Crystallography in Hungary

Crystallography Research

Left: X-ray hologram of NiO taken at 17.9 keV, and right: reconstructed atomic positions in 3D (bottom). (Tegze M., Faigel G., Marchesini S., Belakhovsky M., Ulrich O. Nature, 407, 38, 2000.)

The Hungarian Academy of Sciences has many Research Institutes where crystallographic research is performed. The X-ray Laboratory of the Research Inst. for Solid State Physics and Optics (RISSPO) of the Hungarian Academy of Sciences (HAS) (www.szfki.hu) is led by G. Faigel (gf@szfki.hu). Six investigators in the group study phase retrieval methods, X-ray holography and single molecule imaging using powder and single crystal diffraction from liquid nitrogen temperature to 600 K. Significant recent results include structure determination of new fullerene compounds such as alkali-C60, cuban-C60 and C70 (G. Bortel, G. Oszlányi), atomic resolution X-ray holography (G. Faigel, M. Tegze), the introduction of the 'charge flipping' phase retrieval method (G. Oszlányi, A. Sütő) and the modeling of the Coulomb explosion of single molecules in a hard XFEL pulse (G. Faigel, Z. Jurek).

Uranium-containing multicomponent borosilicate waste glass: 30wt%(55SiO₂.10B₂O3.25Na₂O.5BaO.5ZrO₂)+30wt%UO₃ measured by neutron (red cross) and hard X-ray diffraction (blue circle): a) Structure factor, b) Total distribution function, c) U-O partial correlation function, d) Si-B-O (red-green-blue) network structure. (Fábián M., Proffen Th., Ruett U., Veress E., Sváb E. J. Phys.: Condens. Matter 22, 404206 (8pp), 2010).

The Neutron Diffraction Laboratory at the 10 MW Budapest research reactor of RISSPO in the Budapest Neutron Centre (www.bnc.hu) has eight researchers under the supervision of E. Sváb (svab@szfki.hu) and L. Pusztai (lpusztai@szfki.hu). Powder diffraction and reverse Monte Carlo computer simulation techniques are applied and developed for modeling disordered systems, such as alkali-borosilicate, chalcogenide, metallic glasses, molecular liquids, electrolyte solutions, and crystalline mixed oxides, and for internal stress investigations of bulk polycrystalline materials.

In 1928 Z. Gyulai and D. Hartly designed the first experiments to detect crystal imperfections. Gyulai observed that the tensile strength of NaCl whiskers depends on their diameters and can be nearly as high as that theoretically calculated for perfect crystals. He and I. Tarján grew synthetic quartz crystals in the early fifties. I. Tarján arranged for Hungary to join the IUCr in 1963 and was a co-author of the Laboratory Manual on Crystal Growth (1972). A pamphlet An Introduction to Crystal Physics was written by E. Hartmann (1984, 1998) for the Teaching Commission of IUCr. Currently, L. Kovács (lkovacs@szfki.hu) supervises sixteen researchers dealing with the growth and characterization of nonlinear optical crystals within the RISSPO.

Single crystal X-ray diffraction research was introduced in Szeged by I. Náray-Szabó (a student of L. Bragg, 1928-1930) in 1930. Together with K. Sasvári he solved several structures (e.g. cryolite) and with a generalization of crystal isomorphism he defined the descriptors of the 'sister structures' in 1943. In 1948 young physicists under the guidance of Sasvári started to work on various applications of X-ray diffraction at the Eötvös Loránd U. Since 1958 an X-ray laboratory (chaired by Náray-Szabó) in the Central Research Inst. of Chemistry, HAS, has studied inorganic and organic crystals, organosulfur compounds (spirosulfuranes), organo-silicon compounds (silatranes), clathrates, inclusion compounds and compounds of biological importance.

Polymorphism - intermolecular interactions - crystal architecture. The disappeared crystal form of 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose reappeared in Budapest (solid line) of the conformational dimorphs. The structure contains the shortest H&ctdots;H intermolecular interaction ever found in organic crystal structures till today. (Bombicz P., Czugler M., Tellgren R., Kálmán A., Angewandte Chemie, Int. Ed. 17, 1957, 2003.)

