Nucleation in complex multi-component and multi-phase systems: General discussion

Sarah Price, Bart Rimez, Wenhao Sun, Baron Peters, Hugo Christenson, Colan Hughes, Changquan Calvin Sun, Stéphane Veesler, Haihua Pan, Clement Brandel, Beatrice Biscans, Hugo Meekes, Ian Rosbottom, Wieslaw J. Roth, Linda Seton, Francis Taulelle, Simon Black, Terence Threlfall, Peter Vekilov, Sendhil PoornacharyJürg Diemand, Dimitrios Toroz, Matteo Salvalaglio, Pratchaya Tipduangta, Jan Sefcik, Samuel Booth, Ake Rasmuson, Sophie Janbon, Joop Ter Horst, Elena Simone, Robert Hammond, Celso Aparecido Bertran, Thomas Vetter, Richard Sear, Jim De Yoreo, Kenneth Harris, Radoljub Ristic, Anne Kavanagh, Kevin Roberts, Eric Breynaert, Allan Myerson, Gerard Coquerel, David Wu, Helmut Cölfen, Herma Cuppen, Mireille Smets, David T. Wu

Research output: Contribution to journalComment/debatepeer-review


Kenneth Harris opened a general discussion of the paper by Herma Cuppen: It is well established from solid-state NMR and other techniques that the NH3+ group in crystalline amino acids undergoes rapid rotation about the C–NH3+ bond. Is the phase transition between the β and α phases of DL-norleucine associated with any significant discontinuity in the rate of this motion, and/or the temperature dependence of the rate of this motion? Furthermore, is there any evidence for disorder (dynamic or static) of the alkyl chain of the norleucine molecules in the α and β phases, and if so, does the nature of this disorder change significantly at the phase transition?

Herma Cuppen answered: Rotation barriers about the C–NH3+ bond depend on the motive of the hydrogen bonding network in the crystalline phases. For DL-norleucine this motive stays intact during the transition, and I therefore do not expect a large difference for the two phases. The changes occur where the aliphatic chains interact. In a previous study,1 we determined the rotation barrier of the methyl group by means of molecular dynamics simulations for both phases. We found them to be identical, and to be in agreement with experimental values for DL-norvaline2 and DL-norleucine.3 We did not find any correlation between internal movement of the molecules and the onset of the transition.
Original languageEnglish
Pages (from-to)503-542
Number of pages40
JournalFaraday Discussions
Early online date17 Jun 2015
Publication statusPublished - 1 Jul 2015


  • solid state NMR
  • phase transition
  • crystalline phases


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