Mesophase behavior and DFT conformational analysis of new symmetrical diester chalcone liquid crystals

• Published in: Journal of molecular liquids Vol. 285; pp. 96 - 105
• Main Authors: Hagar, M., Ahmed, H.A., El-Sayed, T.H., Alnoman, R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-07-2019
• Subjects: Angular liquid crystals; Chalcones; Conformational analysis; DFT; Angular liquid crystals; Chalcones; DFT; Conformational analysis
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2019.04.083

Synthesis, geometrical structures, conformational analysis, mesomorphic and optical characterizations of new angular chalcone liquid crystals, 4-(1,5-(3-oxopenta-1,4-dienyl))diphenyl bis-4-alkoxybenzoates, were investigated. These compounds contain chalcone core and diester phenyl rings attached to symmetrical terminal alkoxy chains with different number (n) of carbons from 6 to 16. Mesomorphic and optical properties were studied for the prepared homologues by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Elemental analyses, FT-IR, 1H, and 13C NMR spectroscopy were used for molecular structure confirmation. Density functional theory (DFT) theoretical calculations were estimated to confirm the experimental data and to deduce the most stable confirmal of prepared compounds. The results indicate that the stability of the conformers and the type of the mesophase are dependent on the length of the terminal alkoxy chains. Thermal parameters, dipole moments and polarizability of all estimated conformers were discussed. The relationships between the values of these parameters and the conformer type as well as the mesophase stability were illustrated.
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•New angular chalcone liquid crystals were prepared.•Shorter chains showed nematic phase while the longer smectic C.•V-shaped and U-shaped conformers were estimated from theoretical calculations.•Theoretical studies revealed that the polarizability, dipole moment and stability increase with the chain length increment.•The mesophase stability also increases as the chain length increases.