Hylton, RK;
Tizzard, GJ;
Threlfall, TL;
Ellis, AL;
Coles, SJ;
Seaton, CC;
Schulze, E;
... Price, SL; + view all
(2015)
Are the crystal structures of enantiopure and racemic mandelic acids determined by kinetics or thermodynamics?
Journal of the American Chemical Society
, 137
(34)
pp. 11095-11104.
10.1021/jacs.5b05938.
Preview |
Text
jacs.5b05938.pdf Download (3MB) | Preview |
Abstract
Mandelic acids are prototypic chiral molecules where the sensitivity of crystallized forms (enantiopure/racemic compound/polymorphs) to both conditions and substituents provides a new insight into the factors that may allow chiral separation by crystallization. The determination of a significant number of single crystal structures allows the analysis of 13 enantiopure and 30 racemic crystal structures of 21 (F/Cl/Br/CH3/CH3O) substituted mandelic acid derivatives. There are some common phenyl packing motifs between some groups of racemic and enantiopure structures, although they show very different hydrogen-bonding motifs. The computed crystal energy landscape of 3-chloromandelic acid, which has at least two enantiopure and three racemic crystal polymorphs, reveals that there are many more possible structures, some of which are predicted to be thermodynamically more favorable as well as slightly denser than the known forms. Simulations of mandelic acid dimers in isolation, water, and toluene do not differentiate between racemic and enantiopure dimers and also suggest that the phenyl ring interactions play a major role in the crystallization mechanism. The observed crystallization behavior of mandelic acids does not correspond to any simple "crystal engineering rules" as there is a range of thermodynamically feasible structures with no distinction between the enantiopure and racemic forms. Nucleation and crystallization appear to be determined by the kinetics of crystal growth with a statistical bias, but the diversity of the mandelic acid crystallization behavior demonstrates that the factors that influence the kinetics of crystal nucleation and growth are not yet adequately understood.
| Type: | Article |
|---|---|
| Title: | Are the crystal structures of enantiopure and racemic mandelic acids determined by kinetics or thermodynamics? |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/jacs.5b05938 |
| Publisher version: | http://dx.doi.org/10.1021/jacs.5b05938 |
| Additional information: | This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1472682 |
Archive Staff Only
 |
View Item |
