Title: Exploring the effect of bulky linkers on MOF host-guest interactions

Abstract

Aromatic ligands, with polycarboxylate or multitopic functionalities, govern the synthetic chemists’ toolbox when forming metal-organic frameworks (MOFs) due to their rigid nature, commercial availability, and their variable coordination modes. Conversely, despite their extensive success in creating a rich foundation for MOF development, restriction to solely phenyl interactions within adsorbates represents a possible limitation and reduced variation in the pore chemical environment of the materials.1 Our research explores how aliphatic 3D-linkers in MOFs can influence the pore environment and overall structural properties of MOFs. Our team explores linkers such as cubane-1,4-dicarboxylic acid (H2cdc), bicyclo[1.1.1]pentane-1,3-dicarboxylic acid (H2pdc) and p-carborane-1,12-dicarboxylic acid (H2pcarb). These linkers are structurally similar to benzene-1,4-dicarboxylic acid (H2bdc) and therefore can be used to create analogues of well-known bdc MOF systems, to be used for direct host-guest behavioural comparisons. Using this approach, single and multicomponent MOFs have been synthesised, where the significant differences between these systems lie in the host-guest interactions between the MOF and gaseous and hydrocarbon guests.

This presentation will give an overview of these host-guest interactions within 3DL-MOFs (3D-linker MOFs) and how they differ from their aromatic analogues. Through the incorporation of 3D-linkers into prominent MOF architectures, we demonstrate the striking effects a contoured, aliphatic pore environment has on gas and hydrocarbon adsorption, compared with its aromatic counterpart, and explore the potential separation capacities these frameworks may pose.1,2,3 Furthermore, structural studies using neutron and synchrotron powder diffraction highlight the differences relating to negative thermal expansion behaviours between these MOF systems. These can be attributed to a multitude of properties relating to the linker, including influencing the pore size and shape, chemical environment and structural rigidity.

References
1Macreadie, L.K et al. ACS Appl. Mater. Interfaces 2021, 13, 30885.
2Macreadie, L.K et al. Angew. Chem. Int. Ed. 2020, 59, 6090.
3Macreadie L.K et al. J. Amer. Chem. Soc. 2019, 141, 3828.

Lauren Macreadie Bio

Dr Lauren Macreadie is a DECRA fellow at the University of Sydney and investigates how porous materials can be used to solve our key energy questions around hydrogen storage, transport and generation. Following the completion of her PhD at the CSIRO and Monash University in 2016, she worked at Trinity College in Dublin, Ireland, on water splitting MOF systems, followed by research with the CSIRO in Melbourne on MOFs as adsorbents for respiratory canisters for the Defense Science and Technology group. Lauren then transitioned to independent research at the CSIRO, followed by a move to Massey University in New Zealand as a Chemistry Lecturer. She recently moved to the University of Sydney where she investigates functional MOF materials on her DECRA fellowship.