ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

The synthesis, mesomorphic and dielectric investigation of new unsymmetrical bent-core mesogens derived from 3-hydroxybenzoic acid

Hale Ocak, Esma Ahlatcıoğlu Özerol, Fulya Çağla Çelikel, Mustafa Okutan, and Belkız Bilgin Eran

Department of Chemistry, Yildiz Technical University, Esenler, Istanbul, Turkey

E-mail: hocak@yildiz.edu.tr

Received: 22 February 2020  Accepted: 16 May 2020

Abstract:

Abstract

The synthesis, mesomorphic and dielectric investigation of new unsymmetrical bent-core mesogens derived from 3-hydroxybenzoic acid central core with linked two rodlike units carrying (S)-3,7-dimethyloctyloxy group and an n-alkyloxy chain at both terminals are presented. The liquid crystalline properties of the new unsymmetrical bent-core materials have been investigated by polarizing optical microscopy and differential scanning calorimetry. New compounds with the reversed ester linking unit exhibit a monotropic or enantiotropic columnar mesophase at lower temperatures as compared to analogs with a straight chain depending on the presence of the branched (S)-3,7-dimethyloctyloxy terminal chain. Dielectric measurements for one of the bent-core mesogens, 3-[[4-[[4-(octyloxy)benzoyl]oxy]benzoyl]oxy]benzoic acid 4-[[4-((S)-3,7-dimethyloctyloxy)phenoxy]carbonyl]phenyl ester (OBDPE), have been carried out on the angular frequency range from 25.12 to 50265k rad/s at different temperatures. Thanks to dielectric measurements, real and imaginary dielectric constant, conductivity mechanism and dielectric relaxation mechanism of OBDPE were obtained.

Graphic abstract

Keywords: Liquid crystals; Bent-core compounds; 3-Hydroxybenzoic acid derivatives; Columnar mesophase; Dielectric measurement

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-020-01203-4

Chemical Papers 74 (11) 3899–3911 (2020)