cm7b01446_si_001.pdf (1.03 MB)
From Linear Molecular Chains to Extended Polycyclic Networks: Polymerization of Dicyanoacetylene
journal contribution
posted on 2017-06-26, 00:00 authored by Huiyang Gou, Li Zhu, Haw-Tyng Huang, Arani Biswas, Derek W. Keefer, Brian L. Chaloux, Clemens Prescher, Liuxiang Yang, Duck Young Kim, Matthew D. Ward, Jordan Lerach, Shengnan Wang, Artem R. Oganov, Albert Epshteyn, John V. Badding, Timothy A. StrobelDicyanoacetylene
(C4N2) is an unusual energetic
molecule with alternating triple and single bonds (think miniature,
nitrogen-capped carbyne), which represents an interesting starting
point for the transformation into extended carbon–nitrogen
solids. While pressure-induced polymerization has been documented
for a wide variety of related molecular solids, precise mechanistic
details of reaction pathways are often poorly understood and the characterization
of recovered products is typically incomplete. Here, we study the
high-pressure behavior of C4N2 and demonstrate
polymerization into a disordered carbon–nitrogen network that
is recoverable to ambient conditions. The reaction proceeds via activation
of linear molecules into buckled molecular chains, which spontaneously
assemble into a polycyclic network that lacks long-range order. The
recovered product was characterized using a variety of optical spectroscopies,
X-ray methods, and theoretical simulations and is described as a predominately
sp2 network comprising “pyrrolic” and “pyridinic”
rings with an overall tendency toward a two-dimensional structure.
This understanding offers valuable mechanistic insights into design
guidelines for next-generation carbon nitride materials with unique
structures and compositions.