On the Structure and Chiral Aggregation of Liquid Crystalline Star‐Shaped Triazines H‐Bonded to Benzoic Acids. Issue 66 (19th October 2020)

• Record Type: Journal Article
• Authors: Feringán, Beatriz; Cerdá, Jesús; Diosdado, Beatriz; Aragó, Juan; Ortí, Enrique; Giménez, Raquel; Sierra, Teresa
• Is Part Of: Chemistry. Volume 26:Issue 66(2020)
• Page Start: 15313
• Page End: 15322
• Publication Date: 2020-10-19
• Subjects: chirality -- liquid crystals -- self-assembly -- theoretical calculations -- triazine; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202001271
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The ability of a star‐shaped tris(triazolyl)triazine derivative to hierarchically build supramolecular chiral columnar organizations through the formation of H‐bonded complexes with benzoic acids was studied from a theoretical and experimental point of view. The combined study has been done at three different levels including the study of the structure of the triazine core, the association with benzoic acids in stoichiometry 1:3, and the assembly of 1:3 complexes in helical aggregates. Although the star‐shaped triazine core crystallizes in a non‐ C 3 conformation, the C 3 ‐symmetric conformation is theoretically predicted to be more stable and gives rise to a favorable C 3 supramolecular 1:3 complex upon the interaction with three benzoic acids in their voids. In addition, calculations at different levels (DFT, PM7, and MM3) for the 1:3 host‐guest complex predict the formation of large stable columnar helical aggregates stabilized by the compact packing of the interstitial acids by π–π and CH⋅⋅⋅π interactions. The acids restrict the movement of the the star‐shaped triazine cores along the stacking axis causing a template effect in the self‐assembly of the complex. Theoretical predictions correlate with experimental results, since the interaction with achiral or chiral 3, 4, 5‐(4‐alkoxybenzyloxy)benzoic acids gives rise to supramolecular complexes that organize in bulk hexagonal columnar mesophases stable at room temperature with intracolumnar order. The existence of supramolecular chirality in the mesophase was determined for complexes formed by acids derived from ( S )‐2‐octanol. Chiral aggregation was also evidenced for complexes formed in dodecane. Abstract : Made of stars : Theoretical and experimental studies demonstrate the intrinsic ability of star‐shaped 1:3 H‐bonded complexes to hierarchically build chiral supramolecular columnar organizations both in the liquid‐crystal phase and in solution. The theoretical approach, performed at a multiscale level, provides unprecedented insight on the template effect exerted by the H‐bonded benzoic acids to form the columnar arrangements.