Metal-Organic Framework Thin Films Made Easily

Researchers have found a simple, fast way to make thin films of metal-organic frameworks, or MOFs (J. Am. Chem. Soc., DOI: 10.1021/ja307953m). The two-step technique allows chemists to control the film thickness and could work with many types of MOFs. Current methods for producing these films are time-consuming and aren’t compatible with MOFs that require harsh synthesis conditions, says Hiroshi Kitagawa, a chemist at Kyoto University, in Japan. He and his colleagues developed a new method to make thin films of MOFs containing copper and a porphyrin. The team started by preparing the MOF particles in N,N-diethylformamide and ethanol. Next, they dispersed the resulting MOF flakes in acetone or ethanol and then dripped the resulting suspension onto the surface of water in a beaker to produce a thin film. They transferred the layer to a solid substrate and repeated the process to create a film of desired thickness. In 10 minutes, the researchers could stack 100 layers of MOF sheets. By contrast, the traditional method took them 10 minutes to produce a single layer.