Guanidinium salts in the spotlight

Normal salts are well behaved and have uniform action (i.e. in the one direction)  of the collapse-swelling equilibrium. So the more salt we add, the stronger the effect. However, guanidinium thiocyanate (GndSCN) is special and collapses the polymer at first dose, but but reswells the the polymer at higher salt concentrations.Addition-of-salt-and-LCST-2

Our story, which was recently published in JACS was presented at Spring-Meeting of DPG in Dresden 2017 – pdf with presentation.


Colorful effects of guanidinium salts on biomolecules make it to JACS

Already pure guanidinum chloride (GndCl) solution is remarkable. It contains a significant fraction of guanidinium cations in direct contact, a typically rare feature, which is counterintuitive (on electrostatic grounds) link.gndx_toc_jacs

Proteins are unfolded and solutes destabilized in concentrated solutions of GndCl in general. Indeed GndCl is, after urea, the second most common denaturing agent. In the recent article we present different faces of guanidinium action, stabilizing as well as destabilizing which are intimately connected with the anion in action. This work is a joint experimental (spectroscopy & thermodynamics) computational (simulations & theory) study. link

Danubius Young Scientist Award for Jan Heyda

The award seeks to encourage young scientists to engage themselves in the scientific examination of the multifaceted issues and questions specifically related to the Danube and to stimulate the specific community in the Danube Region. Universities, Academies of Scincences and research Institutions in all 14 countries of the Danube Region have been encouraged to nominate suitable and promising candidates that have been assessed by an international expert jury. The highest ranked candidate of each of the countries that submitted eligible nominations was awarded with the prize. (Krems 9/11/2016)

More details are available via this link.

Lower critical solution temperature of an ionic liquid and its control by supramolecular host–guest interactions

The LCST is not restricted to macromolecular systems only, but can be found even in binary mixtures, although rarely. In this work our colleagues found and  ionic-liquid, which has LCST (~45°C) , when mixed with acetone. It was found, that LCST is not present in any of other 10  organic solvents tested, and also not when anion of ionic liquid is modified. Moreover the LCST is very sensitive to the addition of supramolecular hosts, such as pillar[5]arene or crown ether, which decrease/or/increase the LCST by ~10°C, when present already below 100mM concentration.

The article is open-access thanks to the donation of the library FU Berlin. link