The molecular building block approach was employed effectively to construct a series of novel isoreticular, highly porous and stable, aluminum-based metal–organic frameworks with soc topology. From this platform, three compounds were experimentally isolated and fully characterized: namely, the parent Al-soc-MOF-1 and its naphthalene and anthracene analogues. Al-soc-MOF-1 exhibits outstanding gravimetric methane uptake (total and working capacity). It is shown experimentally, for the first time, that the Al-soc-MOF platform can address the challenging Department of Energy dual target of 0.5 g/g (gravimetric) and 264 cm3 (STP)/cm3 (volumetric) methane storage. Furthermore, Al-soc-MOF exhibited the highest total gravimetric and volumetric uptake for carbon dioxide and the utmost total and deliverable uptake for oxygen at relatively high pressures among all microporous MOFs. In order to correlate the MOF pore structure and functionality to the gas storage properties, to better understand the structure–property relationship, we performed a molecular simulation study and evaluated the methane storage performance of the Al-soc-MOF platform using diverse organic linkers. It was found that shortening the parent Al-soc-MOF-1 linker resulted in a noticeable enhancement in the working volumetric capacity at specific temperatures and pressures with amply conserved gravimetric uptake/working capacity. In contrast, further expansion of the organic linker (branches and/or core) led to isostructural Al-soc-MOFs with enhanced gravimetric uptake but noticeably lower volumetric capacity. The collective experimental and simulation studies indicated that the parent Al-soc-MOF-1 exhibits the best compromise between the volumetric and gravimetric total and working uptakes under a wide range of pressure and temperature conditions.

Structure/properties relationships for a series of isostructural (MOFs) with thesoctopology were explored for various gas separation applications.

Highlights Stable fluorinated Metal Organic Frameworks with tunable structural properties;  Structural properties of MFFIVE-1-Ni with relation to C2+ adsorption were unveiled;  Substitution of Nb 5+ by Al 3+ led to improved separation for C2H2/C2H4:1/99 system;  NbOFFIVE-1-Ni shows unprecedented CO2/C2+ selectivity in favor of CO2;  Substitution of Nb 5+ by Al 3+ affects the mechanism involved in C2+ separations; Graphical abstract (Two fluorinated ultra-microporous materials, NbOFFIVE-1-Ni and AlFFIVE-1-Ni with [NbOF5] 2and [AlF5] 2building block acting as inorganic pillars, respectively, result in much different adsorption behavior for CO2 and C2+. NbOFFIVE-1-Ni with confined pore space exhibit much higher CO2 uptake amount at low pressures, by contrast, AlFFIVE-1-Ni with potential open metal sites in pore spaces exhibit relatively larger pore volume, leading to enhanced C2H2 adsorption performance at low pressures and improved C2H2/C2H4 separation selectivity.