Pressure-induced polymerization of 1,4-difluorobenzene towards fluorinated diamond nanothreads.

Pressure-induced polymerization (PIP) of aromatic molecules has emerged as an effective method for synthesizing various carbon-based materials. The selection of suitable functionalized molecular precursors is crucial for obtaining the desired structures and functions. In this work, 1,4-difluorobenzene (1,4-DFB) was selected as the building block for PIP. In situ high-pressure investigations of 1,4-DFB reveal a phase transition at approximately 12.0 GPa and an irreversible chemical reaction at 18.7 GPa. Structural analysis of the product and the kinetics of the reaction uncovered the formation of pseudo-hexagonal stacked fluoro-diamond nanothreads with linear growth. Compared to the crystal structure of benzene under high pressure, 1,4-DFB exhibits higher compression along the [001] axis. The anisotropic compression is attributed to the stronger H⋯π interactions along the [011̄] axis and the potential compression-inhibiting H⋯F interactions along the [100] and [010] axes, and it facilitates a possible reaction pathway along the [011̄] axis. This work emphasizes the crucial role of functionalization in modulating molecular stacking and influencing the reaction pathway.