Amino acid complexes with tin as a new class of catalysts with high reactivity and low toxicity towards biocompatible aliphatic polyesters

Abstract

A series of complexes consisting of natural amino acids and tin (Sn(AA)2) prepared by conventional neutralization reactions were tested as a new class of cost-effective catalysts with high reactivity and low toxicity towards some biocompatible aliphatic polyesters. In our system, by using a simple catalyst and a benzyl alcohol (BnOH) initiator, biocompatible, and biodegradable aliphatic polyesters, such as poly(l-lactide), poly(e-caprolactone), and poly(trimethylene carbonate), were well prepared. The results demonstrated that Sn(AA)2 catalysts, especially the phenylalanine-tin complex (Sn(L-Phe)2) (Mn, up to 194 kg/mol), were suitable for the synthesis of moderate and high-molecular weight poly(l-lactide), which exhibited good biocompatibility. Analysis of the backbone structure and end groups of low-molar-mass polymers by using MALDI-TOF mass spectra and 1H NMR spectroscopy suggested that the reaction proceeds by a dual activation mechanism. Given their low cost, simple preparation, high reactivity, and low toxicity, complexes consisting of natural amino acids and tin are promising for industrial-scale production of biocompatible aliphatic polyesters. A series of complexes consisting of natural amino acids and tin were developed as a new class of cost-effective catalysts with high reactivity and low toxicity towards some biocompatible aliphatic polyesters. The results demonstrated that Sn(AA)2 catalysts, especially the phenylalanine-tin complex (Sn(L-Phe)2) (Mn, up to 194 kg/mol), were suitable for the synthesis of moderate- and high-molecular-weight poly(L-lactide), which exhibited good biocompatibility.