gel permeation (size exclusion) chromatography, viscosity measurements, and [sup 1]H nuclear magnetic resonance end-group analyses. On the basis of the results from the end-group analysis, polymers with number-average molecular masses ([bar M][sub n]) as high as 30,000 have been obtained. The polymers exhibit high thermal stability and high glass-transition temperatures. Mark-Houwink constants of a = 0.76 and K = 7.36 [times] 10[sup [minus]5] have been obtained from the intrinsic viscosities (in dL/g) and the NMR [bar M][sub n] values.