Synthesis and Study of Mesomorphic Properties of Liquid Crystalline Compounds Involving Lateral -OCH3 Group and Vinyl Carboxylate Central Linkage

ABSTRACT

In the present investigation, a newly synthesized ester homologous series of mesogenic compounds having a vinyl carboxylate group as central linkage with two phenyl rings and a laterally substituted methoxy group as well as -CH=CH-COOC₄H₉ terminal end group were synthesized. Eleven homologues were synthesized. Among these eleven homologues first seven derivatives C₁ to C₇ of the investigated series are nonmesomorphic by nature. Rest of the homologs are smectic by nature, among these C₈, C₁₀ and C₁₂ homologues show monotropicaly smectic phase, while the last member of the series C₁₄ show smectic phase enantiotropicaly. Thus, presently investigated series is predominately smectogenic by nature without exhibiting nematic mesophase. Transition temperatures and textures of synthesized compounds were observed through an optical polarizing microscope equipped with a heating stage. The textures of smectogenic mesophase are focal conic fan-shaped. Some representative members were characterized by IR, ¹HNMR, mass spectroscopy and elemental analysis. Transition temperatures of homologues are plotted versus the number of carbon atoms present in n-alkyl chain of left n-alkoxy terminal end group. Isotropic-smectic / smectic-isotropic transition curve behaves in a normal ascending manner. Thermal stability and other mesogenic characteristics are compared with other structurally similar homologous series. The mesogenic phase length ranges between 5 ⁰C and 24 ⁰C and is of middle-order melting type.

References

• Reinitzer, F. Beiträge zur Kenntniss des Cholesterins. Monatshefte für Chemie 9, (1888) 421–441. https://doi.org/10.1007/BF01516710
• Gray, G. W. (1962) Molecular Structure and the Properties of Liquid Crystals, Academic Press: London.
• Demus, D., (1988). 100 years of Liquid Crystal chemistry. Cryst. Liq. Cry. 165, 45-84
• Eidenschink R. Liquid Crystals-New Compounds, New Applications. Wiley Online Library. https://doi.org/10.1002/anie.198914241
• Gray, G. S., & Jones, B. (1954). Mesomorphism and chemical constitution. Part II. The trans–p–n-alkoxycinnamic acids. Journal of Chemical Society 1467–1470
• Gray, G. W. (1979). Liquid crystals and molecular structure–Nematics and cholesterics. In G.R. Luckhurst and G.W. Gray (Eds.), The Molecular Physics of Liquid Crystals (pp. 1–30). Academic Press: London.
• H. Pandya, V. R. Patel, A. V. Doshi, Mesogenic Dependence of Chalconyl Schiff’s Bases on Molecular Rigidity and Flexibility. World Scientific News 86(3) (2017) 231-241
• Eidenschink R, Krause G, Pohl L. DE-B 26366844. 1976.
• Talwee, I., Shahi, S., Ramteke, V., & Syed, I. (2012). Liquid Crystals Pharmaceutical Application: A Review. International Journal of Pharmaceutical Research and Applications Sciences 1, 06–11
• Doshi, A. V., Bhoya, U. C., & Travadi, J. J. (2012). Determination of latent transition temperatures of nonmesomorphs by extrapolation method in binary systems. Molecular Crystals and Liquid Crystals, 552(1), 10-15
• Dave JS, Dewar MJS. Mixed Liquid Crystals. J Chem Soc. 1954; 4617
• Benbow SJ, Chan AW, Bowsher DR, et al. The Prediction of Diabetic Neuropathic Plantar Foot Ulceration by Liquid-Crystal Contact Thermography. Diabetes Care 1994; 17: 835-839
• Owsik J, Aleksander BS, and Elzbieta S. Use of Chiral Liquid Crystals in Laser Engineering. Society of Photo-Optical Instrumentation Engineers (SPIE) Digital Library. 1st March 1995, Vol. 2202: 185
• Vora, R. A., Prajapati, A. K., Kevat, J. B., & Rao, K. K. (2001). Mesogenic properties and the effect of 1, 2, 4 substitution on the central benzene nucleus: a three-ring mesogens. Liquid Crystals, 28, 983-989.
• Suthar, D. M., & Doshi, A. V. (2013). Title of the article. Molecular Crystals and Liquid Crystals, 575, 76-83
• Travadi J. J., Vadodaria, M. S., Ladva, K. D. and Doshi, A. V., (2016). Study of the Effect of Lateral Substitution on Mesogenic Behavior with Reference to -CH=CH- Unit, Cryst. Liq. Cryst. Vol. 626, 90-99.
• Travadi, J. J., Vadodaria, M. S., Ladva, K. D., & Doshi, A. V. (2016). Dependence of mesomorphism on molecular rigidity with reference to lateral substitution and central bridge. Molecular Crystals and Liquid Crystals, 626(1), 58-67
• Chaudhari, R. P., Chauhan, M. L., Chauhan, M. L., & Doshi, A. V. (2013). Synthesis and mesogenic behavior of novel liquid crystals with -CH=CH-CO- central bridge. Molecular Crystals and Liquid Crystals, 575(1), 88-95
• Patel, R. B., Chauhan, M. L., & Doshi, A. V. (2010). Synthesis and study of new homologous series of mesogens: n-butyl-p-(p’-n-alkoxy cinnamoyloxy) cinnamates. Der Pharma Chemica, 2(6), 157-164
• Dave J.S., Vora R.A. (1970). Mesomorphic Behaviour of the Cholesteryl Esters-I: p-n-Alkoxybenzoates of Cholesterol. In: Johnson J.F., Porter R.S. (eds) Liquid Crystals and Ordered Fluids. Springer, Boston, MA. https://doi.org/10.1007/978-1-4684-8214-0_38
• Vadodaria, M.S., Ladva, K.D., Doshi, A.V., & Travadi, J.J. (2016). Synthesis of novel ester series and study of its mesomorphism dependence on terminal end group with lateral –OCH₃ Molecular Crystals and Liquid Crystals, 624(1), 59-68.
• Chauhan, M. L., Pandya, R. N., & Doshi, A. V. (2011). Synthesis and Mesomorphism of Novel Liquid Crystalline: p-(p′-n-Alkoxy Benzoyloxy) Methyl Cinnamates. Molecular Crystals and Liquid Crystals, 548(1), 228-234. DOI: 10.1080/15421406.2011.591664
• Patel, R. B. (2011). Study of the Effect of Structural Variation on Mesomorphic Characteristics in Thermotropic Mesogenes (Doctoral dissertation). Saurashtra University, Rajkot, India.
• Greene T. W. &Wuts, P. G. M., Protective Groups in Organic Synthesis, 2nd Ed.; John Wiley and Sons: New York (1991).
• Prajapati, A. K., and H. M. Pandya. Effect of a lateral chloro group on azomesogens containing the naphthalene moiety. Molecular Crystals and Liquid Crystals 1 (2003) 31-39
• Jadav, N. D., Bharati A. Prajapati, and Ashish K. Prajapati. Azomesogens containing two fused ring moieties: synthesis and characterization. Molecular Crystals and Liquid Crystals 399, 1 (2003) 53-60
• Baku, N. K. (2023). Studies on Structure Property Relationship of Some Newly Synthesized Liquid Crystalline Compounds (Doctoral dissertation). Saurastra University, Rajkot, India.

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WSN 189 (2024) 116-131

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