Lords of the molecular Rings: An Innovative Shortcut to High-Performance Organic Materials

APCs are small, perfectly shaped molecular rings made up of repeating units linked in an endless loop. These macrocyclic organic compounds have a unique structure that makes them valuable basic building blocks for innovative technologies such as optoelectronic applications, which include displays for example. For years, the synthesis of APCs has been a tedious process requiring several steps under difficult conditions. A team of researchers at the Institute of Organic Chemistry at the University of Vienna has taken on the challenge to simplify it – with remarkable success.

The newly developed CTM method uses the "Pd-catalysed Buchwald-Hartwig cross-coupling reaction", which helps to form carbon-nitrogen bonds to create π-conjugated cyclic structures. "π-conjugated" refers to a system of alternating single and double bonds that allows the free movement of electrons, enhancing the electronic properties of the material. The CTM method provides a direct and efficient route, making the production of APCs much easier. "With this approach, we can create structurally precise APCs in a short time, under mild conditions and with high yields, making them much more accessible for both research and industrial applications," says first author Josue Ayuso-Carrillo from the University of Vienna. The method is flexible, allowing the preparation of APCs with different ring sizes (typically 4-9 members) and functional groups. It can also be carried out under typical concentration conditions (35-350 mM), making it scalable and reproducible, unlike established macrocyclization protocols requiring a highly diluted medium.

APCs produced by this method have great potential in materials such as organic semiconductors and solar technology. Thanks to their π-conjugated structures, which allow efficient electron movement, APCs can be used in various fields. In organic electronics, they can improve the efficiency and flexibility of displays, solar cells and transistors. Organic electronics contain – as the name suggests – organic material, this goes for flexible solar cells for example. Compared to typical flat panels of solar cells made of energy-intensive processed silicon, organic solar cells are lightweight, and hence can be used off-grid in unconventional surfaces. APCs‘ properties also improve light-harvesting systems, leading to better solutions for solar energy conversion and storage. In supramolecular chemistry, APCs can also be used to create advanced molecular recognition systems, sensors and catalysts. "The CTM method is not only a breakthrough in synthesis, but also a stepping stone towards the large-scale production of tailor-made materials," explains Davide Bonifazi from the University of Vienna, senior author of the study. "By eliminating unnecessary complexity, we open the door to new functional applications that were previously out of reach. And, importantly, we demonstrate the reproducibility of our method by providing a step-by-step guide for researchers in related fields."

The CTM method simplifies the synthesis of high-performance organic components, making them more practical for industrial use. Its scalability ensures that the transition from laboratory discovery to real-world application is smoother than ever before. The study marks a crucial step in the integration of advanced chemical synthesis into everyday technology. As industry pushes for sustainable, high-performance materials, innovations like this will help shape the future of materials science.

Original Publication

Josue Ayuso-Carrillo, Davide Bonifazi. Catalyst-Transfer Macrocyclization Protocol: Synthesis of π-conjugated Azaparacyclophanes Made Easy. In JACS Au. 

DOI: 10.1021/jacsau.5c00109