Design of New V Shaped Thermotropic Liquid Crystals containing Heterocyclic

The characterization and design of this study of new liquid crystals with were reported. This study reported the characterization and design of new liquid crystals with a V shape compounds containing thiazolidine-2,4-dione and 1,3-phenylene as a core unite with mesophase properties. Chloroacetic acid, water, and thiourea were used to prepare thiazolidine-2,4-dione [I] in the presence of strong hydrochloric acid. The 4-hydreoxybenzaldehyde and n-alkyl bromide were reacted with potassium hydroxide to create the n-alkoxy benzaldehyde, and then the compound [I] reacted with [II] n in the presence of piperidine to produce compounds [III] n . In addition, resorcinol was converted to a corresponding compound [IV] by refluxing pyridine and DMF with two moles of chloroacetyl chloride; the compounds [III] n and [IV] were then interacted with sodium acetate to form compounds [V] n. . FT-IR and 1 HNMR spectroscopy were really used to determine the structures of the produced substances. Using polarized optical microscopy, these mesogens' mesomorphic characteristics were studied (POM).The synthesized molecules exhibited enantiotropic liquid crystal phases; the substances [V] 1-4 exhibited an only the enantiotropic nematic phase.

order to create a mesogenic molecule, it is crucial to select the right core, connecting unit, or terminal group.
In the course of researching heterocyclic liquid crystal derivatives, various thermotropic liquid crystals with heterocyclic units have been created over a long period of time. [5,6] In line with our investigation of heterocyclic unit-containing derivatives of liquid crystals, various thermotropic liquid crystals with heterocyclic units have been created over a long period of time. [7][8][9]. The geometry of rigid-cored calamitic molecules has been thought to be the most conducive to mesogenic activity. [10]. Therefore, understanding the link between structure and property is crucial when developing new liquid crystal materials. Numerous mesogens have been created and studied as a result of the utilization of novel thermotropic liquid crystals [11]. Examples of real-world LC applications in science and technology include display devices, photoconductors, organic light-emitting diodes, and semiconductor materials. [12][13][14].
In this paper, we synthesize a new V homologous series bearing two arms containing thiazolidine-2,4-dione with an alkoxy chain and study their liquid crystal properties. There are no known substances with properties and synthesis identical to those of liquid crystals. Based on the various alkoxy chains' lengths, the liquid crystalline compounds' characteristics were explained. Understanding the impact of these molecules' skeletal structures and their capacity to induce the liquid crystal mesophase is the primary goal of this work.

Experimental
Materials were obtained from Merck Co., Fluka, and Aldrich.

Techniques
With the TMS serving as an internal standard, the compounds were dissolved in DMSO-d6 solution; the 1 H-NMR Spectra were measured at 400 MHz by the company Bruker and reported in ppm (δ). SHIMADZU recorded FT-IR spectra (IR Affinity -1 ) in the 400-600 cm -

Preparation of theThiazolidine-2,4-dione [I]
A flask of 250 ml with three necksa was filled with a mixture of 45.6g (0.6M) of thiourea and 56.4g (0.6M) of chloroacetic acid. The mixture was left until the appearance of white precipitat thin it was agitated for 15 minutes at 100-110 °C, the reaction mixture was agitated and refluxed for 10-12 hours. At this point, 60 ml of concentrated hydrochloric acid was carefully added using a falling funnel to dissolve the precipitate. The mixture of reactions solidified into a mass of white needle clusters after cooling to get rid of any remaining hydrochloric acid. The filtered item was washed with water, dried, and then recrystallized from ethanol, yielding 80%, M.P 123-125 °C [15].
Synthesis of 5-Arylidene-thiazolidine-2,4-dione: General Procedure [III]n A mixture of compound [I] (2.21g, 0.01mole) and aromatic aldehyde[II]n (0.01mole) with 5mL ethanol was refluxed for three hours while piperidine (0.5mL) was present. The product was then cooled before being placed in cold water. The solid was cleaned, dried, and recrystallized from acetone after filtering and cleaning.

Results and Discussion
Equimolar amounts of thiourea and chloroacetic acid were reacted to produce 2,4thiazolidinedione

Liquid Crystalline Properties
The properties of liquid crystalline compounds were assessed using polarized optical microscopy [V]n (POM). Under polarized light and at a specific temperature, POM exhibits liquid crystal characteristics. The values for the transition temperatures were shown in Table 1. Microscopy examinations were used to determine the mesophase's texture using the Richter [19] and Gray and Goodby categorization systems. [20]. Novel symmetrical compounds bearing two arms containing Thiazolidine-2,4-dione with connected to the core by 1,3-phenylene were successfully synthesized via many-steps. Thus, it can be inferred that in order to manage the phase-transition properties of LC compounds, it is crucial to consider both the molecular geometry and the length of the flexible alkoxy unit. Only under POM is there an enantiotropic nematic phase in the compounds [V]1-4, as seen by the texturing of the nematic phase in figures (2a-d), respectively. The alkoxy chain of series [V]n's transition temperature is plotted. Consider Figure 3's n, which represents the number of carbon atoms. This behavior can be characterized in terms of the terminal/lateral (t/l) contact forces ratio, resulting from the size of the alkoxy terminal chain. When this ratio is high, chemicals produce fewer organized mesophases (nematic mesophase), and when it is low, compounds produce more ordered mesophases (smectic phase).