Structurally Diverse Manganese(II)–Diclofenac Complexes Showing Enhanced Antioxidant Activity and Affinity to Serum Albumins in Comparison to Sodium Diclofenac

The interactions of Mn II ions with the nonsteroidal anti‐inflammatory drug sodium diclofenac in the presence of 1,10‐phenanthroline and 2,2′‐dipyridylamine lead to the formation of the trinuclear [Mn 3 (diclofenac) 6 (1,10‐phenanthroline) 2 (MeOH)] ( 1 ) and the mononuclear [Mn(diclofenac) 2 (2,2′‐dipyridylamine)] ( 2 ), respectively, which have been characterized by X‐ray crystallography. Three different coordination modes of the diclofenac ligands exist in 1 , whereas the bidentate chelating mode is observed in 2 . In the initial evaluation of their biological properties and potential applications, the complexes exhibited good binding propensity to human or bovine serum albumin proteins and have relatively high binding constants. The ability of the compounds to scavenge 1,1‐diphenylpicrylhydrazyl, 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid), and hydroxyl radicals was evaluated, and 1 was the most‐effective scavenger among 1 , 2 , and sodium diclofenac.