Low-temperature nematic phase in asymmetrical 1,3,4-oxadiazole bent-core liquid crystals possessing lateral methoxy group |
| |
Authors: | Sandip Kumar Saha Achu Chandran P K Khanna A M Biradar |
| |
Institution: | 1. Department of Chemistry, Assam University, Silchar, India;2. Advanced Packaging Group, CSIR-Central Electronics Engineering Research Institute (CEERI), Pilani, India;3. Liquid Crystal Group, CSIR-National Physical Laboratory (NPL), New Delhi, India |
| |
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. |
| |
Keywords: | Bent-core mesogens 1 3 4-oxadiazole Nematic phase Photophysical studies |
|
|