Stabilization of O–Mn–O clusters (Mn5) in three dimensionally extended MOF structures: synthesis, structure and properties

Abstract

Four new three-dimensional Mn²⁺ ion-containing compounds have been prepared by employing a hydrothermal reaction between Mn(CH₃COO)₂·4H₂O, sulfodibenzoic acid (H₂SDBA), imidazole, alkali hydroxide and water at 220 °C for 1 day. The compounds have Mn₅ (1–4) clusters connected by SDBA, forming the three-dimensional structure. A time and temperature dependent study on the synthesis mixture revealed the formation of a one-dimensional compound, Mn(SDBA)(H₂O)₂, at lower temperatures (T ≤ 180 °C). The stabilization of the fcu related topology in the compounds is noteworthy. Magnetic studies indicate strong anti-ferromagnetic interactions between the Mn²⁺ ions within the clusters in the temperature range 75–300 K. The rare participation of a sulfonyl group in the bonding is important and can pave way for the design of new structures.