Abstract
A new polymorph of l-tryptophan was prepared through crystallization from the gas phase, with structure determination carried out directly from powder XRD data augmented by periodic DFT-D calculations. The new polymorph (denoted beta) and the previously reported polymorph (denoted alpha) are both based on alternating hydrophilic and hydrophobic layers, but with substantially different hydrogen-bonding arrangements. The beta polymorph exhibits the energetically favourable l2-l2 hydrogen-bonding arrangement, which is unprecedented for amino acids with aromatic side chains. The specific molecular conformations adopted in the beta polymorph facilitate this hydrogen-bonding scheme while avoiding steric conflict of the side chains.
| Original language | English |
|---|---|
| Pages (from-to) | 18788-18792 |
| Number of pages | 6 |
| Journal | Angewandte Chemie - International Edition |
| Volume | 58 |
| Issue number | 52 |
| Early online date | 17 Oct 2019 |
| DOIs | |
| Publication status | Published - 8 Nov 2019 |
Funding
In memory of Joel Bernstein (1941–2019) We thank Cardiff University (PhD studentship to O.A.R.) and the Council for At‐Risk Academics (Fellowship to O.A.R.) for support. We are grateful to Diamond Light Source for beam‐time on powder XRD beamline I11, the U. K. High‐Field Solid‐State NMR Facility for spectrometer time, and the U. K. High‐performance computing “Materials Chemistry Consortium” (EP/R029431) and Supercomputing Wales for access to computational facilities. We thank Prof. Chris Pickard and Prof. Martyn Guest for help and advice concerning DFT calculations.
All Science Journal Classification (ASJC) codes
- Catalysis
- General Chemistry