Metal-organic framework glasses
Two researchers of the Department of Inorganic Chemistry and Technology (D09) participated in the discovery of a new type of glassy materials, consisting of metal centers and organic ligands. This is the fourth type of glass beside oxide, metallic and organic glasses, and the first type that was discovered after 1960. The ability to make glassy metal-organic frameworks means that these materials with outstanding properties can also be prepared in a solid, transparent form, making them much easier to use in devices than polycrystalline powder.
In the study, a group of researchers investigated a metal-organic glass, which was prepared from crystalline material ZIF-62. This is a material in which zinc ions are interconnected by imidazolate and benzimidazolate ligands with one another, and which, according to the topological structure, resembles silicate materials and zeolites: similarly as silicon atoms of silicates are surrounded by four oxygen atoms and form Si-O-Si bonds, zinc atoms are surrounded by four (benz)imidazolate ions and form Zn-(b)Im-Zn bonds in ZIF-62. ZIF-62 has shown the greatest glass-forming ability among all materials inspected so far. This means that it has the highest Tg/Tm ratio, where Tm and Tg are the melting temperature of the crystalline ZIF-62 and the glass-to-liquid transition temperature of the glassy ZIF-62.
Dr. Andraž Krajnc and Prof. Dr. Gregor Mali collaborated with the NMR analysis of the crystalline and glassy materials, more precisely, they studied the spatial arrangement of the Im and bIm ligands in these materials. The work was described in an article published in Science Advances (AAAS).
Full article can be found here: http://advances.sciencemag.org/content/4/3/eaao6827