Chirality in Crystal Engineering

Doctoral thesis, 2003

Crystal engineering combines supramolecular chemistry with solid state chemistry. The goal is to make molecular entities assemble into predefined structures with specific properties. At the same time much research is focused on the understanding of the intermolecular interactions governing the crystallisation process. The main part of the work was focused on three connected nets and how they can be assembled. Special attention will be given to chirality as a part of the design and to the constructive and disruptive parts played by weak interactions such as hydrogen bonding. Both theoretical and experimental work was carried out and all compounds were characterised by single crystal X-ray diffraction. Two types of building blocks were used in the experimental work: octahedral [M(L)3] complexes, (M=Co, Cr, L=biim= 2,2'-biimidazole, oxalate) and diazadiindole. It is shown that the chirality of the starting materials has a large impact on the final structures of the 3D nets of (+)-[Co(Hbiim)3]·0.5H2O·0.8DMF, [Cr(biim)3]SO4 and [Co(biim)3]·terephthalate and the helices of optically pure [Co(Hbiim)3] solvates. The importance of chirality in the assembly of the 1-D chains of Ba[Cr(ox)2phen] as well for the magnetic and structural properties of [Cr(en)(ox)2][Cr(en)(ox)2]·2H2O, Δ-[Cr(en)3]Δ-[Cr(ox)3], and Δ-[Co(en)3]Δ-[Cr(ox)3] was also demonstrated. The second type, diazadiindole, is a chiral organic cleft-type molecule and structural investigations of aggregates of both the racemic and optically pure form were carried out. Both are assembled into chains with solvent molecules as a part of the chains.