Structures and magnetic properties of Mn and Co inorganic–organic frameworks with mixed linear dicarboxylate ligands

Abstract

The structures and magnetic properties of two transition metal frameworks that feature a mixture of two linear dicarboxylate ligands are reported. Compoundscontain a mixture of succinate and adipate ligands but adopt significantly different structures. Compound 1 features layers of MnO 6 dimers, intraconnected by carboxylate groups, with neighbouring dimers connected to each other via the adipate ligands in one direction and succinate ligands in the other. Extensive hydrogen bonding in the third dimension provides the main force holding layers together. Framework 2 has inorganic layers of CoO 6 octahedra arranged into rings of 14 members each, with adipate ligands providing inter-layer connectivity. The structures of these two compounds are compared to Mn and Co dicarboxylate frameworks containing only one type of organic ligand, including Co(C 6 H 8 O 4 ), compound 3, whose structure is reported in this work for the first time; they are found to be significantly different from those that form under similar conditions. Both compounds order magnetically near 2 K. Compound 1 is an antiferromagnet, in which the intra-dimer coupling dominates the magnetic behaviour, while framework 2 is most likely a canted antiferromagnet. Both compounds undergo magnetic phase transitions with increasing applied magnetic fields, at 14 kOe and 0.35 kOe in 1 and 2, respectively. The transition in the Mn compound is a simple spin flop but in the Co compound the suppression of the long range ordered state is also accompanied by the elimination of the ferromagnetic component of its magnetic interactions.

Magnetoelastic coupling in the cobalt adipate metal–organic framework from quasi-harmonic lattice dynamics

“…8 A number of MOFs have already been synthesized with interesting magnetic properties such as low-dimensional magnetism, [8][9][10] spin-flop transitions, 11 magnetocaloric effects [12][13][14] and magnetoelastic coupling. The magnetic coupling between two transition metal atoms is sensitive to the length and geometry of the super-exchange pathway, which can be varied by the rich choice of organic building blocks.…”

Cobalt adipate, Co(C6H8O4): antiferromagnetic structure, unusual thermal expansion and magnetoelastic coupling

“…1 More recently denser frameworks have attracted signicant attention for exhibiting low dimensional and meta-magnetic behaviour, multiferroicity and strong magnetocaloric effects. [2][3][4][5][6] In particular the transition metal dicarboxylate frameworks have shown a wide range of low dimensional and eld dependent magnetic behaviour. [2][3][4]6,7 Compounds in this family exhibit two dimensional magnetic order in structures that can readily be made into nanosheets, 3,8 while related materials transform from antiferromagnetic to ferromagnetic phases or feature spin op transitions with applied magnetic elds.…”

“…[2][3][4][5][6] In particular the transition metal dicarboxylate frameworks have shown a wide range of low dimensional and eld dependent magnetic behaviour. [2][3][4]6,7 Compounds in this family exhibit two dimensional magnetic order in structures that can readily be made into nanosheets, 3,8 while related materials transform from antiferromagnetic to ferromagnetic phases or feature spin op transitions with applied magnetic elds. 4,6 The magnetic properties of frameworks depend on their precise magnetic interactions and a deeper understanding of these is required to underpin their future development.…”

Transition metal phosphite complexes: from one-dimensional chain, two-dimensional sheet, to three-dimensional architecture with unusual magnetic properties

“…S15 †), consistent with an antiferromagnetic phase. 22 Further inspection reveals that the isothermal magnetisation curve features a slightly sigmoidal shape possessing a critical field of about 3 T, which can be estimated by the calculated derivative dM/dH curve (Fig. 4).…”