Thursday May the 21st at 11 am in PMC seminar room (Jean Mandel) :
Metal-organic frameworks (MOFs) offer remarkable versatility, characterized by tunable porosity, adaptable chemistry, and distinctive metal nodes. Alongside traditional MOF crystals and thin films, structurally analogous single-layered metal-organic coordination networks (MOCNs) have emerged as significant research subjects. Traditionally, structural characterization has relied primarily on X-ray diffraction techniques, with transmission electron microscopy (TEM) increasingly employed for molecular-level investigations.
Scanning probe microscopy (SPM) techniques have progressively expanded MOF characterization capabilities. Scanning tunneling microscopy (STM) under ultra-high vacuum (UHV) has been extensively utilized for molecular-resolution studies of MOCN monolayers, while atomic force microscopy (AFM) has characterized MOF thin films and crystals in air and liquid environments. However, SPM’s broad applicability has been constrained by significant technical challenges, including MOCN monolayer synthesis typically performed under UHV conditions and the necessity of MOF crystal immobilization for carrying out AFM measurements.
In this work, we address these fundamental methodological challenges through innovative approaches. The synthesis of MOCNs under ambient conditions and their characterization with STM at the liquid-solid interface is demonstrated, providing detailed structural insights related to the specific synthesis conditions used. A novel protocol for immobilizing MOF crystals on a solid substrate is also presented, which offers the unique advantage of enabling AFM characterization while maintaining the crystals in their growth solution, avoiding air exposure. AFM performed at the liquid-solid interface reveals the crystal structure of the target MOFs with molecular resolution.
The developed methodologies offer an unprecedented perspective on MOF characterization, facilitating a deeper understanding of structure-function relationships at the molecular level.