The molecules, the properties of which may be easily and predictably changed by some external exposure including light, temperature and pressure, are of high demand in modern physics. Such compounds may be used for molecular switches, as well as for optic and temperature sensors. Photochromic spiropyrans belong to such type of compounds – the organic molecules consisting of several rings linked in a chain. When exposed to light, the chain may be “locked” (and then spiropyran is a colorless substance) or “unlocked”, i.e., unbent into a polyconjugate molecule. In the second case, the compounds have a dark-violet color.
If we join ions of metals to spiropyrans molecules, we can obtain substances responding to light not just by changing color, but by changing their magnetic properties. Scientists from the Chemical Physics and Medical Chemistry Research Center of RAS synthetized one of such compounds. To do that, the researchers mixed spiropyrans and iodine-containing salts of dysprosium and terbium (the metals of silver-gray and silver-white color) under an argon atmosphere (inert gas). Such conditions allowed for avoiding the humidity exposure potentially leading to destruction of complex compounds.
To study the magnetic properties of the obtained molecules, the researchers put them into a magnetic field. The experiment showed that under temperatures close to absolute zero point (from minus 272 to minus 268 degrees Celsius), the dysprosium complex is a mono-ion magnet (i.e., contains one ion of metal). It means that the complex becomes magnetized in the magnetic field, and after the field is switched-off preserves the magnetization strength for a long period of time. On top of that, the compound may be controlled by photo energy: under the green light the complex decayed, and under the ultra-violet one – recovered. Such property will be especially valuable when using the molecule in optoelectronic appliances.
“Thanks to their magnetic properties, the obtained molecules may potentially form the basis for information recording and storing devices, in which one bit of information will be stored by one molecule, and not by millions, it is now. This will help to make modern information processing and storing devices smaller”, the Russian Science Foundation is citing Dmitry Konarev, Doctor of Chemistry.
