sigma-Hole and pi-Hole Synthon Mimicry in Third-Generation Crystal Engineering: Design of Elastic Crystals

Saha, Subhankar and Desiraju, R Gautam (2017) sigma-Hole and pi-Hole Synthon Mimicry in Third-Generation Crystal Engineering: Design of Elastic Crystals. In: CHEMISTRY-A EUROPEAN JOURNAL, 23 (20). pp. 4936-4943.

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Abstract

Designing elastic crystals is a difficult task and is of relevance in potential applications from materials to biology. Here, multi-step crystal engineering based on sigma-hole and -hole synthon mimicry is performed to obtain binary organic molecular crystals with a high degree of flexibility. A structural model is proposed based only on sigma-hole-oriented type-II halogen bonds with their characteristic orthogonal geometry. These sigma-hole contacts are then partly replaced by chemically and geometrically similar -hole synthons to obtain new crystals in the second step. In the final step, all the sigma-hole interactions are replaced with -hole interactions and elastic crystals of non-halogenated compounds are obtained. All the crystals obtained according to our protocols are found to be elastic. When crystals that do not conform to the desired structure type appeared, they were found to be brittle. This underlines the role of orthogonal-type interactions, whether they are of the sigma-hole or -hole type, in achieving elasticity. This is the first report in which -hole interactions are used for property engineering. This example may illustrate a new generation of crystal engineering in which a particular property is associated more with topological rather than chemical attributes, although the significance of the latter cannot be completely excluded.

Item Type:	Journal Article
Publication:	CHEMISTRY-A EUROPEAN JOURNAL
Publisher:	WILEY-V C H VERLAG GMBH, POSTFACH 101161, 69451 WEINHEIM, GERMANY
Additional Information:	Copy right for this article belongs to the WILEY-V C H VERLAG GMBH, POSTFACH 101161, 69451 WEINHEIM, GERMANY
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	20 May 2017 06:56
Last Modified:	20 May 2017 06:56
URI:	http://eprints.iisc.ac.in/id/eprint/56950

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