Frank Würthner, head of the Chair of Organic Chemistry II and the Center for Nanosystems Chemistry at the University of Würzburg, is pursuing an ambitious goal: he wants to synthesise schwarzites, novel carbon-based nanomaterials with unique properties. In all likelihood, these materials can be used in the future as three-dimensional conductive porous carbon nanotube and graphene analogues for innovative batteries or as filter systems for gases and liquids.

Schwarzites are named after the German mathematician Hermann Schwarz, who theoretically described such three-dimensional periodic structures with a large surface and low weight as early as 1880. However, it has largely remained theoretical so far: ‘The synthesis of schwarzites composed of sp2-hybridised carbon is an enormous challenge, which is why chemists have paid little attention to these carbon materials to date,’ says Frank Würthner.

However, the chemistry professor's team might be able to succeed in this difficult synthesis. The European Research Council (ERC) also believes this to be the case: it has approved a corresponding project application and awarded Frank Würthner an ERC Advanced Grant worth 2.5 million euros. The new project is called ‘Supramolecular Approach to Schwarzite Carbon Materials’ (SCHWARZITE) and will run for five years.

What Advanced Grants Are Awarded For

The European Research Council awards Advanced Grants to outstanding scientists who are established in the research community thanks to their exceptional achievements. The prize money is used to advance innovative projects.
Frank Würthner received his first ERC Advanced Grant in 2018 for a project focused on converting solar energy into fuels such as hydrogen. His team developed catalysts that can accomplish the first, difficult step of artificial photosynthesis – splitting water into oxygen and hydrogen.

What Makes Schwarzites so Special

Schwarzites differ from other carbon structures such as nanotubes and graphene in that their electron system is delocalised in three dimensions. This should allow them to conduct electrical current with virtually no resistance.

‘They may even have topological transport properties, which would enable completely new physics,’ says Würthner. In fact, theoretical physicists have already predicted the presence of Dirac cones in some Schwarzite structures. These cones are considered a prerequisite for such properties.

A promising concept for how schwarzites could be produced was developed in Würthner's laboratory in 2022. It forms the basis for the successful application to the ERC.

The concept is based on the incorporation of heptagon units into nanographene structures otherwise composed of hexagons. These cause a saddle-shaped curvature of the polycyclic aromatic hydrocarbons, as found in schwarzites composed of hexagons and heptagons. The Würzburg laboratories have already succeeded in grouping such nanographene molecules in a perfect schwarzite-like arrangement around C60 fullerenes.

Following this approach, more extensive heptagon-containing nanographenes are now to be produced, characterised and chemically modified. The aim is to polymerise these into schwarzite-like three-dimensional pi-conjugated materials. The functional properties and applications of these novel materials will then be investigated at the Center for Nanosystems Chemistry, which received the necessary technical equipment for investigating new high-tech energy materials in a new building funded by the Free State of Bavaria in 2016.

About Frank Würthner

Frank Würthner, born in 1964, develops nanomaterials for applications in organic electronics and solar technology. At Julius-Maximilians-Universität Würzburg, he has headed the Chair of Organic Chemistry II since 2002 and the Center for Nanosystems Chemistry, which was founded in 2010. The Free State of Bavaria has been supporting his work since 2012, among other things in the research programme ‘Solar Technologies go Hybrid’ (SolTech).