Physical, Electro-Optical, and Spectroscopic Properties of I52 Liquid Crystal: A Computational Study

,, Tikaram; Kumar, Ravinder; Kumar, Yogesh; Kumar, Narinder

doi:10.22075/ppam.2026.39618.1184

Physical, Electro-Optical, and Spectroscopic Properties of I52 Liquid Crystal: A Computational Study

Document Type : Original Article

Authors

Tikaram , ¹

Ravinder Kumar ²

Yogesh Kumar ¹

Narinder Kumar ¹

¹ Department of physics, School of applied and life sciences (SALS), Uttaranchal University, Dehradun, India-248007

² Department of mathematics, MMEC, Maharishi Markandeshwar (Deemed to be) University, Mullana, Ambala, India

10.22075/ppam.2026.39618.1184

Abstract

We have investigated the intrinsic molecular-level electronic, spectroscopic, and electric-field-dependent properties of 4-Ethyl-2-fluoro-4'-[2-(trans-4-pentylcyclohexyl)-ethyl] biphenyl (which is known as I52) using hybrid functional B3LYP with 6-31G basis set within Density Functional Theory (DFT) method. Dipole moment of I52 increases linearly with external electric field. UV spectra of I52 shows a sharp peak at 258 nm. Raman Spectra reveals C-H bonding (2800-3000cm^-1) is due to substituted ethyl and pentyl-cyclohexyl groups. FTIR spectra reveals C-H stretching vibrations at 3028 cm^-1 due to alkyl side chains and trans-configuration of the pentyl-cyclohexyl moiety. HOMO-LUMO energy gap is found to be 5.08 eV, which makes I52 suitable for insulating applications. Structurally, I52 has a biphenyl core carrying an ethyl group and a fluorine atom on one phenyl ring and a large trans-4-pentylcyclohexylethyl substituent on the other, which is producing unique molecular anisotropy. The fluorine atom improved the dielectric anisotropy, which also leads to higher electro-optic effect. Hence, I52 continues to be a vital material in the study of fundamental liquid crystal science as well as in the application areas where customized molecular properties and good electro-optical performance are essential.

Keywords

I52

Liquid Crystal

DFT

FTIR

Subjects

New materials: Theory, Design, and Fabrication (simulation and modeling)

© 2026 The Author(s). Progress in Physics of Applied Materials published by Semnan University Press. This is an open access article under the CC-BY 4.0
license. (https://creativecommons.org/licenses/by/4.0/)

