Crystallography in Macedonia

The Republic of Macedonia is a small country (~25 700 km²) located in the central Balkan peninsula in South-Eastern Europe, with a population of about 2 million. The first X-ray scattering measurements reported by a Macedonian researcher were those of S. Pocev of the Faculty of Technology and Metallurgy (SS. Cyril and Methodius U.) in Skopje, who worked with G. Johansson at the Royal Inst. of Technology in Stockholm, Sweden. Pocev published the paper An X-ray Investigation of the Coordination and the Hydrolysis of the Uranium(IV) Ion in Aqueous Perchlorate Solutions in Acta Chemica Scandinavica in 1973. Later, he completed his PhD thesis on structures of mercurated oxonium and sulphonium salts at the U. of Zagreb (1978), and the results were published in the Journal of the Chemical Society.

The crystal structure of tetrakis(trifluoroacetoxymercury)methane (J. Chem. Soc. Chem. Comm. 546 (1974), 646-647).

From 1972 through 1974, G. Jovanovski from the Inst. of Chemistry (Faculty of Natural Sciences and Mathematics, FNSM) in Skopje was a student in the X-ray Laboratory of D. Grdenić and B. Kamenar at the U. of Zagreb, where he determined the crystal structure of tetrakis(trifluoroacetoxymercury)methane, the first example of a carbon atom bound to four mercury atoms. Later, Jovanovski determined crystal structures of metal saccharinate complexes for his PhD thesis at the same University. With J. Thomas (Uppsala U.), he studied the deformation electron density of potassium oxalate monohydrate.

Returning to Skopje in the 1980s, Jovanovski introduced a course in crystallography at the SS. Cyril and Methodius U. in Skopje as a part of the Structure of Molecules major, in the Dept. of Chemistry at FNSM. At that time, two powder diffractometers were available in Macedonia - a JEOL instrument at FNSM, and a Philips instrument operated by the Faculty of Technology and Metallurgy. The instruments were used for routine analyses, characterization, simple experiments and teaching. In the following years, a small group of crystallography researchers was established at the Inst. of Chemistry, including A. Mirčeva, O. Grupče, P. Naumov and P. Makreski. Sporadically, X-ray diffraction was employed for structure determination and characterization by other members of the Inst. of Chem.: B. Šoptrajanov, V. Jordanovska, V. Petruševski, S. Aleksovska, V. Stefov, Gj. Petruševski and T. Runčevski.

From left to right: Petre Makreski, Gjorgi Petruševski, Gligor Jovanovski, Panče Naumov and Tomče Runčevski.

When the country was part of SFR Yugoslavia, Jovanovski attended the annual meetings of the Yugoslav Centre of Crystallography and organized the 1981 meeting in Skopje. Since 1996, Jovanovski has participated in the annual Croatian-Slovenian crystallographic meetings, together with other Macedonian crystallographers (S. Pocev, V. Jordanovska, A. Mirčeva, O. Grupče, P. Naumov and P. Makreski). Recently, a Division of Crystallography was established as part of the Society of Chemists and Technologists of Macedonia.

Genuine crystals of the mineral lorandite (TlAsS₂) from Alšar, Macedonia.

None of the national or private universities in Macedonia has modern crystallographic equipment. Active Macedonian crystallographers have conducted research in foreign universities, or in collaboration with such institutions. P. Naumov and P. Makreski, who were mentored by Jovanovski, are currently active in the field. The main studies underway in Macedonia concern chemical crystallography (especially metal-coordination compounds as models for biological effects of food additives), inorganic compounds (spectra-structural correlations in isomorphous and isotypic series), organic compounds with interesting electronic and optical properties, solid-state reactivity (photochromism and thermochromism), and polymorphism of pharmaceuticals. An Atlas of Minerals from the Republic of Macedonia is to be published soon (in English) by the Macedonian Academy of Sciences and Arts.

Crystals of the genuine Macedonian mineral realgar (As₄S₄) before exposure to visible light (a) and after photochemical conversion to pararealgar (b) (J. Am. Chem. Soc. 132 (2010), 11398-11401). Copyright: American Chemical Society.

One of the most active research groups of the Division of Crystallography in Skopje (G. Jovanovski, O. Grupče and P. Naumov) has over 40 publications in international journals, which are mainly related to the coordination chemistry of saccharin (an artificial sweetener with suspected carcinogenic activity), thiosaccharin and their mixed complexes with aromatic bases. In 2004 P. Naumov earned a PhD degree in diffraction at the Tokyo Inst. of Technology, under the supervision of Y. Ohashi. He established a laboratory for the study of photoinduced phenomena and solid-state chemistry at the National Inst. for Materials Science in Japan (2004-2007), and now leads a research group at Osaka U. (Japan). In 2009 Naumov was appointed associate professor of the Inst. of Chemistry in Skopje, where he has been spearheading the development of collaborative crystallographic research in Macedonia. The current interests of the group are materials exhibiting photoinduced and thermal phase transitions for (opto)spintronics applications, X-ray photodiffraction and time-resolved diffraction using synchrotron X-rays.

Sodium saccharinate, NaC₇H₄NO₃S.xH₂O, listed in most catalogues as a dihydrate (x = 2), has been extensively used as a food additive and has constituted the basic component of the diabetic's diet for about 125 years. This crystal structure, with Z′ = 16 and a very large unit cell, represents one of the most difficult cases for a small molecular species such as the saccharinate ion. The composition is best described as Na₆₄(C₇H₄NO₃S)₆₄.120H₂O (Angew. Chem. Int. Ed. 44 (2005), 1251-1254).

Macedonian crystallographers P. Naumov and G. Jovanovski, together with B. Kaitner (Zagreb), D. A. Rae (Canberra) and S. W. Ng (Kuala Lumpur), determined the crystal structure of the sweetener sodium saccharinate, Na₆₄(C₇H₄NO₃S)₆₄.120H₂O, a commercial compound incorrectly assumed to have been a dihydrate. This extremely complicated modulated structure with a unit cell of 15.6 nm³ and Z′ = 16 (Z = 64) was ranked #6 in the world's database of small-molecule structures with high Z′ (U. of Durham). The Macedonia research team has also described the first direct observation of an all-solid autocatalytic reaction set, a group of photo-triggered reactions proceeding in the crystals of the natural mineral realgar (J. Am. Chem. Soc. 132 (2010), 11398-11401). Ways and means of upgrading crystallographic instruments in Macedonia are being sought, and the advice and assistance of the international community would be greatly appreciated.