Molecular Structures of Dipeptide–Palladium(II) Conjugated Complexes

The chiral tridentate 2,6‐pyridinedicarboxamide ligand L 1 H 2 bearing two dipeptide chains (‐ L ‐Ala‐ L ‐Pro‐NHBu) was designed. Complexation of L 1 H 2 with Pd(OAc) 2 was demonstrated to afford the dipeptide–palladium(II) conjugated complex [(L 1 )Pd(MeCN)] ( 1 ) with an ancillary acetonitrile ligand. In the crystal packing of 1 , a right‐handed helical‐like molecular arrangement was observed, wherein each assembly is connected through continuous intermolecular hydrogen bonds together with water molecules. The dipeptide–palladium(II) conjugated complex 1 was studied as a metalloreceptor through metal coordination to accommodate a guest ligand, 4‐aminopyridine, resulting in the formation of the dipeptide–palladium(II) conjugated complex [(L 1 )Pd(4APy)] ( 2 ). Each preorganized helical molecule of 2 is packed in a right‐handed helical‐like molecular arrangement in the crystal packing. The dipeptide–palladium(II) conjugated complex 2 was found to exhibit emission with a maximum at 652 nm in the solid state.