Proceedings of International Conference on Applied Innovation in IT
2026/03/31, Volume 14, Issue 1, pp.619-627

Liquid Crystalline Behavior and Optoelectronic Potential of Novel Schiff Base Derivatives


Jehan A. Sulaiman, Hanaa K. Salih, Mohammed M. Aftan and Nagham Q. Kadhim


Abstract: In this study, a new series of Schiff bases was synthesized through the condensation of azo dyes with the antidiabetic drug metformin. The structures of the synthesized compounds were confirmed using FT-IR and ^1H-NMR spectroscopy, while their liquid crystalline behavior was investigated using POM and DSC techniques. The results revealed that most of the synthesized compounds exhibited Smectic-A and Nematic liquid crystalline phases upon heating, indicating monotropic behavior. This behavior is attributed to the rod-like molecular structure formed by the aromatic rings, the polarizable terminal substituents (Cl, Br), and the azomethine (C=N) and azo (N=N) groups, which enhance intermolecular interactions and molecular alignment .It was also observed that the presence of a chloro substituent provides higher thermal stability to the nematic phase compared to the bromo substituent due to its higher electronegativity and polarization effect .FT-IR results confirmed the disappearance of the characteristic bands of the primary amine and aldehyde carbonyl groups, along with the appearance of a new band corresponding to the azomethine group at 1630 cm⁻¹. Additionally, ^1H-NMR spectra showed characteristic signals consistent with the proposed structures of compounds 1, 2, and 3, whereas compounds 5, 6, and 7 lacked the signal attributed to the methoxy group due to its absence in their structures. Rod-like Schiff bases with aromatic, azomethine, and azo groups formed stable smectic phases, while polarized terminal groups promoted nematic phase stability. Chlorine substitution enhanced the thermal stability of the nematic phase compared to bromine.

Keywords: Schiff Bases, Metformin Derivatives, Liquid Crystal, Smectic Phase, Nematic Phase.

DOI: Under indexing

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