Probing surface structure on two-dimensional metal-organic layers to understand suppressed interlayer packing

Two-dimensional metal-organic layers (MOLs) from alternatively connected benzene-tribenzoate ligands and Zr6(μ3-O)4(μ3-OH)4 or Hf6(μ3-O)4(μ3-OH)4 secondary building units can be prepared in gram scale via solvothermal synthesis. However, the reason why the monolayers did not pack to form thick crystals is unknown. Here we investigated the surface structure of the MOLs by a combination of sum-frequency generation spectroscopy, nanoscale infrared...