The force of MOFs: the potential of switchable metal-organic frameworks as solvent stimulated actuators.

We evaluate experimentally the force exerted by flexible metal-organic frameworks through expansion for a representative model system, namely MIL-53(Al). The results obtained are compared with data collected from intrusion experiments while molecular simulations are performed to shed light on the re-opening of the guest-loaded structure. The critical impact of the transition stimulating medium on the magnitude of the expansion force is demonstrated.

Switchable Conductive MOF-Nanocarbon Composite Coatings as Threshold Sensing Architectures.

Switchable metal-organic frameworks (MOFs) showing pronounced and stepwise volume changes as a response toward external stimuli such as partial pressure changes were integrated into electron conductive composites to generate novel threshold sensors with pronounced resistivity changes when approaching a critical partial pressure. Two "gate pressure" MOFs (DUT-8(Ni), DUT = Dresden University of Technology, and ELM-11, ELM = Elastic Layer-structured MOF) and one "breathing" MOF (MIL-53(Al), MIL = Material Institute Lavoisier) are shown to cover a wide range of detectable gas concentrations (∼20-80%) using this concept. The highest resistance change is observed for composites containing a percolating carbon nanoparticle network (slightly above the percolation threshold concentration).

Optical Sensors Using Solvatochromic Metal-Organic Frameworks.

A series of copper and 1,3-phenylebis(azanetriyl)tetrabenzoate based MOFs were obtained by postsynthetic modification of DUT-71 (DUT = Dresden University of Technology) using various nitrogen containing, neutral ligands to afford the compounds DUT-74, DUT-95, DUT-112, and DUT-114. The structure of the new MOFs DUT-112 and DUT-114 was solved from synchrotron X-ray single-crystal diffraction data. Both structures are tetragonal (P4/mnc) but differ slightly in the lattice parameters.