Low-temperature nematic phase in asymmetrical 1, 3, 4-oxadiazole bent-core liquid crystals possessing lateral methoxy group. Issue 11 (2nd September 2017)

• Record Type: Journal Article
• Authors: Saha, Sandip Kumar; Paul, Manoj Kumar; Chandran, Achu; Khanna, P. K.; Biradar, A. M.
• Is Part Of: Liquid crystals. Volume 44:Issue 11(2017)
• Page Start: 1739
• Page End: 1750
• Publication Date: 2017-09-02
• Subjects: Bent-core mesogens -- 1, 3, 4-oxadiazole -- Nematic phase -- Photophysical studies; Liquid crystals -- Periodicals; 548.905
• DOI: 10.1080/02678292.2017.1336678
• Languages: English
• ISSNs: 0267-8292

Abstract

ABSTRACT: Asymmetrical bent-core molecules based on 1, 3, 4-oxadiazole bent-core unit have been synthesised as a new design with a lateral methoxy group at outer phenyl ring of the molecule. These new asymmetrical bent-core molecules resemble hockey-stick shaped due to the presence of two different arms of different lengths. One arm of these molecules is elongated having two phenyl rings and possesses a 4- n -alkyloxy chain of a different number of carbon atoms ( n = 4, 8, 12 and 18) and other arm is short and has one phenyl ring with fixed 4- n -octyloxy chain. The bent-core molecules possess a lateral polar methoxy group at the elongated arm of the molecule. These bent-core compounds exhibited fluorescence emission in the UV wavelength region (~377–386 nm) whereas in acetonitrile and dimethylformamide, solvent displays blue emission peak with a large stoke shift.The bent-core molecules with the number of carbon atoms ( n = 4, 8 and 12) at the elongated arm exhibited monotropic nematic phase at low temperature, while the 4- n -octadecyloxy chain at the elongated arm displayed smectic A phase. Dielectric studies were performed in the nematic phase of the bent-core mesogens confirm the formation of the cybotactic cluster in the nematic mesophases. GRAPHICAL ABSTRACT: