Inside Back Cover: Dinuclear Zinc–N‐Heterocyclic Carbene Complexes for Either the Controlled Ring‐Opening Polymerization of Lactide or the Controlled Degradation of Polylactide Under Mild Conditions (ChemCatChem 5/2014)

Multipurpose zinc carbene catalyst The cover picture features a dinuclear zinc–N-heterocyclic carbene (NHC) catalyst. In their Full Paper on p. 1357 ff., S. Dagorne, T. Avilés, M. J. Calhorda et al. report that such zinc–NHC alkoxide species polymerize lactide to produce well-defined polylactic acid and, remarkably, also mediate the controlled degradation (depolymerization) of polylactic acid under mild conditions to produce methyl lactate as the major reaction product. DFT studies of the polymerization reaction highlight the beneficial effect of two zinc centers in close proximity. The work shows that biocompatible zinc(II) complexes can mediate the polymerization of lactide and the controlled degradation of polylactic acid under mild conditions (room temperature).