Preparation and applications of two-dimensional crystals based on organic or metal-organic materials

Besides graphene and transitional metal dichalcogenide nanosheets which have aroused tremendous research interest over the last decade, recently, two-dimensional (2D) organic or metal-organic nanosheets have also attracted increasing research interest. These ultrathin nanomaterials possess the long range structural order, the tunable surface properties, and/or controllable porosity, making them promising in a wide range of applications, such as electronics, optoelectronics, catalysis, molecular separation and so on. This review article aims to provide a brief overview on free-standing 2D nanosheets of organic or metal-organic materials that have been reported so far, especially focusing on their synthetic methods and possible applications.