The 10th International Conference on Molecular Electronics (ElecMol) was celebrated this year in Lyon, France. A conference to stablish up-to-date scientific exchange on recent advances in the field of molecular electronics, gathering researchers from all over the world around top-level invited speakers. This reunion is also an opportunity for the development of national and international collaborations between academic and private partners at the highest level.

ElecMol is concerned with many disciplines, and this year, 8 awards for the best poster were given across all of the topics that affect the conference. Out of those eight possible winners, two are ICMAB Researchers!

Nerea González Pato, from the Molecular Nanoscience and Organic Materials (NANOMOL) Group, won a Best Poster Award for her work on “Highly fluorescent organic radical molecules arranged into nanoparticles for nanothermometry”.

Nerea González Pato with her poster: “Highly fluorescent organic radical molecules arranged into nanoparticles for nanothermometry”.

Abstract of the study:

The tris-(2,4,6-trichlorophenyl) methyl radical (TTM) molecules present interesting optoelectronic properties. These molecules are considered as inert carbon free-radical for their high chemical and thermal stability. Its open-shell molecular electronic configuration gives place to promising optoelectronic characteristics, like emission at large wavelengths, large Stokes shift or emission lifetime of the order of ns.

Despite such interesting properties, there are some limiting factors for nanothermometry: water compatibility, low fluorescent quantum yield or low photostability. Recently, several molecular approaches have been proposed to enhance these fundamental parameters, highlighting the development of organic nanoparticles (ONPs). Nanoparticles are very promising arrangement for organic molecules, giving them higher biocompatibility and stability in water.

Here we report the preparation of organic radical NPs and their optical behavior. The NPs are made up of blends of the optically neutral tris(2,3,4,5,6-chlorophenyl)methane (TTM-αH), as a matrix, doped with the optically active TTM radical. Demonstrating that TTM radical molecules, shaped like ONPs shows a clear improvement of luminescence and photostability. These ONPs exhibit a dual fluorescence emission due to radical monomers and excimers at higher wavelenghts. While the monomer emission is almost unaltered varying temperature (internal reference), the excimer emission decrease its intensity while increasing temperature. Moreover, the intensity of these emissions can be modulated with a magnetic field (18 T at 4.2 K) and its excited-state dynamics has been measured using optically detected magnetic resonance (ODMR) corroborating the excimeric emission.

 Alejandro De Sousa and Nerea González at ElecMol 2021.

Jesús Alejandro De Sousa Rodríguez, from the Molecular Nanoscience and Organic Materials (NANOMOL) Group, won a Best Poster Award for his work on “Chiral propeller radical based SAMs”.

Jesús Alejandro De Sousa Rodríguez with his poster: “Chiral propeller radical based SAMs”.

Abstract of the study:

Chirality is a very important property of molecules and biomolecules but also nanoparticles. Pharmaceutic action, some smells and tastes, Life (ADN helix), etc, are governed by chirality. Synthetic materials properties and the devices properties derived from them can be modulate by chirality. In organic materials chirality can determine the optical behaviour, molecular recognition and conductivity. For example, it was demonstrated by Naaman et al. the action of chiral molecules in electron spin polarized transport (Chiral induce spin selectivity-CISS).

Our group has deeply studied the preparation of persistent organic radicals-based materials and, in particular those derived from the Perchlorotriphenyl methyl (PTM) radical. This radical is paramagnetic, redox active, fluorescent and also chiral. Remarkably, the circularly polarized luminescence behaviour for PTM enantiomers was recently reported. Also, Interestingly, towards practical applications in devices, PTM radical has been grafted on different surfaces (silicon, gold, ITO, HOPG) via alkyl, thiol, silane and and diazonium salt groups, respectively).

Here we present the preparation of thin-films of a PTM derivative having terminal alkyne groups able to react with gold.First, PTM radical Plus (P) and Minus (M) atropisomers were separated by HPLC and characterized by Circular Dichroism (CD) in solution. The thermodynamic barrier was determine using a chromatographic method ( ΔG=21.6kcal/mol). Although fast racemization was found in solution, stable thin films, of both enantiomers, could be prepared at low temperature. The CD response of the resulting films revealed high stability, showing the total racemization at 80ºC. Furthermore, thanks to the -C≡C-H functional groups self-assembled monolayers of both enantiomers were successfully prepared. Monolayers were characterized by XPS, cyclic voltammetry and RAMAN. Results reveals a good coverage of the surfaces, and a good stability of the grafting.

Congratulations to both on these recognitions!

More information

• Best Poster Prize for Enrique Pascual at the #HOPV20 Online Conference
• Lídia Ballell, Poster Prize at the SCN2 II Annual Conference of Nanomedicine
• Sohini Sinha, best Poster Prize at the UAB PhD in Chemistry Doctoral Workshop 2021 for her presentation on luminescent systems for imaging