Beginning in the eighties, the study of polymorphic isostructurality and supramolecular chemistry became the focus of interest while the Dept. of X-ray diffraction was directed by A. Kálmán for thirty years. The reorganised X-ray diffraction laboratory in the Inst. of Structural Chemistry, Chemical Research Center, HAS (www.chemres.hu) is now under the supervision of M. Czugler (mcz@chemres.hu). The five members of the Laboratory (A. Kálmán, L. Párkányi, P. Bombicz, V. Hegedűs-Kudar and T. Holczbauer) are interested in crystal engineering, supramolecular chemistry, solid state reactions, and low resolution structures of 10-700 Âµ size crystals of organic, metal-organic, inorganic and protein structures, soft anionic system design and non-standard crystallization techniques with national and international collaborations. In the Laboratory for Powder Diffraction in the Inst. of Nanochemistry and Catalysis at HAS I. Sajó (sajo@chemres.hu) pursues structural research and phase analysis.

CH ↔ NH. An example for annular desmotropy of three pairs of seven-membered heterocycles confirmed by X-ray crystallography. Desmotropy (tautomerism in solid state) is uniquely demonstrated by three pairs of 4,1-benzodiazepines. The desmotropes are visibly distinguished by the puckering of the hetero-rings governed by the flopping (CH↔NH) hydrogen atoms. Holczbauer T., Fábián L., Csomós P., Fodor L., Kálmán A., CrystEngComm 12, 1712, 2010.

The Laboratory for Single Crystal X-ray Diffractometry established in 1995 at the U. of Debrecen, Inst. of Chemistry. (puma.unideb.hu/~xray) is directed by A. Bényei (abenyei@delfin.unideb.hu). His main research concerns organometallics, guanidine salts of water soluble phosphanes and their transition metal complexes, and polymorphism of pharmaceutical compounds. A recent discovery of racemic conglomerates stimulated research into techniques to achieve spontaneous resolution of these enantiomers. Application of Continuous Symmetry Measures in the comparison of hydrogen bonds represents a new direction of supramolecular research in Debrecen. In the field of macromolecular crystallography, T. Barna (Dept of Genetics and Molecular Biology) has been studying reductases and their complexes with environmentally important substrates, antifungal (PAF, NMR structure in the PDB: 2KCN) and human proteins. Powder diffraction and nanolayer studies are performed by M. Kis-Varga in the Inst. of Nuclear Research of HAS and routine powder diffraction measurement is done at the TEVA Pharmaceutical Works Ltd, Debrecen. Several graduate and undergraduate students including G. Paragh, Z. T. Nagy, C. Fekete and R. Elek are engaged in crystallographic studies.

In the Liquid Structure Laboratory at HAS (www.chemres.hu) T. Megyes, I. Bakó and S. Bálint study liquid structures by experimental (X-ray and neutron diffraction), molecular dynamic simulation and ab initio methods. The focus of their studies includes intermolecular interactions, hydrogen bonding, and ion solvation in pure solvents and their mixtures. Bulk solvent structures in complex solutions are compared with pure solvent structures and the changes in the orientation of solvent molecules in the first coordination shell are analyzed. Self-assembling supramolecules are another focus.

At the Thin Film Physics Laboratory, Research Inst. for Technical Physics and Materials Science, HAS (RITPMS) (www.mfa.kfki.hu), the research group of J. Lábár (labar@mfa.kfki.hu) investigates solid state reactions, ordering in crystals and thin films physics by analytical electron microscopy and quantitative electron diffraction in the TEM. Software was developed for processing electron diffraction ring patterns from polycrystalline samples and electron probe microanalysis. G. Radnóczi, head of Structural Research Dept. (RITPMS, HAS), studies thin films, surfaces, amorphous materials and crystalline C-N (alloyed by B, Si) and their structural and compositional characterization by TEM, as well as theoretical studies.

