Abstract
Homolog series based on three aromatic rings bearing terminal alkoxy chain of various lengths named 4-(4-(alkoxy)phenylimino)methyl)phenyl nicotinate (An) were synthesized. The alkoxy-chain length changed between 6, 8 and 16 carbons. Mesomorphic and optical properties were carried out via differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Elemental analyses, FT-IR and NMR spectroscopy were carried out to elucidate the molecular structures of the prepared derivatives. Mesomorphic results indicated that all the synthesized homologs (An) are monomorphic possessing the nematic (N) phase enantiotropically with wide thermal stability. Computational simulations were measured via density functional theory (DFT) theoretical calculation tool. The estimated thermal and geometrical parameters are in agreement with the experimental data. By discussing the estimated parameters, it was found that the molecular architecture, dipole moment and the polarizability of the investigated compounds are highly affected by the length of the attached terminal flexible chain and the location of the nitrogen atom in the other terminal aromatic ring. Binary phase diagrams of two corresponding homologs with different proportionating terminals were constructed, and their binary phase physical properties were discussed in terms of the temperature range and stability of the N phase.
Highlights
Nowadays, liquid crystals (LCs) based on organic derivatives prove to have broad areas of industrial applications as optical technology and photoconductors [1,2,3]
Mesophase textures were identified by polarized optical microscopy (POM)
POM images showed schlieren texture of nematic (N) phase covering all members of present group all synthesized groups (An) upon heating and cooling (Figure 2)
Summary
Liquid crystals (LCs) based on organic derivatives prove to have broad areas of industrial applications as optical technology and photoconductors [1,2,3]. Insertion of heterocyclic pyridine ring in the LCs’ skeletons strongly impacts their polarizability and/or polarity as well as their geometric structures It extensively affects the phase transition temperature, types of mesophase and other physical and geometrical parameters essential for better properties of the LC materials [11]. Our team has centered its interest on the computational simulations of new synthesized LC materials to experimentally illustrate their mesophase properties in terms of theoretical estimations [26] These investigations were focused on the obtained mesomorphic transition results and the evaluated theoretical calculations correlations for investigated compounds. The goal of our investigation was to synthesize three-ring Schiff base/ester liquid crystals with a terminal heterocyclic ring (Scheme 1) and to investigate the effect of different proportionating of the terminal alkoxy chain length on the mesomorphic and optical behavior of synthesized derivatives.
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