MOF thin films with bi-aromatic linkers grown by molecular layer deposition

Thin films of metal-organic frameworks (MOFs) are promising for a wide range of applications including membranes for separations and sensor materials in microelectronics. Growth of such thin films using atomic/molecular layer deposition (ALD/MLD) has recently been demonstrated; however, the range of examples is still narrow. Here, we expand the repertory of gas-phase MOF thin film synthesis by ALD/MLD to include 2,6-naphthalenedicarboxylate (2,6-NDC) and biphenyl-4,4 '-dicarboxylate (BP-4,4 '-DC) as organic linkers. The films, which were deposited using ZrCl4 and either H-2-2,6-NDC or H-2-BP-4,4 '-DC, were amorphous and formed crystalline MOF-structures when treated with acetic acid vapour at 160 degrees C. The film growth was investigated using in situ quartz crystal microbalance (QCM) measurements, and was in addition characterized using spectroscopic ellipsometry (SE), photoluminescence (PL), scanning electron microscopy (SEM), grazing incidence X-ray diffraction (GIXRD) and X-ray reflectivity (XRR). We further performed introductory investigations into a selection of possible future applications of these films, due to their porosity, luminescent and antibacterial properties. Expanding the repertory of MOF synthesis by ALD/MLD to include longer linkers such as 2,6-NDC and BP-4,4 '-DC enables synthesis of thin films with a larger range of pore sizes.