Facile Orientational Control of M2L2P SURMOFs on < 100 > Silicon Substrates and Growth Mechanism Insights for Defective MOFs

Layer-by-layer growth of Cu-2(bdc)(2)(dabco) surface-mounted metal organic frameworks (SURMOFs) was investigated on silicon wafers treated with different surface anchoring molecules. Well-oriented growth along the [100] and [001] directions could be achieved with simple protocols: growth along the [100] direction was achieved by substrate pretreatment with 80 degrees C piranha, while growth along the [001] direction was enabled by only rinsing silicon with absolute ethanol. Growth along the [001] direction produced more homogeneous SURMOF films. Optimization to enhance [001]-preferred orientation growth revealed that small changes in the SURMOF growth sequence (the number of rinse steps and linker concentrations) have a noticeable impact on the final film quality and the number of misaligned crystals. This new straightforward protocol was used to successfully grow other layer pillar-type SURMOFs, including the growth of Cu-2(bdc)(2)(bipy) with simultaneous suppression of framework interpenetration.