Small molecule crystallography

In collaboration with research groups in the fields of organic and organometallic chemistry we carry out crystallographic studies of various compounds. (CCDC reference codes: 1525622, 1525638, 1525646, 1825313, 1890659, 1890661, 1990174, 244367, 244368, 244369, 244370, 1525638, 1525622, 1525646).

Configuration of chirality centers, as well as ring conformation and puckering of amine nitrogens of a novel partly saturated beta-carboline was confirmed by the crystal structure of its solvate with DMSO. Both DMSO molecules are disordered in the structure with preferred orientation more favorable for hydrogen bonding (Collaboration: Prof. Csámpai ‘s group Institute of Chemistry, Eötvös Loránd University).

Configuration was confirmed for two 1,3-diazaspiro[bicyclo[3.1.0]hexane]oxindole derivatives synthetized in one-pot reaction of isatins, α-amino acids and 2H-azirines. The partial merohedral twinning of the compound was rationalized by the formation of pseudo-symmetric linear associates of the molecules within the crystal structure, which are connected in a cog-like superstructure. (Collaboration: AVIDIN Ltd., Department of Organic Chemistry, University of Szeged).

We are involved in a structural study on calcium D-isosaccharinate and calcium D-gluconate, two main products decomposition of cellulose in alkaline environments (coordination polymers). Unusually, the calcium coordination number is nine for calcium-gluconate, while it is eight for calcium isosaccharinate as now established (Collaboration: Crystallography Laboratory, Biological Research Center, HAS; Departments of Organic and Inorganic and Analytical Chemistry, University of Szeged;University of Sydney).

The structure of the antiproliferative compound 4,5-dihydrobenzoferroceno[1,2-d][1,2,3]selenadiazole contains four crystallographically independent molecules. A small tilt of one of the molecules cause C2/c -like pseudo-symmetry and perfect pseudo-merohedral twinning. (Collaboration: research groups of Prof. Pasinszki and Prof. Csámpai, Institute of Chemistry, Eötvös Loránd University).

The comparative alcoholysis study of N-silylated heterocyclic carboxamides (lactams, imides, ureas) was carried out along with QM calculations and crystallographic analysis aiming to explore the relationship between the molecular structure and the respective silyl transfer ability. The structural constraints imposed on the accessibility of the carbonyl oxygen for the silicon center play a decisive role in the ease of desilylation. The new model proved to be useful to predict the relative rates of silyl transfer reactions for a wider range of substrates. (Collaboration: Dr. Szalay Department of Inorganic Chemistry, Institute of Chemistry, Eötvös Loránd University). In the crystal structures of N-trimethylsilylated cyclic ureas, the bond lengths and angles around the Si atom vary significantly, supporting that the silylating power depends on the pseudo-pentacoordinate character of the tetracoordinate silicon. A simple structure-based number measuring the pseudo-pentacoordinate character of the silicon can be used for predicting reactivity.