Overall, we show the first example of the synthesis of non-vdW 2D MOF by developing UiO-66 films with tunable thicknesses in the range of 0.5 to 2 unit cells. Remarkably, this was achieved via green, sustainable chemistry which is also user-friendly eliminating the need for organic solvents, high-temperature reactors, and long synthesis time. With this approach, oriented UiO-66-NH2 films with a thickness of just a few nanometers could be prepared, compared to the mostly micrometer-thick film in the literature. Pinholefree non-vdW 2D UiO-66 films were stable in salt solution and yielded attractive ion-ion selectivity. Our work underscores that inplane growth of non-vdW MOFs can be achieved by careful screening of growth conditions. This highlights the potential to transform non-vdW MOFs to a 2D morphology which will greatly advance the application of MOF films. ), where x can be NH2 or H. (c) The comparison of reaction time and temperature used in this study and those reported in the literatures (Table ). (d) AFM image and (e) the corresponding height profile of 5 min growth of non-vdW 2D UiO-66-NH2 film, acquired from the white box in (d). (f) Zr 3d and (g) N 1s XPS spectra from non-vdW 2D UiO-66-NH2 films with a growth time of 5 min. (h) The ratio of N to Zr of non-vdW 2D UiO-66-NH2 films. The error bars were calculated from the standard deviation of XPS measurements from three different regions.