Issue 1, 2012

Different crystal forms of a rich hydrogen bond acceptor compound resulting from alternative C–H⋯O and orthogonal C[double bond, length as m-dash]O⋯C[double bond, length as m-dash]O molecular interaction patterns

Abstract

The racemic compound 2,4,6,8-tetracarbomethoxybicyclo[3.3.0]octa-2,6-diene-3,7-diol 3 is known to form a solvent-free crystal structure (Polymorph I) through repetition of a centrosymmetric dimeric unit that is constructed by concave face to concave face association of two shallow dish-shaped tetraester 3 molecules. Compounds employing such awkwardly shaped repeat units are known to be prone to yielding more than one crystal form. Systematic screening has now revealed a second solvent-free crystal form (Polymorph II), and also a family of essentially isostructural lattice inclusion compounds (Inclusion form I), of 3. The X-ray crystal structures of Polymorph II, and the p-xylene and cyclohexanol compounds of the inclusion crystal form, are described. The predominant weak interactions in all three crystal forms comprise C–H⋯O and orthogonal C[double bond, length as m-dash]O⋯C[double bond, length as m-dash]O attractive forces and their different arrangements are compared and contrasted.

Graphical abstract: Different crystal forms of a rich hydrogen bond acceptor compound resulting from alternative C–H⋯O and orthogonal C [[double bond, length as m-dash]] O⋯C [[double bond, length as m-dash]] O molecular interaction patterns

Supplementary files

Article information

Article type
Paper
Submitted
15 Jun 2011
Accepted
09 Sep 2011
First published
14 Oct 2011

CrystEngComm, 2012,14, 138-146

Different crystal forms of a rich hydrogen bond acceptor compound resulting from alternative C–H⋯O and orthogonal C[double bond, length as m-dash]O⋯C[double bond, length as m-dash]O molecular interaction patterns

J. Gao, M. M. Bhadbhade and R. Bishop, CrystEngComm, 2012, 14, 138 DOI: 10.1039/C1CE05728F

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