#weekendusers Supermolecules, former colleagues’ reunion and sleepless nights

28-08-2017

An international team made up by Russian and Italian scientists is studying porphyrin nanostructures, which can lead to the so-called supermolecules.

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Porphyrin nanostructures can present an energy transfer between adjacent molecules, which is strongly affected by the structure of the ensemble. This makes them promising for the conversion of solar energy into chemical or electrical energy in, for example, photocatalytic applications, sensors, organic light emitting diodes and organic photovoltaics.

Larissa Mayorova, main proposer of the experiment and professor at Ivanovo State University of Chemistry and Technology in Russia, explains that their goal is to study how magnesium porphine – the structural basis of chlorophyll (MgPor) - stacks up on a water surface and creates a particular type of molecular system – supermolecular assemblies with strong noncovalent intermolecular interactions and with functional properties extrinsic to the constituent molecules. These assemblies function like one supermolecule. Previously, the team discovered, while studying formation of two-dimensional porphyrin nanostructures at the water surface, and partially by chance, that MgPor molecules stack themselves when they are slowly pushed together. The attraction between molecules in the ensemble is so strong that no solvent can separate them. On top of that, the solution of the supermolecules is transparent in visible light and absorbs the ultraviolet and near-infrared, in contrast with the pink tinge of the solution of MgPor. “When we discovered this we thought it could potentially be very interesting from both fundamental and application points of view ”, explains Mayorova.

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The team, from left to right, top row: Oleg Konovalov, Larissa Mayorova, Svetlana Erokhina. Front row: Michela Pisani and Nadezhda Kharitonova. Missing from the picture: Viktor Erokhin, who had been working overnight.

Mayorova was in contact with Viktor Erokhin, a former colleague from her PhD days in the Shubnikov Institute of Crystallography of the Russian Academy of Science in Moscow. Erokhin was himself still in touch with Oleg Konovalov, beamline responsible on ID10 and also colleague from the time in the Institute of Crystallography. Erokhin realised that the X-ray facility available on ID10 could be very beneficial for Mayorova’s research and suggested that she apply for beamtime. Erokhin explains that “thanks to the technical facilities and expertise of the beamline responsible and staff members, ID10 is the best synchrotron beamline in the world for studies to such systems”. Fast forward several months, and after the proposal had been accepted, Mayorova, together  with her masters student from the Ivanovo State University of Chemistry and Technology in Russia and collaborators from Kazan Federal University (Russia), Marche Polytechnic University (Italy) and National Council of Researches (Parma, Italy), started the intensive experimental session.

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The set-up on ID10.

The solution before and after the experiment.

“It is great to be here, and this is possible thanks to the fact that Russia is a member of the ESRF”, she says. “The experiment is going really well so far”, she adds. “I love France since my post doctoral time at University Paris-V, Laboratory of physics and biophysics (Paris). And it has been fun to be reunited in Grenoble with old friends after such a long time”.

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The team with Victor Erokhin (left) and Nadezhda Kharitonova injecting the solution on the layer of water (right). 

Text by Montserrat Capellas Espuny. Photos by María Sánchez Durán.

Top image: The scientists inject the solution onto a layer of water. Credits: María Sánchez.