Thermal Analysis and Heat Capacity Study of Metal-Organic Frameworks

Thermal stability and heat capacity of several metal-organic frameworks and their corresponding organic ligands have been investigated systematically using TGA-DSC technique. A simple notation system was created to present the local coordination environment around metal atoms in a secondary building unit (SBU). The heat capacity contributions of organic functional groups and SBUs were examined using the group-contribution method. Our results suggest that the thermal stability of MOFs is determined by the coordination number and local coordination environment instead of framework topology. Specific heat capacities (C-p) of all examined MOFs exhibit comparable values as other solids including carbon nanotubes, zeolites, and minerals. The molar heat capacity contributions of SBUs in MOFs indicate similar abnormal thermal behavior as negative thermal expansion of MOFs.