Stabilization of molecular hydrogen-bonded chains by carbon nanotubes

We study numerically nonlinear dynamics of several types of molecular systems composed of hydrogen-bonded chains placed inside carbon nanotubes with open edges. We demonstrate that carbon nanotubes provide a stabilization mechanism for quasi-one-dimensional molecular chains via the formation of their secondary structures. In particular, a polypeptide chain (Gly)$_N$ placed inside a carbon nanotube can form of a stable helical chain ($3_{10}$, $\alpha$, $\pi$ and $\beta$-helix) with parallel chains of hydrogen-bonded peptide groups. A chain of hydrogen fluoride molecules can form hydrogen-bonded zigzag chain. We reveal that in such geometries the hydrogen-bonded chains may remain stable even at $T=500$~K. Thus, our results suggest that the use of carbon nanotubes with encapsulated hydrogen fluoride molecules may support high proton conductivity operating at high temperatures.