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Wuttke Group in Berkely

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From the 15th of July to the 26th of June the Wuttke Group has been visiting UC Berkley. During this stay we had the privilege to work in close cooperation with Omar Yaghi and his group. We took this opportunity to adapt to the American lifestyle both work related and food wise, to make new friends and widen our social circle. Given the chance, we didn’t only educate ourselves but also visited San Francisco and its sights. All in all, this ideal mixture paired with many efficient discussion resulted in fruitful progress in work.

Violation of Archimedes’ Principle in Metal-Organic Framework Nanoparticles

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Archimedes’ principle states that the weight of a submerged body is reduced by the weight of the fluid it displaces, implying that buoyancy can be described fully in terms of geometry and physics. In our Small article we show that porous nanoparticles can violate this assertion. Direct weighing of porous Metal-organic framework (MOF) nanoparticles in different binary solvents using nanomechanical Mass Correlation Spectroscopy (MCS) reveals that the apparent mass density of these particles exhibits a pronounced dependence on the chemical identity of the solvent molecules. Interestingly, the pore size of the nanoparticles is much too large for the exclusion of small solvent molecules by steric hindrance. Although MOF materials are known for their selective binding of molecules in the gas phase, selective permeation to different solvent components has not previously been measured. Our findings suggest that the interactions between the solvent components and the internal MOF surface create a complex partitioning pattern, which may substantially differ from the solvent composition.