Tuning Proton Disorder in 3,5-Dinitrobenzoic Acid Dimers: the Effect of Local Environment

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• 作者：Andrew O. F. Jones ; Nicholas Blagden ; Garry J. McIntyre ; Andrew Parkin ; Colin C. Seaton ; Lynne H. Thomas ; Chick C. Wilson
• 刊名：Crystal Growth & Design
• 出版年：2013
• 出版时间：February 6, 2013
• 年：2013
• 卷：13
• 期：2
• 页码：497-509
• 全文大小：638K
• 年卷期：v.13,no.2(February 6, 2013)
• ISSN：1528-7505

文摘

The carboxylic acid dimer is a frequently observed intermolecular association used in crystal engineering and design, which can show proton disorder across its hydrogen bonds. Proton disorder in benzoic acid dimers is a dynamic, temperature-dependent process whose reported occurrence is still relatively rare. A combination of variable temperature X-ray and neutron diffraction has been applied to demonstrate the effect of local crystalline environment on both the degree and onset of proton disorder in 3,5-dinitrobenzoic acid dimers. Dimers which have significantly asymmetric local intermolecular interactions are found to have a higher onset temperature for occupation of a second hydrogen atom site to be observed, indicating a greater energy asymmetry between the two configurations. Direct visualization of the electron density of hydrogen atoms within these dimers using high resolution X-ray diffraction data to characterize this disorder is shown to provide remarkably good agreement with that derived from neutron data.