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Discrete molecular species that can perform certain functions in response to multiple external stimuli constitute a special class of multifunctional molecular materials called smart molecules. Herein, cyanido-bridged coordination clusters {[FeII (2-pyrpy)2 ]4 [MIV (CN)8 ]2 }⋅4 MeOH⋅6 H2 O (M=Mo (1 solv), M=W (2 solv) and 2-pyrpy=2-(1-pyrazolyl)pyridine are presented, which show persistent solvent driven single-crystal-to-single-crystal transformations upon sorption/desorption of water and methanol molecules. Three full desolvation-resolvation cycles with the concomitant change of the host molecules do not damage the single crystals. More importantly, the Fe4 M2 molecules constitute a unique example where the presence of the guests directly affects the pressure-induced thermal spin crossover (SCO) phenomenon occurring at the FeII centres. The hydrated phases show a partial SCO with approximately two out-of-four FeII centres undergoing a gradual thermal SCO at 1 GPa, while in the anhydrous form the pressure-induced SCO effect is almost quenched with only 15 % of the FeII centres undergoing high-spin to low-spin transition at 1 GPa.

We report a non-MOF crystalline material {[Mn(imH)]2[Mo(CN)8]}n (imH = imidazole) with exceptional water sorption properties and a very large breathing effect accompanied by an outstanding stability and cyclability – properties that are absolutely unique for this class of compounds (Prussian Blue Analogs). Some previously published PBAs indeed show some sorption properties, but their cyclability is extremely limited - usually 1-3 cycles - followed by significant decomposition/amorphization. Our compound can be cycled more than 50 times without any fatigue and the sorption/desorption proceeds through four different crystal phases, which we have fully characterized structurally enabling the complete understanding of the sorption and breathing mechanism in this material - an achievement rarely reported for MOFs or PBAs. The unique structure of {[Mn(imH)]2[Mo(CN)8]}n enables very strong coupling of its exceptional water sorption performance with the magnetic and photomagnetic properties of the framework, e.g. the sorption process can be followed by in-situ EPR spectroscopy with huge changes in the EPR signal intensity depending on the hydration level.

While metal–organic frameworks (MOFs) are at the forefront of cutting-edge porous materials, extraordinary sorption properties can also be observed in Prussian Blue Analogs (PBAs) and related materials comprising extremely short bridging ligands. Herein, we present a bimetallic nonporous cyanide-bridged coordination polymer (CP) {[Mn(imH)]2[Mo(CN)8]}n (1Mn; imH = imidazole) that can efficiently and reversibly capture and release water molecules over tens of cycles without any fatigue despite being based on one of the shortest bridging ligands known – the cyanide. The sorption performance of {[Mn(imH)]2[Mo(CN)8]}n matches or even outperforms MOFs that are typically selected for water harvesting applications with perfect sorption reversibility and very low desorption temperatures. Water sorption in 1Mn is possible due to the breathing effect (accompanied by a dramatic cyanide-framework transformation) occurring in three well-defined steps between four different crystal phases studied structurally by X-ray diffraction structural analysis. Moreover, the capture of H2O by 1Mn switches the EPR signal intensity of the MnII centres, which has been demonstrated by in situ EPR measurements and enables monitoring of the hydration level of 1Mn by EPR. The sorption of water in 1Mn controls also its photomagnetic behavior at the cryogenic regime, thanks to the presence of the [MoIV(CN)8]4− photomagnetic chromophore in the structure. These observations demonstrate the extraordinary sorption potential of cyanide-bridged CPs and the possibility to merge it with the unique physical properties of this class of compounds arising from their bimetallic character (e.g. photomagnetism and long-range magnetic ordering)., A cyanide-bridged coordination polymer {[Mn(imH)]2[Mo(CN)8]}n shows exceptional water sorption properties, very large breathing effect and outstanding stability – properties that are unique for this class of compounds – Prussian blue analogs.

Zeolite monolayers in solution, reported recently for the framework MWW, enable unprecedented synthetic capabilities that include preparation of molecularly intimate mixtures of different zeolite topologies. As a demonstration, MWW-MFI hybrid materials were synthesized by two methods: in-situ crystallization of MFI by adding the template and silica to solutions of MWW monolayers obtained from the zeolite MCM-56, and ex-situ by mixing the solutions of MWW layers with MFI crystals. Catalytic activity of the mixtures was similar to undiluted pure MWW despite high content of siliceous MFI, which was inert. This suggests that pure MWW layers do not provide optimal packing and accessibility of active sites and can be more efficiently utilized in combination with other components. The mixture of MCM-56 and MFI crystals was 50% less active. Practical benefits may be possible by combining frameworks with different types of activity in catalysis and sorption applications. The mixtures were characterized by the standard methods: X-ray powder diffraction, TEM and SEM imaging, gas adsorptions and FTIR, which showed properties of both the MWW and MFI features with high acid activity and porosity.