3,7-Diazabicyclo[3.3.1]nonane-2,6-diones: building of homo- and heterochiral crystals

3,7-Dimethyl-3,7-diazabicyclo[3.3.1]nonane-2,6-dione-1,5-dicarboxylic acid derivatives: synthesis, structure and resolution

“…As we have found recently, 1 the crystalline parent dilactam 3,7-diazabicyclo[3.3.1]nonane-2,6-dione forms expected 2 homochiral H-bonded helical suprastructures, whereas its 1,5-diethoxycarbonyl derivative 1 and the other parent dilactam 3,7-diazabicyclo[3.3.0]octane-2,6-dione 3 are self-assembled in heterochiral H-bonded tapes of the diagonal zigzag type. Each link of this zigzag is cloned in infinite columns, which are alternated in the direction of the skeleton packing (Scheme 1).…”

“…It was suggested that homochiral self-assembling can be accomplished through H-bonding of the columns by modified 1,5-substituents with the elimination of the lactamic H-bonding by N-methylation (Scheme 1). In this study, we performed a search for conglomerates in the series of 3,7-dimethyl-3,7diazabicyclo[3.3.1]nonane-2,6-dione-1,5-dicarboxylic acid derivatives 1,4,5 (Scheme 2).…”

Anion–anion interactions: their nature, energy and role in crystal formation

“…Such a supramolecular motif also persists in the case of ionic systems. Thus according to the results of X-ray diffraction of tetrahydrates of potassium (acid salt), strontium, calcium, and cobalt 3,6-dioxo-2,5-diazabicyclo[2.2.2]octane-1,4-dicarboxylates (DBOD), 22 the packing of the DBOD and DBND dianions remains unchanged. In the structures of the above-mentioned salts (Fig.…”

“…The formation of such extremely stable supramolecular motifs can be the basis for the design of, for instance, liquid crystal materials using this class of compounds. 21,22 Similarly, in the crystal of the complex of macrocyclic tetraamide receptor 1 with PhCOO 7 (NBu n 4 + , the interactions between the anions lead to the formation of the supramolecular architecture, 23 which has earlier been observed only for the alkali metal complexes with crown ethers. 24 This compound is the first example of the crystal structure in which the receptor molecules are packed in such a way that the channels filled with the benzoate anions are formed.…”

“…Zigzag chains in the crystals of H-bonded dianions of a series of tetrahydrates of DBOD salts 22. M is a metal ion.…”