A Singular Molecule-to-Molecule Transformation on Video: The Bottom-Up Synthesis of Fullerene C-60 from Truxene Derivative C60H30

Journal article, 2021

Singular reaction events of small molecules and their dynamics remain a hardly understood territory in chemical sciences since spectroscopy relies on ensemble-averaged data, and microscopic scanning probe techniques show snapshots of frozen scenes. Herein, we report on continuous high-resolution transmission electron microscopic video imaging of the electron-beam-induced bottom-up synthesis of fullerene C-60 through cyclodehydrogenation of tailor-made truxene derivative 1 (C60H30), which was deposited on graphene as substrate. During the reaction, C60H30 transformed in a multistep process to fullerene C-60. Hereby, the precursor, metastable intermediates, and the product were identified by correlations with electron dose-corrected molecular simulations and single-molecule statistical analysis, which were substantiated with extensive density functional theory calculations. Our observations revealed that the initial cyclodehydrogenation pathway leads to thermodynamically favored intermediates through seemingly classical organic reaction mechanisms. However, dynamic interactions of the intermediates with the substrate render graphene as a non-innocent participant in the dehydrogenation process, which leads to a deviation from the classical reaction pathway. Our precise visual comprehension of the dynamic transformation implies that the outcome of electron-beam-initiated reactions can be controlled with careful molecular precursor design, which is important for the development and design of materials by electron beam lithography.