Phase transitions and polymerization of CH-CF cocrystal under extreme conditions

Wang, Y.*; Wang, L.*; Zheng, H.*; Li, K.*; Andrzejewski, M.*; Hattori, Takanori; Sano, Asami; Katrusiak, A.*; Meng, Y.*; Liao, F.*; et al.

Journal of Physical Chemistry C, 120(51), p.29510 - 29519, 2016/12

https://doi.org/10.1021/acs.jpcc.6b11245

Pressure-induced polymerization (PIP) of aromatic molecules can generate saturated carbon nanostructures. As a strongly interacted - stacking unit, the CH-CF adduct is widely applied in supramolecular chemistry, and it provides a good preorganization for the PIP. Here we investigated the structural variation of CH-CF cocrystal and the subsequent PIP process under high pressure. Four new molecular-complex phases V, VI, VII, and VIII have been identified and characterized by the in situ Raman, IR, synchrotron X-ray, and neutron diffraction. The phase V is different from the phases observed at low temperature, which has a tilted column structure. Phases VI and VII have a structure similar to phase V. Phase VIII polymerizes irreversibly upon compression above 25 GPa without any catalyst, producing sp(CH/F) materials. The - interaction is still dominant below 0.5 GPa but is most likely to be overstepped under further compression, which is important for discussing the supramolecular phase transition and the polymerization process.