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Tailoring Chiral Discotic Liquid Crystals: Mesophase Engineering through Alternative Approaches and Chain Lengths

Hydrogen bonding is crucial in constructing superstructures in chiral discotic liquid crystals (DLCs) in chemical and biological systems due to its specific and directional nature. In this context, we achieved the successful synthesis of two branches of heptazine?based H?bonded complexes using distinct strategies. Hpz*?Es?Cn, we incorporated chiral alkyl tails (Hpz?chiral) onto the central C3 symmetric heptazine core, connected to achiral benzoic acid derivatives (Es?Cn acid) through H?bonding. Hpz?Es?Cn?acid* used an achiral heptazine derivative (Hpz?Es?Cn) linked to a chiral acid via H?bonding. On the other hand, based on the DSC results, we observed that Hpz*?Es?Cn complexes exhibited three distinct phases, whereas Hpz?Es?Cn?acid* complexes displayed only a single mesophase. In polarized optical microscopy (POM) observations, all the compounds displayed birefringence at room temperature, with the color of the POM images changing as the temperature varied. X?ray diffraction (XRD) studies at lower temperatures confirmed that Hpz*?Es?C8 exhibited the Colr phase, while Hpz*?Es?C10/12 exhibited the Colob phase. However, all the H?bonded complexes exhibited the Colh phase at higher temperatures. The chiroptical spectra captured by CD elegantly highlight the specific observations in the Col phase of two compounds, Hpz*?Es?C10 and Hpz*?Es?C12. This behavior has potential applications in various fields, including sensors, displays, and responsive materials.

Publication date: 21/11/2023



This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870292.