Twisted-stacking MOF patterns with tailorable circularly polarized luminescence properties and encryption applications

Optical active metal-organic frameworks (MOFs) with circularly polarized luminescence (CPL) functionalities, have recently gained extensive research interest. However, the luminescence dissymmetry factors (g_lum) of these materials are generally small, and the lack of patterning ability for most optical active MOFs greatly hinders their practical applications. Herein, we report a strategy to design twisted-stacking MOF patterns with a high g_lum (~0.4) and tailorable CPL performance by the combination of brush coating, bottom-up heteroepitaxial growth and twisted-stacking techniques. Specifically, two-dimensional (2D) programmable patterns of highly oriented MOF films could be achieved by the heteroepitaxial growth from pre-aligned Cu(OH)₂ nanowire (NW) templates. The oriented MOF patterns could be functionalized with fluorescent dyes, offering characteristic anisotropic photoluminescent response. After another similar highly oriented MOF layer was deposited on top of the above MOF/dye patterns (in a twisted fashion) as a phase retarder, a chiroptical response could be generated. This design not only allows the fabrication of arbitrary programmable optical active MOF patterns with enhanced g_lum, but also enables precise regulation of CPL performance within the patterns, favoring the implementation of the miniaturized chiroptical devices, information encryption and storage.