Titolo della tesi: Preparation of new chiral ligands immobilized on nanomaterials for applications in asymmetric catalysis
In my PhD research, focused on the preparation of new nanostructured catalysts for applications in asymmetric catalysis, I verified firstly the efficiency of a chiral amino alcohol ligand, previously developed by the research group, in different asymmetric reactions. Despite the numerous attempts, the ligand did not show any catalytic activity for the conjugate addition of dimethylmalonate to electron poor olefines. In the asymmetric transfer hydrogenation (ATH) it was necessary to replace the amino residue, and the introduction of benzylamine in the structure finally led to good results in the ATH of acetophenone (91 %, ee 65 %). Tests with differently functionalized phenones are underway.
At the same time, I dealt with the development of a new 1,2-diamine ligand potentially anchorable on nanoparticles. I tried to optimize the ligand structure varying the substituents on the two amino groups and testing the ligands in the Henry reaction. The disappointing results obtained require additional structure fine-tuning, which is still in progress.
I investigated the immobilization of ephedrine on magnetite nanoparticles, but the results in heterogeneous phase, still unsatisfactory, need to further investigation.
On the contrary, the immobilization of the chiral amino alcohol previously cited on magnetite nanoparticles and on silver-thiolate nanoclusters led to two easily recoverable nanostructured catalysts that showed in the Henry reaction a catalytic efficiency totally comparable to that in homogeneous phase. Further tests are still going on