The research group of T. Ungár (ungar@ludens.elte.hu) Dept. of Materials Physics, Loránd Eötvös U. (ELTE) (metal.elte.hu/aft.elte.hu/Kezdolap_en.html) uses EXAFS and small angle scattering high resolution X-ray diffractometry and peak-profile analysis, to study dislocation structures and densities, microdiffraction, microstructure particle size determination, stored energy from dislocation density, crystallite size and size distribution. Current emphasis is upon the structure of metals and alloys, the dislocation model of strain anisotropy, and scanning microdiffraction to determine local variation of stored energy in heterogeneous microstructures. T. Weiszburg (weiszburg@ludens.elte.hu), I. Dódony and G. Lovas of the Dept. of Mineralogy, Centre of Geology and Environmental Physics (ELTE) (teo.elte.hu/fs/geoldirect.html) conduct investigations of natural and environmental solid materials, TOT-Fe layer silicates, archeometry, mineral topography, and the history of mineralogy.

Inhibitor molecule (shown in magenta with molecular surface) bound at the active site of prolyl oligopeptidase.

The Protein Crystallography Laboratory at ELTE was founded by G. Náray-Szabó and Z. Böcskei in 1993 with the acquisition of a diffractometer suitable for the biochemical and molecular biological research of many groups in Hungary including scientists in the Dept. of Biochemistry at LEU, the Inst. of Enzymology, and the Agricultural Biotechnology Centre where graduate and PhD students are trained in the field of protein crystallography. In 2006 the Laboratory joined the Laboratory of Structural Chemistry and Biology to study the structure, dynamics and interactions of proteins and peptides (www.chem.elte.hu/departments/protnmr). Targets for study have included metal preference, mechanism of action and substrate specificity of tryspin, chymotrypsin and prolyl oligopeptidase, the prototype of a new protease family, enzyme mechanisms and substrate specificity. Studies on proteases of the complement cascade system, an important element of innate immunity, have produced detailed models of their autoactivation mechanism, the first enzymatic event of the complement, and protein/protein interactions. C1-inhibitor, the natural inhibitor of these enzymes is of pharmacological interest. Its crystal structure shed light on the structural basis of the anti-inflammatory effect of heparin, which influences C1-inhibitor-protease complexes. In contrast to the conservative substrate hosting of the studied proteases, the prototype calcium sensor protein calmodulin showed protein/ligand interactions of a highly adaptive and promiscuous nature in its complexes with small molecular drugs and drug candidates explaining their different effects on calmodulin function. dUTPases have essential role in preventive DNA repair via exclusion of uracil and contribution of dTTP biosynthesis. Structures of dUTPase mutants and variants from different species help elucidate the role of conserved amino acid residues that could provide the basis of designing selective inhibitors.

National Organization

The chair of the National Committee of the IUCr in Hungary is G. Faigel. Past-Chair is A. Kálmán, Secretary is P. Bombicz. Members: A. Bényei, L. Kovács, L. Kőszegi, J. Lábár, G. Náray-Szabó, G. Radnóczi, I. Sajó, K. Simon, E. Sváb, T. Ungár and T. Weiszburg. The Hungarian Synchrotron Committee organizes meetings and workshops connected to X-ray crystallography. Both of these committees work under the auspices of the Physical Section of the HAS.

Facilities

The Inst. for Solid State Physics and Optics of the Hungarian Academy of Sciences has three traditional X-ray generators, a Huber-goniometer-based home made single crystal diffractometer with an Oxford cryomodule, a Huber 670 image plate Guinier camera, home made X-ray holography setup, a two-axis powder neutron diffractometer equipped with linear position sensitive detector system and a 4-circle neutron diffractometer. The Inst. of Structural Chemistry, Chemical Research Center, HAS, has a Rigaku R-AXIS RAPID image plate diffractometer, an X-Stream 2000 low temp unit, Enraf-Nonius turbo CAD-4 diffractometer, stereo microscopes, a Philips X'Pert diffractometer, a Philips PW1050 diffractometer, Philips PW1050 diffractometer equipped with an Anton Paar HTK 1200 high temperature chamber and a compact Kratky-type small angle camera, and is the Hungarian Affiliated Centre of the Cambridge Structural Database. The Laboratory for Single Crystal X-ray Diffractometry, Institute of Chemistry, U. of Debrecen has an Enraf-Nonius MACH3 CAD-4 diffractometer. The LEU has a Rigaku R-AXIS IV++ image plate diffractometer, an Oxford Cryosystems Cryostream 700 low temperature unit and a Cyberlab C-200 crystallization robot.

