Optical and calorimetric studies of quercetin-doped liquid crystals: Effects of molecular aggregation

• Published in: Journal of molecular liquids 2019-12, Vol.295, p.111689, Article 111689
• Main Authors: Samoilov, A.N., Minenko, S.S., Sushynskyi, O.Ye, Lisetski, L.N., Lebovka, N.I.
• Format: Article
• Language: English
• Subjects: Aggregation; Liquid crystals, cholesterics; Nematics; Quercetin
• ISSN: 0167-7322
• DOI: 10.1016/j.molliq.2019.111689

The organic substance quercetin, when added to liquid crystal (LC) systems as non-mesogenic dopant significantly affects properties of the LC host. The microphotographs of cholesteric (M5) and nematic (5CB) LC textures evidenced about presence of aggregation quercetin molecules in LC hosts. These results are in agreement with literature data on quercetin in lyotropic phases of phospholipid membranes. The effects of quercetin on phase transition temperatures from cholesteric/nematic to the isotropic state, as well as shapes of the corresponding calorimetric peaks, were studied by differential scanning calorimetry. Optical behavior of M5 and 5CB doped with quercetin was studied as function of temperature and concentration of quercetin. The data evidenced that quercetin can be considered as a certain intermediate agent between fully solvable non-mesogenic dopants and dispersed nanoparticles, combining partial solubility and formation of nano-sized aggregates inside LC medium. [Display omitted] •Nematic and cholesteric liquid crystal (LC) systems doped with quercetin were studied.•Optical transmission vs. temperature and concentration is similar to LC with dispersed nanoparticles.•Effects of quercetin on LC phase transitions were dependent on LC chemical structure.•Evidence of molecular aggregation of quercetin in LC medium is presented