Phase transitions and polymerization of C
H
-C
F
cocrystal under extreme conditions
Wang, Y.*; Wang, L.*; Zheng, H.*; Li, K.*; Andrzejewski, M.*; Hattori, Takanori
; Sano, Asami
; Katrusiak, A.*; Meng, Y.*; Liao, F.*; Hong, F.*; Mao, H.-K.*
Pressure-induced polymerization (PIP) of aromatic molecules can generate saturated carbon nanostructures. As a strongly interacted
-
stacking unit, the C
H
-C
F
adduct is widely applied in supramolecular chemistry, and it provides a good preorganization for the PIP. Here we investigated the structural variation of C
H
-C
F
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.