Manganese 1,4,7-trimethyl-1,4,7-triazacyclononane complexes as driers for solvent-borne and high-solid alkyd resins

Abstract

This study reports the synthesis and catalytic properties of new mononuclear and dinuclear manganese(II) complexes bearing 1,4,7-trimethyl-1,4,7-triazacyclononane ligand (Me3TACN). They were prepared using a simple and scalable protocol starting from manganese(II) sulfonates and Me3TACN. Molecular structures of the manganese(II) complexes were determined by X-ray diffraction analysis on single crystals. The investigation of catalytic properties was directed toward the acceleration of the drying of alkyd resins. The manganese(II) complexes bearing Me3TACN ligand were found to be highly efficient primary driers, promoting oxygen uptake and crosslinking at the air-film interface, which governs the drying performance of alkyd coatings. The optimal concentration ranged between 0.003 wt.% and 0.006 wt.% of metal in dry matter content, which is considerably lower than recommended for commercial cobalt carboxylates. Alkyd coatings, cured by here reported manganese complexes show mechanical properties nearing those treated with commercial cobalt-based driers, which documents crucial role of the manganese complexes in controlling both surface drying and through-film curing dynamics and implies its commercial potential in the field of cobalt-free technologies for paint producing industry.