Diffraction studies of hydrogen bonding and other intermolecular interactions in organic crystal structures

Abstract

In this work three different approaches to the study of intermolecular interactions are shown. The aim is to further the understanding of specific intermolecular interactions with a view to eventually allowing the prediction and design of crystal structures from the initial molecular building blocks: crystal engineering. All three approaches make use of crystal structural information derived from X-ray and/or neutron diffraction studies. The three approaches are: • Data base approach. Specifically, the study of occurrence of hi- and tri-furcated hydrogen bonds in the Crystallographic Structural Database, and the analysis of the frequency with which they occur and the geometric restrictions of such interactions.• Analysis of a series of compounds, where there are small changes in the molecular structure as the series progresses. The influence of these changes in the molecular structure on the crystal structure is considered. The series studied was the 4-amino- 4'-hydroxydiphenylalkanes as well as some of the corresponding 4-amino-4'- hydroxydiphenylsulphides and -alkylsulphides.• Detailed analysis of individual structures to identify the intermolecular interactions that are influencing the structure. The compounds analysed in this part were 2,4,6- m.s-(4-chlorophenoxy)-l,3,5-triazene co-crystallised with tribromobenzene, triphenylisocyanurate co-crystallised with trinitrobenzene, 4,4'-dinitrotetrapheny 1 methane, 2,3-dichloro-l,4-diethynyl-l,4-dihydroxy-napthalene and, 4,4-diphenyl- 2,5-cyclohexadienone.