Affiliation:
1. Department of Chemical Science Indian Institute of Science Education and Research (IISER) Mohali Punjab 140306 India
2. Knowledge City Sector 81, SAS Nagar Manauli PO 140306 India
3. Centre for Nano and Soft Matter Sciences Bengaluru 560013 India
4. Department of Physics Patna University Patna 800005 India
Abstract
AbstractHydrogen (H)‐bonding is crucial in constructing superstructures in chemical (such as chiral discotic liquid crystals (DLCs)) as well as in 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. In Hpz‐Es‐Cn‐acid*, we 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 complexes 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 columnar rectangular (Colr) phase, while Hpz*‐Es‐C10/12 exhibited the columnar oblique (Colob) phase. However, all the H‐bonded complexes exhibited the columnar hexagonal (Colh) phase at higher temperatures. The chiroptical spectra recorded by Circular dichroism (CD) highlight the specific observations in the columnar phase of two complexes, Hpz*‐Es‐C10 and Hpz*‐Es‐C12. This behavior has potential applications in various fields, including sensors, displays, and responsive materials.
Subject
General Chemistry,Biochemistry,Organic Chemistry