Self-Assembly, Rearrangement, and Disassembly of {Cr₆} Horseshoe Oligomers

Molecular assemblies are commonly found in biological systems, and designing synthetic mimics of these is a challenge for modern chemistry. Here, we apply ion mobility mass spectrometry (IM-MS), density functional theory (DFT), and mass-selective electrospray ion beam deposition followed by low-temperature scanning tunneling microscopy (STM) to decipher the self-assembly, rearrangement, and disassembly processes of {Cr₆}_n horseshoe oligomers (n = 1-5). Activated tandem IM-MS reveals the oligomer disassembly in detail, highlighting the stability of the dimer unit. When n = 2 and n = 3 oligomers are deposited on surfaces, we observe the rearrangement of dimers and trimers to dimers of dimers, and at higher coverages, the formation of an unexpected hexagonal-like network. In its entirety, the experimental and computational data provide a convincing framework for the analysis of supramolecular assembly processes in noncrystalline phases that could be used in future design strategies.