Awards and Current Appointments

The 2nd and the 22nd European Crystallographic Meetings were held in Hungary, in Keszthely in 1974 and Budapest in 2004. Other Crystallography-related conferences held in Hungary include the 20th General Meeting of the International Mineralogical Association (2010), the 5th Mid-European Clay Conference (2010), Conference on Reverse Monte Carlo Modelling (2003, 2006, 2009), Symmetry Festival (2009), Electron Crystallography: INNOVATIAL Process Diffraction School (2008), Ultra-high Pressure Metamorphism, the 5th EMU School & Symposium (2003), Energy Modelling in Minerals, the 4th EMU School in Mineralogy (2002), EPDIC (1998), 2nd Regional Workshop of EMAS (1996).

There is significant activity in the field of crystallography in the pharmaceutical companies Gedeon Richter, EGIS and Sanofi-Aventis (Chinoin). These industrial labs use mainly powder X-ray diffraction for analytical purposes. EGIS pharma company lately installed an R-Axis SPIDER for single crystal diffraction studies.

Electron Diffraction Research

Results from the electron diffraction study of chromium dichloride of complex vapor composition. Its structure illustrates all vibronic interactions: the monomeric molecule exhibits the Renner-Teller effect, its dimer the pseudo-Jahn-Teller effect, and its crystals the Jahn-Teller effect. The oligomers as well as the crystal display antiferromagnetic coupling.

A strong research group for molecular structure studies has developed since 1965 at the Hungarian Academy of Sciences - currently located at the Budapest Univ. of Technology and Economics under the name Materials Structure and Modeling Research Group. Its leading scientists are Istvan Hargittai (istvan.hargittai@gmail.com) and Magdolna Hargittai (hargittaim@mail.bme.hu). The group's main experimental technique has been gas-phase electron diffraction together with mass spectrometry. Their experimental data have been augmented by various spectroscopic information, and, increasingly, by quantum chemical calculations. The group focuses on the structural variations and modeling of free molecules, and has often performed joint work and comparisons with crystallographic studies.

Currently, one of their main interests is in structural peculiarities in metal halides under the leadership of Magdolna Hargittai. They have been involved with determining rare structural effects due to vibronic (vibrational-electronic) interactions - the Jahn-Teller, Renner-Teller, and pseudo-Jahn-Teller effects - and relativistic effects. They discovered several unexpected structural features, such as the effect of spin-orbit coupling and of the 4f orbital occupation on molecular geometry and found examples of antiferromagnetic coupling and spin-crossover in gas-phase metal halide structures combining data from a plethora of techniques. Lately they have also been involved with determining the structural relationship between the gas-phase and crystal-phase structures of metal halides.

The group, under the leadership of its founder Istvan Hargittai, has been involved in a number of international collaborations that have increased the accuracy of gas-phase electron diffraction studies and have expanded the field to include unstable species. The broad scope of their work can be seen in their publications in a wide spectrum of journals. They have also published several monographs including: their books on gas-phase electron diffraction (I. Hargittai, M. Hargittai, eds., Stereochemical Applications of Gas-Phase Electron Diffraction, Parts A and B, VCH Publishers: New York, 1988); symmetry (M. Hargittai, I. Hargittai, Symmetry through the Eyes of a Chemist. Third Edition. Springer, 2009; 2010; M. Hargittai, I. Hargittai, Visual Symmetry. World Scientific, 2009); molecular structures (A. Domenicano, I. Hargittai, eds., Accurate Molecular Structures. Oxford University Press, 1992; R. J. Gillespie, I. Hargittai, The VSEPR Model of Molecular Geometry. Dover (reprint edition), 2011); and leading personalities in crystallography (I. Hargittai, M. Hargittai, B. Hargittai, Candid Science I-VI. Imperial College Press, London, 2000-2006; and I. Hargittai, The DNA Doctor. World Scientific, 2007).

Istvan Hargittai is the Editor-in-Chief of Structural Chemistry (Springer-Verlag), an international journal in its 22nd year of publication.

Find further information on the research groups at www.amkcs.ch.bme.hu.