Probing the Crystal Structure Landscape by Doping: 4‐Bromo, 4‐Chloro, and 4‐Methylcinnamic Acids. Issue 30 (4th July 2018)

• Record Type: Journal Article
• Authors: Chakraborty, Shaunak; Joseph, Sumy; Desiraju, Gautam R.
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 30(2018)
• Page Start: 9279
• Page End: 9283
• Publication Date: 2018-07-04
• Subjects: crystal engineering -- crystal structure landscapes -- crystal structure prediction -- doping -- solid solutions; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201801649
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Accessing the data points in the crystal structure landscape of a molecule is a challenging task, either experimentally or computationally. We have charted the crystal structure landscape of 4‐bromocinnamic acid (4BCA) experimentally and computationally: experimental doping is achieved with 4‐methylcinnamic acid (4MCA) to obtain new crystal structures; computational doping is performed with 4‐chlorocinnamic acid (4CCA) as a model system, because of the difficulties associated in parameterizing the Br atom. The landscape of 4CCA is explored experimentally in turn, also by doping it with 4MCA, and is found to bear a close resemblance to the landscape of 4BCA, justifying the ready miscibility of these two halogenated cinnamic acids to form solid solutions without any change in crystal structure. In effect, 4MCA, 4CCA and 4BCA form a commutable group of crystal structures, which may be realized experimentally or computationally, and constitute the landscape. Unlike the results obtained by Kitaigorodskii, all but two of the multiple solid solutions obtained in the methyl‐doping experiments take structures that are different from the hitherto observed crystal forms of the parent compounds. Even granted that the latter might be inherently polymorphic, this unusual observation provokes the suggestion that solid solution formation may be used to probe the crystal structure landscape. The influence of π⋅⋅⋅π interactions, weak hydrogen bonds and halogen bonds in directing the formation of these new structures is also seen. Abstract : Crystallization process : A thorough investigation of mixed crystals and solid solutions formed by almost isostructural molecules is reported. Experimental and computational crystal structures of 4‐chloro, 4‐bromo and 4‐methylcinnamic acids, and their binary and ternary solid solutions define a single landscape.