Unveiling Energy Transfer Mechanisms in Nanographene-Incorporated Metal-Organic Frameworks

Nanographenes are a class of extended pi-conjugated molecules with great potential for photophysical and electrochemical properties. However, most nanographenes show self-aggregation due to their strong pi-pi interaction, resulting in structures barely possessing any open pi surface. We find that metal-organic frameworks (MOFs) can be an ideal platform to construct periodic arrays and pores with isolated large pi-conjugated surfaces by avoiding undesired pi-pi interactions between the nanographene molecules. Here, we report a multivariate series of nanographene-incorporated MOFs, UMOF-2-X, utilizing the graphene-like hexatopic organic linkers, hexaphenylethynylbenzene (HPB) and hexabenzocoronene (HBC), through a mixed-linker strategy. Remarkably, UMOF-2 inhibits the occurrence of linker-to-metal charge transfer to Cu metal and shows efficient energy transfer between HPB and HBC linkers.