Synthesis, Characterization, Gas Sensing and Anticancer Studies of New Ionic Liquid Crystalline Compounds

Abstract

In the present study, a novel four series of heterocyclic imidazole and benzoimidazole liquid crystalline were synthesized, characterized, sensor and anticancer evaluated. The synthesis of these liquid crystalline compounds involving alkylation (1a-1i, 2a, and 2b) and condensation reactions (3a-3r). The first series of novel derivatives imidazole dimers (4a-4i) were synthesized by incorporated reaction of imidazole ring with chalcone derivatives (3a-3i) with terminal chains in odd or even parity. The (4a-4e) Compounds are non-mesogenic, whereas (4f-4i) compounds exhibit enantiotropic SmA phases during the heating and cooling cycle. The second series of novel derivatives imidazole dimers (5a-5i) were synthesized by incorporated reaction of imidazole ring with chalcone derivatives (3j-3r) with terminal chains in odd or even parity. The (5a-5c) compounds are not shown liquid crystals property, while (5e-5i) compounds show enantiotrobic SmA phases during heating and cooling scans, which are revealed by POM and DSC. While (5d) compound exhibit monotropic SmA phase during cooling scan. The third series of novel derivatives benzimidazole dimers (6a-6i) have synthesized by incorporated reaction of benzimidazole ring with chalcone derivatives (3a-3i) with terminal chains in odd or even parity. The lower member of these series (6a-6c) did not exhibit liquid crystals property. While the higher member with longer terminal alkyl (6d 6i) chains exhibit enantiotropic SmA phase in heating and cooling scans. The fourth series of novel derivatives benzimidazole dimer (7a-7i) have synthesized by incorporated reaction of imidazole ring with chalcone derivatives (3j-3r) with terminal chains in odd or even parity. The (7a-7d) compounds did not show liquid crystals property, XIII while (7e-7i) compounds exhibit enantiotropic SmA phase in the heating and cooling cycle. The texture of SmA phase with focal conic fan-shape has been identified by POM at the heating and cooling processes of compounds in the four series with liquid crystals property. The structure of the liquid crystals compounds that have been synthesized has been elucidated by CHN Element analysis, FT-IR, 1D-NMR, and 2D-NMR techniques. The anti-cancer and anti-tumor activity of compounds (4c) and (6c) was studies by MTT assay, Morphological changes, and Acridine orange- Ethidium bromide (AO/EtBr) dual staining assay. The cytotoxicity determination on the human breast cancer MCF-7 cell line revealed that the compounds 4c and 6c are possessed high activity against the human breast cancer MCF-7 cell line. The gas sensing behavior of compounds (4i) and (6i) was studies by exposure the thin film of 4i and 6i-based sensors to reducing (NH3) and oxidizing gas (NO2). The sensitivity revealed that the 4i and the 6i-based sensor is possessed higher sensitivity to reducing gas than the oxidizing gas at room temperature. 4i-based sensor show a maximum sensitivity at room temperature.