Utjecaj kiralnosti molekula s 3-aril-3-hidroksipropanoatnom skupinom na mezogena svojstva tekućih kristala

doctoral thesis

• Title (english): The influence of chirality of 3-aryl-3-hydroxypropanoate-based molecules on mesogenic properties of liquid crystals
• Author: Antonija Ožegović
• Mentor: Andreja Lesac (mentor)
• Committee member: Vesna Petrović Peroković (predsjednik povjerenstva)
• Committee member: Željka Soldin (član povjerenstva)
• Committee member: Marija Alešković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2024-07-16, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry
• Universal decimal classification (UDC): 54 - Chemistry. Crystallography. Mineralogy

Abstract

Zbog svojih optičkih i mehaničkih svojstava kiralni tekući kristali (LC) predstavljaju interesantne materijale za znanost i tehnologiju. U okviru ove doktorske disertacije sintetizirana je serija dimernih LC molekula s kiralnim centrom unutar fleksibilne razmaknice, uvedenim pomoću 3-aril-3-hidroksipropanoatne skupine. Molekule su sintetizirane u racemičnom i enantiomerno čistom obliku uz variranje duljine razmaknice i mezogene jedinice. Time je istražen utjecaj kiralnog centra u sprezi s paritetom razmaknice i različito polarizabilnim mezogenim jedinicama na mezogena svojstva dimera i njihovu sposobnost prijenosa kiralnosti na akiralni medij. Pokazano je da neparni dimeri posjeduju bogatiji mezomorfizam od parnih te je opažen efekt pariteta u prijenosu kiralnosti. Polarizabilnija mezogena skupina uz kiralni centar stabilizira mezogena svojstva te inducira temperaturnu inverziju zavojnice. Razlika u morfologiji površine između racemične i kiralne „twist-bend“ nematičke faze (N*TB) sugerira da kiralnost u razmaknici promiče kiralnu hijerarhiju. Ovi rezultati ističu važnost položaja i fleksibilnosti kiralne skupine unutar dimerne molekule za mezomorfna svojstva i prijenos kiralnosti.

Abstract (english)

Chiral liquid crystals (LCs) are promising materials for science and technology due to their optical and mechanical properties. Within this dissertation, a series of dimeric LC molecules with a chiral center within a flexible spacer, introduced via a 3-aryl-3-hydroxypropanoate group, were synthesized. The molecules were synthesized in racemic and enantiomerically pure forms with variations in the spacer length and mesogenic unit. The influence of the chiral center in conjunction with the spacer parity and differently polarizable mesogenic units on their mesogenic properties was investigated, as well as their ability to transfer chirality to an achiral medium. It was demonstrated that odd dimers exhibit a richer mesomorphism than even ones, and that chirality transfer was affected by the spacer parity. A more polarizable mesogenic group alongside the chiral center stabilizes mesogenic properties and induces a temperature inversion of the helix. The difference in surface morphology between the racemic and chiral N*TB phases suggests that chirality in the spacer promotes chiral hierarchy. These results highlight the importance of the position and flexibility of the chiral group within the dimeric molecule for mesomorphic properties and chirality transfer.

• Keywords: dimeri; efekt pariteta; kiralna indukcija; kiralna faza; kiralna razmaknica; tekući kristali
• Keywords (english): dimers; chiral induction; chiral phase; chiral spacer; liquid crystals; parity effect
• Language: croatian
• URN:NBN: urn:nbn:hr:217:696910
• Promotion: 2024
• Project: Number: IP-2019-04-7978; Title: Strukturna kiralnost vs molekulska kiralnost; Title: Structural Chirality vs Molecular Chirality; Acronym: SMChiral; Leader: Andreja Lesac; Jurisdiction: Croatia; Funder: Hrvatska zaklada za znanost; Funding stream: Research Projects
• Study programme: Title: Doctoral study; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica u području prirodnih znanosti (doktor/doktorica u području prirodnih znanosti)
• Type of resource: Text
• Extent: 116, XXXVIII str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-09-05 12:33:40