Tetratopic porphyrin-based MOFs represent a particularly interesting subclass of zirconium MOFs due to the occurrence of several divergent topologies. The control over the target topology is a demanding task and reports often show products containing phase contamination. We demonstrate how mechanochemistry can be exploited for controlling the polymorphism in 12-coordinated porphyrinic zirconium MOFs, gaining pure hexagonal (shp) PCN-223 and cubic (ftw) MOF-525 phases in 20-60 minutes of milling. The reactions are mainly governed by the milling additives and the zirconium precursor. In situ monitoring by synchrotron powder X-ray diffraction (PXRD) revealed that specific reaction conditions resulted in the formation of MOF-525 as an intermediate, which rapidly converted to PCN-223 upon milling. Electron spin resonance (ESR) measurements revealed significant differences between the spectra of paramagnetic centers in two polymorphs, showing a potential of polymorphic Zr-MOFs as tunable supports in spintronics applications. Metal-organic frameworks (MOFs) received wide attention due to their potential for applications in gas storage 1-3 and separation, 4,5 catalysis, 6,7 drug delivery, 8 light-harvesting, 9,10 and destruction of harmful compounds such as chemical warfare agents. 11 Their superior performance stems from the existence of pores and channels enabling easy access of substrates to the active sites inside the MOF crystals. The use of MOFs as heterogeneous catalysts and catalysts supports is broadened after the introduction of Zr-MOFs based on zirconium [Zr6(OH)4O4] 12+ oxo-clusters and carboxylate linkers, 12 which provided a way to overcome challenges related to the robustness of MOFs under humid, acidic or basic media. 11,13 They also drew significant interest in an area of MOF-polymorphism. Zr-MOFs based on tetratopic tetrakis(4-carboxyphenyl) porphyrin (TCPP) linkers displayed unprecedented flexibility in topological ordering. They are known to exist in six different topologies, 14,15-22 12-connected cubic ftw (MOF-525) 21 and hexagonal shp (PCN-223), 16 8-connected sqc (PCN-225), 17 csq (PCN-222/MOF-545), 19,21 and scu (NU-902), 15 and 6-connected she (PCN-224). 20 Recent studies have been focused on establishing different reaction

Encapsulation and confinement of fullerene guests in metal-organic frameworks (MOFs) lead to a novel class of crystalline fulleretic materials with unique physicochemical properties and a broad field of potential applications. The control over the amount of target guests confined in the MOF structure remains a significant challenge, which is particularly pronounced in the confinement of hardly accessible fullerene derivatives. The main strategies used in constructing fulleretic composites are limited by the solubility of components used and solvent versus guest competition for inhabitation of the framework voids. As mechanochemical procedures often overcome these issues, we developed here solvent-free processing by ball milling to gain control over the encapsulation of bulky and rigid C 60 -fullerene into a sodalite MOF with large cages and narrow cage-apertures. A rapid, green, efficient, and stoichiometry-controlled mechanochemical processing afforded four model C 60 @zeolitic-imidazolate framework 8 (ZIF-8) crystalline materials containing target 15, 30, 60, and 100 mol % of fullerene entrapped in the accessible cages of the model sodalite zeolitic-imidazolate framework 8 (ZIF-8), in stark contrast to the solution-based strategies that resulted in almost no loading. Varying the fullerene content affects the framework's vibrational properties, color and luminescence of the composites, and the electron-dose radiation stability. The computational and spectroscopic studies show that the fullerene is accommodated in the cage's center and that the cage-to-cage transport is a hardly feasible and energetically unfavored process. However, the fast release of C 60 molecules from ZIF-8 can be effectively controlled by the pH. The entrapment of fullerene molecules in ZIF-8 resulted in their effective isolation even in higher loadings, paving the way to other tunable porous fulleretics containing single-molecule magnets or nanoprobes available on low scales.

While desolvation process does not influence the magnetism of Ni-MOF-74, amorphization causes partial nickel(ii) spin-crossover from S = 1 to S = 0 and the decrease of the bulk magnetization.

A variety of structurally different complexes of the isopropyl-bis­(2-picolyl)­amine ( i Pr-bpa) ligand were prepared with ZnA2 and CuA2 salts (A = Br–, Br–/PF6 –, BF4 –/F–, ClO4 –). The choice of different counterion affected the stoichiometry, coordination number, geometry, and formation of geometrical isomers. Crystal structures of four Zn­(II) complexes, namely, two monomers ( mer -[Zn­( i Pr-bpa)­Br 2 ] and fac -[Zn­( i Pr-bpa)­Br 2 ]), one F–-bridged dimer ([Zn 2 (μ-F) 2 ( i Pr-bpa) 2 ]­(BF 4 ) 2 ), and one ML 2 complex ([Zn­( i Pr-bpa) 2 ]­(ClO 4 ) 2 ) were determined, and their solution structures were studied by NMR spectroscopy. For the ML 2 complex, relative stabilities of geometrical isomers were determined using density functional theory calculations. For Cu­(II) complexes, five crystal structures were determined, namely, two monomers ([Cu­( i Pr-bpa)­Br 2 ] and [Cu­( i Pr-bpa)­(ClO 4 ) 2 (H 2 O)]), a Br–-bridged dimer ([Cu 2 (μ-Br)­(Br) 2 ­( i Pr-bpa) 2 ]­(PF 6 )), a F–-bridged coordination polymer ([Cu­(μ-F)­( i Pr-bpa)] n (BF 4 ) n × nCH 3 OH), and a cyclic, CO3 2–-bridged trimer ([Cu 3 (tri-μ-CO 3 )­(ClO 4 ) 3 ­( i Pr-bpa) 3 ]­(ClO 4 )). The different crystallographic structures of Cu­(II) complexes are reflected in their different magnetic properties investigated by electron spin resonance spectroscopy and magnetic susceptibility measurements.