3,6-Bis-(2-pyridyl)-pyridazine as supramolecular (co)initiator for DL-lactide polymerization

The synthesis of a new hydroxy functionalized dipyridylpyridazine by a Diels-Alder reaction between 5-hexyn-1-ol and dipyridyltetrazine was reported. An aluminum alkoxide was generated in situ from this functional ligand to initiate the controlled ring opening polymn. of of DL-lactide resulting in a macroligand with a mol. wt. of 3,900 Dalton. 1H-NMR spectroscopy revealed that indeed the ligand was incorporated in the polymer. The stepwise addn. of tetrakis(acetonitrile)copper(I) hexafluorophosphate to the macroligand was investigated with UV-Vis spectroscopy. Upon addn. of tetrakis(acetonitrile)copper(I) hexafluorophosphate an absorption band at 440 nm appeared and maximal absorption was obtained after addn. of 1 equiv copper(I). Both the absorption max. and the full complexation at 1 equiv of Cu(I) are typical for these grid-like complexes. [on SciFinder (R)]