Electron-beam-induced structural degradation in two representative 2D MOFs: a ligand-dependent comparison

Abstract

Two-dimensional metal-organic frameworks (2D-MOFs) are promising for separations, sensing, and nano-optoelectronics. However, their integration with electron beam fabrication and imaging is limited by beam-induced structural damage. Here, we show that ligand-chemistry drives plane-specific electron-beam responses in two distinct 2D-MOFs with planar-porphyrinic-carboxylate and tetrahedral imidazolate coordination. Using low-dose serial electron diffraction at 300 kV, we quantify degradation pathways and critical doses for Zn-TCPP (porphyrinic-carboxylate) and Zn2(benzimidazolate)4. Zn-TCPP exhibits a two-stage evolution in which early ligand-assisted rearrangement transiently strengthens selected Bragg planes before the pristine unit cell collapses at higher cumulative dose. In contrast, Zn2(benzimidazolate)4 undergoes a direct transition to amorphization consistent with progressive Zn-N4 breakdown. The degradation mechanism, along with extracted ligand-resolved dose thresholds, practical windows for low-dose transmission electron microscopy, defect engineering, and electron-beam lithography (EBL), with conversions to standard exposure units, is provided. These results reframe the electron-beam from liability to design tool and low-dose characterization of 2D-MOFs.