[1] Sonin, A.A., Yethiraj, A., Bechhoefer, J. and Frisken, B.J., 1995. Temperature-induced orientational transitions in freely suspended nematic films. Physical Review E, 52(6), pp.6260–6266.
[2] Manev, E., Proust, J.E. and Ter-Minassian-Saraga, L., 1977. Structural disjoining pressure in thin films of liquid crystals. Colloid & Polymer Science, 255(11), pp.1133–1135.
[3] Kumar, N., Singh, P., Thapa, KB., Upadhyay, P. and Kumar, D., 2021. Molecular spectroscopy and electro-optical effect of I52 liquid crystal molecules studied under the influence of an external electric field (THz): a theoretical approach. Journal of Molecular Modeling, 27(1), p.11.
Tikaram / Progress in Physics of Applied Materials 6 (2026) 315-330 329
[4] Vieweg, N. and Koch, M., 2010. Terahertz properties of liquid crystals with negative dielectric anisotropy. Applied Optics, 49(29), pp.5764–5767.
[5] Dziaduszek, J., Dabrowski, R., Ziołek, A., Gauza, S. and Wu, S., 2009. Syntheses and mesomorphic properties of laterally fluorinatedphenyl isothiocyanatotolanes and their high birefringent mixtures. Opto-Electronics Review, 17(1), pp.20–24.
[6] Tsai, T.R., Chen, C.Y., Pan, R.P., Pan, C.L. and Zhang, X.C., 2004. Electrically controlled room temperature terahertz phase shifter with liquid crystal. IEEE Microwave and Wireless Components Letters, 14(2), pp.77–79.
[7] Balkwill, P., Bishop, D., Pearson, A. and Sage, I., 1985. Fluorination in nematic systems. Molecular Crystals and Liquid Crystals, 123(1), pp.1–13.
[8]Dunmur, D., Hitchen, D. and Xi-jun, H., 1986. The physical and molecular properties of some nematic fluorobiphenylalkanes. Molecular Crystals and Liquid Crystals, 140(1), pp.303–318.
[9] Becke, A., 1993. Density-functional thermochemistry. III. The role of exact exchange. The Journal of Chemical Physics, 98(7), p.5648.
[10] Lee, C., Yang, W. and Parr, R.G., 1988. Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Physical Review B, 37(2), p.785.
[11] Hay, P.J. and Wadt, W.R., 1985. Ab initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg. The Journal of Chemical Physics, 82(1), pp.270–283.
[12] Wang, Y., Wang, F., Li, J., Huang, Z., Liang, S. and Zhou, J., 2017. Molecular structure and electronic properties of triolein molecule under an external electric field related to streamer initiation and propagation. Energies, 10(4), p.510.
[13] Kumar, N., Singh, P., Upadhyay, P., Chaudhary, S. and et al., 2020. Odd–even effect of 7O. m liquid crystal compound series studied under the effect of the electric field by density functional theory (DFT) methods. The European Physical Journal Plus, 135(5), p.388.
[14] Kumar, N., Singh, P., Thapa, K.B. and Kumar, D., 2020. Molecular spectroscopy and adverse optical properties of N-(p-hexyloxy-benzylidene)–p-toluidine (HBT) liquid crystal molecule studied by DFT methodology. IOP SciNotes, 1(1), p.015202.
[15] Kumar, Y., Rawat, B.S. and Kumar, N., 2024. Influence of Electric Field on the Spectroscopic and Opto-electronic Properties of 10ABP: A DFT Study. Jordan Journal of Chemistry (JJC), 18(3), pp.119-128.
[16] Kumar, Y. and Kumar, N., 2023. Electro-optical Effect of 4-n-alkyl-sulfanyl-4' isothiocyanate-biphenyl Liquid Crystal Homologous Series Under Terahertz Frequency: A Theoretical Approach. Makara Journal of Science, 27(4), p.1.
[17] Li, J., Mo, L., Che, Z., Li, J., Hu, M., Wan, D. and An, Z., 2022. New multi-fluorinated benzofuran liquid crystals with large dielectric anisotropy and improved solubility. Liquid Crystals, 49(13), pp.1753–1762.
[18] Duan, L., Shi, D., Chen, P., Zhang, L., Ren, L., Chen, X. and An, Z., 2017. Preparation and characterisation of laterally monofluorinated mesogenic benzimidazole-based compounds. Liquid Crystals, 44(11), pp.1678–1685.
[19] Ahmed, H.A. and Aboelnaga, A., 2021. Synthesis and mesomorphic study of new phenylthiophene liquid crystals. Liquid Crystals, 49(6), pp.804–811.
[20] Xie, N., Du, S., Chen, R., Liu, G., Chen, P., Weng, Q., Wang, J., Gao, A., Chen, X. and An, Z., 2021. Synthesis and properties of benzoxazole-terminated mesogenic compounds containing tolane with high birefringence and large dielectric anisotropy. Liquid Crystals, 48(14), pp.1978–1991.
[21] Hu, K., Chen, P., Chen, X. and An, Z., 2015. Synthesis and Characterization of Mesogenic Compounds Possessing Bithiophene and Benzoxazole Units. Molecular Crystals and Liquid Crystals, 608(1), pp.25–37.
[22] Weng, Q., Duan, L., Chen, P., Gao, A., Chen, X. and An, Z., 2019. Synthesis and mesomorphic properties of the nematic mesophase benzoxazole derivatives with big twist angle of difluoro-biphenyl unit. Liquid Crystals, 46(7), pp.1013–1023.
[23] Zhang, M., Du, S., Yuan, D., Chen, P., Liu, G., Dang, J., Chen, X. and An, Z., 2021. Benzoxazole-based nematic liquid crystals containing ethynyl and two lateral fluorine atoms with large birefringence. Liquid Crystals, 48(2), pp.157–167.
[24] Liu, G., Ren, L., Zhang, M., Du, S., Chen, P., Gao, A., Chen, X. and An, Z., 2020. Synthesis and properties of benzoxazole-based liquid crystals containing ethynyl group. Liquid Crystals, 47(12), pp.1719–1728.
[25] Ahmed, H.A., Hagar, M. and Alhaddad, O., 2019. Mesomorphic and geometrical orientation study of the relative position of fluorine atom in some thermotropic liquid crystal systems. Liquid Crystals, 47(3), pp.404–413.
[26] Hagar, M., Ahmed, H.A., El-Sayed, T. and Alnoman, R., 2019. Mesophase behavior and DFT conformational analysis of new symmetrical diester chalcone liquid crystals. Journal of Molecular Liquids, 285, pp.96–105.
[27] Hagar, M., Ahmed, H.A. and Saad, G., 2019. Synthesis and mesophase behaviour of Schiff base/ester 4-(arylideneamino)phenyl-4″-alkoxy benzoates and their binary mixtures. Journal of Molecular Liquids, 273, pp.266–273.
[28] Alhaddad, O.A., Ahmed, H.A. and Hagar, M., 2020. Experimental and Theoretical Approaches of New Nematogenic Chair Architectures of Supramolecular H-Bonded Liquid Crystals. Molecules, 25(2), p.365.
[29] Praveen, L., 2021. Nematic and smectic bithiophenes for UV sensing mechanism: Comparative calculations on different homologues. Journal of Molecular Liquids, 341, p.117424.
[30] Chen, R., Huang, Y., Li, J., Hu, M., Li, J., Chen, X., Chen, P., Wu, S.T. and An, Z., 2019. High-frame-rate liquid crystal phase modulator for augmented reality displays. Liquid Crystals, 46(2), pp.309–315.
[31] Klasen, M., Bremer, M., Götz, A., Manabe, A., Naemura, S. and Tarumi, K., 1998. Calculation of Optical and Dielectric Anisotropy of Nematic Liquid Crystals. Japanese Journal of Applied Physics, 37(8R), p.L945.
[32] Kumar, Y., Ram, T. and Kumar, N., 2025. Comparative Density Functional Theory Approaches for Investigating the Electro-Optical Properties of 5CB Liquid Crystal Molecules. Progress in Physics of Applied Materials, 5(2), pp.187-198.
[33] Ram, T., Kumar, Y. and Kumar, N., 2026. Investigation of Physical, Opto-Electronics and Insulating Properties of PPPCC Liquid Crystal Molecule by Density Functional Theory (DFT) Method: A Theoretical Approach. East European Journal of Physics, (1), pp.266-273.
[34] Bulkin, B.J., 1976. Infrared and Raman Spectroscopy of Liquid Crystals. Applied Spectroscopy, 30(3), pp.261-269.
[35] Kumar, Y., Rawat, B.S. and Kumar, N., 2024. Influence of Electric Field on the Spectroscopic and Opto-electronic
330 Tikaram / Progress in Physics of Applied Materials 6 (2026) 315-330
Properties of 10ABP: A DFT Study. Jordan Journal of Chemistry (JJC), 18(3), pp.119-128.