Reply to comment on Couzi et al. (2018): a phenomenological model for structural phase transitions in incommensurate alkane/urea inclusion compounds.

ABSTRACT: In a recent paper (Couzi et al. 2018 R. Soc. open sci. 5, 180058. (doi:10.1098/rsos.180058)), we proposed a new phenomenological model to account for the I?II?"III" phase sequence in incommensurate n-alkane/urea inclusion compounds, which represents an alternative interpretation to that proposed in work of Toudic et al. In a Comment (Toudic et al. 2019 R. Soc. open sci. 6, 182073. (doi:10.1098/rsos.182073)), Toudic et al. have questioned our assignment of the superspace group of phase II of n-nonadecane/urea, which they have previously assigned, based on a (3 + 2)-dimensional superspace, as C222₁(00?)(10?). In this Reply, we present new results from a comprehensive synchrotron single-crystal X-ray diffraction study of n-nonadecane/urea, involving measurements as a detailed function of temperature across the I?II?"III" phase transition sequence. Our results demonstrate conclusively that "main reflections" (h, k, l, 0) with h+k odd are observed in phase II of n-nonadecane/urea (including temperatures in phase II that are just below the transition from phase I to phase II), in full support of our assignment of the (3+1)-dimensional superspace group P2₁2₁2₁(00?) to phase II. As our phenomenological model is based on phase II and phase "III" of this incommensurate material having the same (3+1)-dimensional superspace group P2₁2₁2₁(00?), it follows that the new X-ray diffraction results are in full support of our phenomenological model.

SUBMITTER: Christensen K 

PROVIDER: S-EPMC6731733 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature