Mechanical Exfoliation of Multilayer Pseudohalogen-Bridged Nanosheets

The development of nanolayered materials is one of the greatest challenges in nanoscience. Until now, pseudohalogen-bridged nanosheets using the mechanical exfoliation method have not been reported. A state-of-the-art material, {[Fe^II(3-acetylpyridine)₂][Hg^II(μ-SCN)₄]}_n (1), has been developed to achieve the goal. The compound forms a two-dimensional (2D) coordination polymer with weak out-of-plane van der Waals interactions and has an intrinsic tendency to form shear planes perpendicular to the crystallographic c-direction. These structural features predispose 1 to mechanical exfoliation realized by employing the “Scotch-tape method”. As a result, nanosheets were fabricated and characterized by digital optical microscopy, scanning electron microscopy, and atomic force microscopy. The nanosheets were found to have a minimum thickness of ∼15 nm and a lateral size of several micrometers. As the first example of thiocyanato-bridged coordination nanosheets, these materials extend the scope of 2D materials and potentially pave the way toward developing nanolayered materials.