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The effective volumes of waters of crystallization: general organic solids
Author(s) -
Glasser Leslie
Publication year - 2020
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520620008719
Subject(s) - hydrate , crystallization , molecule , water of crystallization , clathrate hydrate , volume (thermodynamics) , organic molecules , chemistry , thermal expansion , thermodynamics , outlier , crystallography , organic chemistry , physics , mathematics , statistics
Using a list of compatible hydrate/anhydrate pairs prepared by van de Streek and Motherwell [ CrystEngComm (2007), 9 , 55–64], we have examined the effective volume per water of crystallization for 179 pairs of organic solids using current data from the Cambridge Crystallographic Structural Database (CSD). The effective volume is the difference per water molecule between the asymmetric unit volumes of the hydrate and parent anhydrate, and has the mean value 24 Å 3 . The conformational changes in the reference molecule between the hydrate and its anhydrate are shown in two figures: one for a relatively rigid standard organic molecule and (in the supplementary file) one for a more flexible linear molecule. Using data from Nyman and Day [ Phys. Chem. Chem. Phys. (2016), 18 , 31132–31143], we have also established a generic volumetric coefficient of thermal expansion of organic solids with a value of 147 ± 56 × 10 −6 K −1 . There is a significant number of outliers to the data, negative, near zero, and large and positive. Some explanation for the existence of these outliers is attempted.