Helicenes are a group of polycyclic aromatic hydro­car­bons (PAHs) with screw-shaped struc­tures that give rise to charac­ter­is­tic optical and optoelec­tronic proper­ties. Both expan­sion of the helical struc­ture and its enrich­ment with boron have been proved to enhance these proper­ties, enabling multi­ple appli­ca­tions, for example in OLEDs and OFETs. This project focuses on the synthe­sis of helicenes integrat­ing both features as poten­tial new materi­als for organic electron­ics and funda­men­tal studies. 

Helicenes are a group of non-planar polycyclic aromatic hydro­car­bons (PAHs) exhibit­ing appeal­ing optoelec­tronic proper­ties and there­fore showing poten­tial for appli­ca­tions in organic electron­ics and bioimag­ing. These compounds have been inves­ti­gated as semicon­duc­tors in organic field-effect transis­tors (OFETs) and as spin filters. More recently, they have been inten­sively studied as chiral emitters in state-of-the-art circu­larly polar­ized organic light-emitting diodes (CP-OLEDs).

Among the factors that can influ­ence helicene proper­ties, the three most impor­tant are: 1) the helical and lateral exten­sion of the helical struc­ture, 2) the presence of hetero­cy­cles in the molec­u­lar skele­ton, and 3) the ring connec­tion pattern (angularly or linearly fused rings). The aim of this project is to combine these three compo­nents to obtain boron- and nitro­gen-embed­ded, expanded helicenes with maximized optical proper­ties (Figure 1).

To achieve this goal, we apply a modular approach, where oligoaryl subunits are coupled and later fixed into a three-dimen­sional helical struc­ture by the intro­duc­tion of boron atoms. Synthe­sis of a series of new build­ing blocks with unusual substi­tu­tion patterns is neces­sary to obtain the target molecules. This project will not only contribute to the under­stand­ing of the impact of helical struc­ture expan­sion and exten­sion on its proper­ties, but will also provide new tools for the design and synthe­sis of organic materials.