[n]Helicene Diimides: A Twist in Diimide Chemistry

The introduction of chirality in conjugated organic compounds gives rise to properties such as absorption and emission of circularly polarized light, spin-selective charge-transport, and magneto-chiral anisotropy, which enable conceptualization of new functions.

Therefore, chiral organic semiconductors (OSCs), which utilize both charge and spin of the carriers, are needed as new materials to drive the development of next-generation (opto)electronics such as spin-LEDs, 3D displays, and quantum-based optical computing.

While the field of OSCs has matured, there is an urgent need for chiral OSCs, which can offer high charge-carrier mobilities along with the strong chiroptical response to transform the laboratory-based proof-of-concept research on chiral OSCs into real-world applications.The objective of the proposed research is to develop chiral OSC materials, which will exhibit (i) effective chiroptical responses, (ii) high fluorescence quantum yields, and (iii) dynamic spin-selective charge-transport.To achieve this goal, I plan to develop a new class of functional chiral molecules, namely, [n]helicene diimides ([n]HDI), where two six-membered imide moieties are spanned by an [n]helicene spacer.

The proposed research bridges two well-established research fields: (i) planar polycyclic aromatic hydrocarbons bearing diimide units, which are excellent semiconductors, and (ii) 3D [n]helicenes, which display strong chiroptical responses.

The research plan will capitalize on three synthetic strategies: (1) A small-molecule approach to gain a fundamental understanding of the structure-function relationship, originating from the through-bond and through-space coupling between imide moieties. (2) A multi-helicene approach to expand the application scope by taking control over the electronic energy levels and self-assembly behavior. (3) Macromolecular approach to develop homochiral multifunctional materials employing enantiopure [n]HDIs as molecular synthons.