Document Type

Article

Publication Date

11-2016

Keywords

molecular hydrates, CSD survey, hydrate screening experiments, electrostatic potential, hydrogen bonding, N-heterocyclic aromatic compounds

Digital Object Identifier (DOI)

https://doi.org/10.1107/S2052252516015633

Abstract

Hydrates are technologically important and ubiquitous yet they remain a poorly understood and understudied class of molecular crystals. In this work, we attempt to rationalize propensity towards hydrate formation through crystallization studies of molecules that lack strong hydrogen-bond donor groups. A Cambridge Structural Database (CSD) survey indicates that the statistical occurrence of hydrates in 124 molecules that contain five- and six-membered N-heterocyclic aromatic moieties is 18.5%. However, hydrate screening experiments on a library of 11 N-heterocyclic aromatic compounds with at least two acceptor moieties and no competing hydrogen-bond donors or acceptors reveals that over 70% of this group form hydrates, suggesting that extrapolation from CSD statistics might, at least in some cases, be deceiving. Slurrying in water and exposure to humidity were found to be the most effective discovery methods. Electrostatic potential maps and/or analysis of the crystal packing in anhydrate structures was used to rationalize why certain molecules did not readily form hydrates.

Comments

CCDC references: 1508120; 1509584; 1509585; 1509586; 1509587; 1509588; 1509589; 1509590

Rights Information

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

IUCrJ, v. 3, no. 6, p. 430-439

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