Novel ligands from direct benzylic functionalisation of tris(2-pyridylmethyl)amine

Tris-(2-pyridylmethyl)amines (TPA or TPMA) are polipyrydine-based ligands extensively used in catalysis and supramolecular chemistry due their capability to form stable tetradentate complexes with a large variety of metals. The unsubstituted ligand, which is also commercially available, can be synthesised by consecutive alkylation of a picoline or by reductive amination of a pyridine aldehyde. In this article, we report a novel synthetic method which opens to the post-functionalisation of these ligands in the benzylic position. This novel derivatization strategy, beside providing synthetic access to novel structures and functions, has been used to prepare a series of metal complexes which have been tested in photochemical hydrogen evolution.