An international team of researchers synthesized a new type of cobalt-based metal-organic material, which can change its structure. The compound turned out to be more stable and elastic than its predecessors based on other metals. Such materials may be applicable for targeted drug delivery, as well as for filtering gases and liquids. The results are published in the Journal of Materials Chemistry A.

Some crystalline porous materials contain organic and inorganic components, for example, metal ions bound together by organic compounds, have amazing properties. Depending on the external conditions, pores in such a compound can expand or contract. Such materials are called metal organic frameworks. The size of such a polymer can reach from a tenth of a millimeter to several nanometers. To date, more than twenty thousand organometallic frameworks have been synthesized, but only a few of them have body mobility.

Due to high porosity, up to 90 percent of the volume, metal organic frameworks can contain a large number of "guest molecules", for example, drugs, gases or liquids. Therefore, they can potentially be useful in the targeted delivery of drugs, storage or purification of various gases and liquids. They can also be used as components of biosensors, gas sensors and filters for nuclear wastes.

A team of scientists from Germany, Belgium and Russia, including the researchers from the Krasnoyarsk Science Center SB RAS, investigated a new compound which is able to change its structure. Here, cobalt is used as its metal base. It turned out that the cobalt-based metal organic polymer framework has a unique property of selective absorption of other compounds. For example, in the case of a mixture of gases, it will not absorb methane and nitrogen into its pores. Another atypical property is the slower degradation of the material in air. Scientists suppose that this may be due to lower strain energy and pressure in the material.

“The results show that in the open state the properties of the cobalt-based compound with are crucially different from other metal organic frameworks with a similar structure. One of the reasons is that this structure is softer. In the future, we plan to study the influence and dependence of the properties of this compound on external factors, such as pressure, heating, and introduction of various guest molecules. This will allow us to understand the operation principle of such polymer materials and, in the future, to synthesize metal organic frameworks with predetermined properties, ”  says one of the authors of the study, Candidate of Physical and Mathematical Sciences, senior research associate of the L.V. Kirensky Institute of Physics KSC SB RAS, Alexander Krylov.