Structures and Structural Evolution of Sublayer Surfaces of Metal–Organic Frameworks

The structural characterization of sublayer surfaces of MIL‐101 is reported by low‐dose spherical aberration‐corrected high‐resolution transmission electron microscopy (HRTEM). The state‐of‐the‐art microscopy directly images atomic/molecular configurations in thin crystals from charge density projections, and uncovers the structures of sublayer surfaces and their evolution to stable surfaces regulated by inorganic Cr3(μ3‐O) trimers. This study provides compelling evidence of metal–organic frameworks (MOFs) crystal growth via the assembly of sublayer surfaces and has important implications in understanding the crystal growth and surface‐related properties of MOFs. The atomic‐scaled configurations of sublayer surfaces and their evolution of MIL‐101 crystals were directly imaged from their charge density projections by low‐dose spherical aberration corrected high‐resolution transmission electron microscopy. The surface transformation from a sublayer to a stable surface is fulfilled by the successive addition of hybrid Cr3(μ3‐O)‐(benzenedicarboxylate)x complexes, which is regulated by inorganic Cr3(μ3‐O) trimers.