Tuning Thermal Expansion in Metal–Organic Frameworks Using a Mixed Linker Solid Solution Approach

Abstract

Several metal−organic frameworks are known to display negative thermal expansion (NTE). However, unlike traditional NTE material classes, there have been no reports where the thermal expansion of a MOF has been tuned continuously from negative to positive through the formation of single-phase solid solutions. In the system Zn-DMOF-TM x , Zn 2 [(bdc) 2−2x (TM-bdabco) 2x ][dabco], the introduction of increasing amounts of TM-bdc, with four methyl groups decorating the benzene dicarboxylate linker, leads to a smooth transition from negative to positive thermal expansion in the a−b plane of this tetragonal material. The temperature at which zero thermal expansion occurs evolves from ∼186 K for the Zn-DMOF parent structure (x = 0) to ∼325 K for Zn-DMOF-TM (x = 1.0). The formation of mixed linker solid solutions is likely a general strategy for the control of thermal expansion in MOFs.

A new route to porous metal–organic framework crystal–glass composites

“…The thermal expansivities of the unit cell of numerous crystalline MOF structures have been reported from changes to the crystal unit cell determined by renement of variable temperature X-ray data. [35][36][37] However, it can be argued that the macroscopic thermal expansion of the formed bulk material is just as important. 38 This has been rarely reported for MOFs, due to problems in forming bulk samples for measurement by thermomechanical analysis (TMA).…”

Unravelling thermal stress due to thermal expansion mismatch in metal–organic frameworks for methane storage

“…13,19 While this anomalous behavior could be benecial for the development of zero-expansion composites for highly-specialized applications, 20 it poses some additional design constraints when in contact with conventional materials. Various practical ways of controlling the thermal expansion behavior of MOFs have already experimentally been demonstrated: retrotting, 21 adsorption of guest molecules, 17,22,23 changing the organic linkers or metal ions, 17,24,25 adding functional groups, 16 incorporating defects, 26 etc. Computational studies corroborate these ndings.…”

Significantly lowered activation energy in proton conductor by Mg substitution in a layered Ni metal–organic framework

“…Solid-solution type MOFs have homogeneously mixed metal ions or ligands in MOF structures, who can continuously regulate the ion-ligand charge transfer and lattice strain in wide ranges, and intrinsically adjust the proton conducting performances of MOFs. 7 Therefore, the formation of solid-solution type MOFs may be a rational strategy to enhance the proton conductivity of MOFs. The proton conducting ability of bimetal MOFs was reported very recently, 8 to our best knowledge, the homogeneous solid-solution type MOFs are rarely investigated.…”