title: Pressure-induced phase transition in hydrogen-bonded supramolecular adduct formed by cyanuric acid and melamine.
abstract: Single-crystal samples of the 1:1 adduct between cyanuric acid and melamine (CA.M), an outstanding case of noncovalent synthesis, have been studied by Raman spectroscopy and synchrotron X-ray diffraction in a diamond anvil cell up to pressures of 15 GPa. The abrupt changes in Raman spectra around 4.4 GPa have provided convincing evidence for pressure-induced structural phase transition. This phase transition was confirmed by angle dispersive X-ray diffraction (ADXRD) experiments to be a space group change from C2/m to its subgroup P2(1)/m. On release of pressure, the observed transition was irreversible, and the new high-pressure phase was fully preserved at ambient conditions. We propose that this phase transition was due to supramolecular rearrangements brought about by changes in the hydrogen bonding networks.
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, PR China.
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.forename: Defang
authors.initials: D
authors.lastname: Duan
authors.forename: Run
authors.initials: R
authors.lastname: Wang
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.forename: Lingyun
authors.initials: L
authors.lastname: Tang
authors.forename: Tian
authors.initials: T
authors.lastname: Cui
authors.forename: Bingbing
authors.initials: B
authors.lastname: Liu
authors.forename: Qiliang
authors.initials: Q
authors.lastname: Cui
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Bo
authors.initials: B
authors.lastname: Zou
authors.forename: Guangtian
authors.initials: G
authors.lastname: Zou