The drug olsalazine (H4olz) was employed as a ligand to synthesize a new series of mesoporous metal–organic frameworks that are expanded analogues of the well-known M2(dobdc) materials (dobdc4– = 2,5-dioxido-1,4-benzene­dicarboxylate; M-MOF-74). The M2(olz) frameworks (M = Mg, Fe, Co, Ni, and Zn) exhibit high surface areas with large hexagonal pore apertures that are approximately 27 Å in diameter. Variable temperature H2 adsorption isotherms revealed strong adsorption at the open metal sites, and in situ infrared spectroscopy experiments on Mg2(olz) and Ni2(olz) were used to determine site-specific H2 binding enthalpies. In addition to its capabilities for gas sorption, the highly biocompatible Mg2(olz) framework was also evaluated as a platform for the delivery of olsalazine and other encapsulated therapeutics. The Mg2(olz) material (86 wt % olsalazine) was shown to release the therapeutic linker through dissolution of the framework under simulated physiological conditions. Furthermore, Mg2(olz) was used to encapsulate phenethylamine (PEA), a model drug for a broad class of bioactive compounds. Under simulated physiological conditions, Mg2(olz)­(PEA)2 disassembled to release PEA from the pores and olsalazine from the framework itself, demonstrating that multiple therapeutic components can be delivered together at different rates. The low toxicity, high surface areas, and coordinatively unsaturated metal sites make these M2(olz) materials promising for a range of potential applications, including drug delivery in the treatment of gastrointestinal diseases.

Only a few four‐coordinated Co2+‐complexes show single‐molecule magnet (SMM) properties without an applied dc field. Common for those is a large magnetic anisotropy generated by the close proximity of the dxy4pt and dx2-y2 orbitals. This type of magnetic anisotropy is strongly correlated with the extent of structural distortion from ideal tetrahedral towards linear coordination. Quantification of the governing magneto‐structural correlations is hence crucial for the development of better SMMs. For this purpose, we synthesized and analyzed four significantly distorted tetrahedral cobalt complexes that exhibit extremely large magnetic anisotropies and slow relaxation of magnetization in zero field. The N−Co−N bite angles vary from 70.8 to 72.7°, and magnetic measurements show strong anisotropy with D‐values in the range from - 75 to - 114 cm−1. Ab initio calculations supported the experimental results and highlighted a significant increase of D up to - 141 cm−1, correlated with the reduction of the energy difference between the dxy4pt and dx2-y2 orbitals. Based on these magneto‐structural correlations and in contrast to the current assumption that the smaller bite angle is the better, we predict that with an ideal bite angle in the range from 76–78° in distorted Co(N2R)2 complexes, the energy difference between the two important d‐orbitals is at a minimum and hence the magnetic anisotropy is maximized.

Two series a and b of 3d metal based complexes 1–4 [MII{(4-R-NCOC6H4)2CH}2], (with M = Mn (1), Fe (2), Co (3), Ni (4) and R = H (a) or Me (b)) were synthesised and structurally as well as magnetically characterized.

The (hetero)­bimetallic complexes [Cl2Mn­(NtBu)2S­(tBuN)2Mn­{ClLi­(THF)3}2] (1), [(acac)­Co­(NtBu)2S­(tBuN)2Co­(acac)] (2), and [(acac)­Co­(NtBu)2S­(tBuN)2Li­(THF)2] (3), with THF = tetrahydrofuran and acac = acetylacetonate [H2C­(C­(O)­Me)2], were synthesized and investigated for their magnetic properties. While the two different MnII sites in 1 gave a weak coupling of J = −1.00 cm–1, we could observe an appreciable antiferromagnetic coupling of J = −6.08 cm–1 between the two CoII cations in 2, proving the tetraimido sulfate anion to be a challenging but promising linker to enhance magnetic communication between paramagnetic centers. The heterobimetallic complex 3 seems a versatile platform for magnetically interesting d/d, f/d, or f/f mixed-metal complexes.

From the sodium sodate precursor [(Na­(thf)6]­[Na­{(4-Me-NCOC6H3)2CH}2] (1) three isostructural dinuclear lanthanide complexes [(μ-Cl)­LnIII{(4-MeNCOC6H3)2CH}2]2 with Ln = Gd (2), Dy (3), and Er (4) based on the N,N′-chelating monoanionic bis­(4-methylbenzoxazol-2-yl)­methanide ligand (titled “Mebox”) were synthesized and characterized by X-ray diffraction and magnetic measurements. The sodium precursor 1 was analyzed via X-ray diffraction and diffusion-ordered NMR spectroscopy experiments (DOSY-NMR) in order to investigate its aggregation in solution and the solid state. The sodium analog [(thf)3Na­(NCOC6H4)2CH] (1′) based on the bis­(benzoxazol-2-yl)-methanide ligand (titled “box”) was prepared and analyzed for comparison reasons. From the lanthanide derivatives 2–4, the DyIII complex 3 displays slow relaxation of magnetization at zero field, with a relaxation barrier of U = 315.7 cm–1. The coupling strength between the two lanthanide centers was estimated with the GdIII equivalent 2, giving a weak antiferromagnetic coupling of J = −0.035 cm–1.