A family of one-dimensional lanthanide complexes bridged by two distinct carboxylate ligands with the Dy analogue displaying magnetic relaxation behaviour.

A series of isostructural lanthanide one-dimensional (1D) chain complexes, [Ln(INNO)(Bza)(HO)]·(HO) {INNO = isonicotinate N-oxide, Bza = benzoic acid; Nd(1), Eu(2), Gd(3), Tb(4), Dy(5), Er(6) and Y(7)}, have been successfully isolated by hydrothermal reactions utilizing two distinct carboxylates as co-ligands. Due to the similar steric hindrance of the two carboxylic ligands, the neighboring lanthanide ions are bridged simultaneously by their carboxyl groups from the opposite sides to form a 1D chain structure. The shape analysis of the eight-coordinated Dy analogue 5 highlights the coordination geometry of the distorted square antiprism (D). The solid-state luminescence of 2 and 4 was characterized. The static magnetic analysis of the Gd analogue 3 is indicative of the dominant weak intrachain antiferromagnetic interactions via the carboxylic ligands. Dynamic magnetic measurements for 5 revealed clear slow magnetic relaxation behaviour typical for single-molecule magnets (SMMs). Compound 5 represents a very rare example, reported as a mixed carboxylate bridged lanthanide SMM.