A Metallacryptand‐Based Manganese(II)–Cobalt(II) Ferrimagnet with a Three‐Dimensional Honeycomb Open‐Framework Architecture

Abstract

The design and synthesis of simple molecules containing paramagnetic metal centers that are able to self-assemble through metal-ligand interactions into supramolecular assemblies of increasing structural and magnetic complexity is a major challenge in modern (supra)molecular coordination chemistry and (supra)molecular magnetism.[1-4] Discrete zero-dimensional polynuclear coordination compounds as well as infinite one-, two-, or three-dimensional coordination polymers, also known as metal-organic frameworks (MOFs), [5] are included in this category. The overall structure and magnetic properties of the final nD products (n = 0-3) rely on the judicious choice of the metal building block, especially the substitution pattern and steric requirements of the bridging ligand and the electronic configuration and magnetic anisotropy of the metal ion. Such multidimensional species are of great importance in the so-called "bottom-up" approach to molecular magnetic materials, particularly the low-dimensional single-molecule (SMMs) or single-chain (SCMs) magnets and the higher-dimensionality moleculebased magnets, all of which have potential applications in information storage and processing nanotechnology. [6][7][8] Our strategy in this field is based on combining mono-, di-, and trinuclear late 3d transition metal complexes with a novel family of aromatic polyoxamato ligands as building blocks for the rational design of oxamato-bridged high-nuclearity coordination compounds and high-dimensionality coordination polymers with interesting magnetic properties. [9][10][11][12] In particular, the triple-stranded dinuclear cobalt(II) complex [Co 2 -(mpba) 3 ] 8À [mpba = 1,3-phenylenebis(oxamato)] enables the formation of double-propeller octanuclear coordination compounds with a metallacryptand core when acting as a hexakis(bidentate) ligand (Scheme 1, left). Such coordination compounds could constitute the basic structural unit for the construction of 3D open-frameworks with a "honeycomb" architecture and a (6,4) net topology (Scheme 1, right). Herein we report the synthesis, crystal structures, and magnetic properties of the oxamato-bridged heterobimetallic 3D compounds Li 5 [Li 3

Supramolecular coordination chemistry of aromatic polyoxalamide ligands: A metallosupramolecular approach toward functional magnetic materials

“…20a) [47,48]. In this case, the triple meta-substituted phenylene linkers ensure a ferromagnetic interaction between the oxamato-bridged ferrimagnetic planes that leads to a long-range 3D ferromagnetic order at T C = 3.5-13.5 K (Fig.…”

“…In this case, the triple meta-substituted phenylene linkers ensure a ferromagnetic interaction between the oxamato-bridged ferrimagnetic planes that leads to a long-range 3D ferromagnetic order at T C = 3.5-13.5 K (Fig. 20c) [47,48]. Moreover, the coercivity is relatively large in these M II 2 M II 3 3D MOPs (H c = 175-3750 Oe) (Table 3), as expected from the moderate to strong local magnetic anisotropy of the M II ions (M = Ni and Co).…”

“…In fact, the anionic M II 2 M II 3 3D MOPs host a large amount of crystallization water molecules and hydrated Li I countercations, which are either weakly bound to the host surface or form discrete chains aligned in the hexagonal channels (Fig. 20b) [47,48]. Indeed, one could envisage to remove the crystallization water molecules leaving unaltered their open-framework structure and readily available to selectively adsorb other small solvent (MeOH, EtOH, or PrOH) or gas (N 2 , H 2 , CH 4 , CO, or CO 2 ) molecules.…”

“…However, the presence of counterbalancing Li I ions as hosts within the pore system of the anionic open-framework structure accounts for its limited sorption capacity toward solvent molecules and gases [47].…”

Síntese, caracterização e estudo das propriedades magnéticas de um polímero de coordenação contendo cobalto(II) e cobre(II)

“…Podem-se citar alguns exemplos de sistemas infinitos como os polímeros de coordenação unidimensionais ou cadeias (1D), 7 os sistemas bidimensionais ou planos (2D), 8 as redes polimé-ricas tridimensionais entrelaçadas (3D) 9 e não entrelaçadas, 10 além de helicatos. 11 Por consequência, diferentes estruturas moleculares levam à obtenção de sistemas que podem apresentar diferentes propriedades além do magnetismo, 12 como condutividade, 13 propriedades ópticas, 14 redes porosas para absorção de gases, 15 dentre outros exemplos. 16 Portanto, a escolha do ligante é fundamental para o desenvolvimento de sistemas que apresentem propriedades de interesse que podem culminar, futuramente, num produto tecnologicamente aplicável.…”