Improving FLC Properties. Simplicity, Planarity, and Rigidity in New Chiral Oxazoline Derivatives

Abstract

In an attempt to develop new dopants for improved ferroelectric properties in liquid crystals, aryloxazolines have been chosen as chiral moieties. They were prepared in optically active form from (S)-p-amino alcohols via a short stereospecific synthesis and incorporated into mesogenic systems. Mesogenic and ferroelectric properties of 11 compounds in five series of chiral oxazoline derivatives [I(OH), I(H), II(OH), II(H), and III(OH)] have been studied. In order to establish the relationship between the molecular structure and ferroelectric properties, an indepth structural investigation of both H-bonded and non-H-bonded phenyloxazoline moieties was carried out (by means of semiempirical calculations-AM1-and spectroscopic studies-IR, UV and 'H NMR). These studies have proved a planar structure for both types of structures, which should have a strong influence on ferroelectric properties. These properties have been evaluated in 10 mol % binary mixtures. The highest Ps values were measured for compounds of series I(OH) [P, maxI(OH)a = 16.7 nC/cm2, P, maxI(OH)b = 13.2 nC/cm2] containing a hydrogen bond, which makes the chiral part of the molecule more rigid. Compound III(0H)a shows a wide SmC* phase range which supercools well below room temperature, and it has been studied as a ferroelectric liquid crystal in the pure state. The P, max measured is appreciably high: 225 nC/cm2. Its special thermal behavior (showing a glass transition at -28 "C) makes this compound very interesting from the point of view of practical applications and will be the target of further studies.

Switchable Columnar Metallomesogens

“…As explained at the end of the strategy section, it seemed reasonable to compare this result with the electrooptic behavior of a calamitic ferroelectric liquid crystal with a high tilt angle, about 458. [27] As can be seen in Figure 7, a strong similarity exists between the electrooptic responses of both the discotic and the calamitic molecules, when working at frequencies at which the material cannot easily follow the reversal of the field (1 Hz and 250 Hz, respectively). Such frequencies were chosen on the basis of the viscosity of the compounds.…”

Coordination chemistry and applications of metal phenolates containing an oxazoline group

“…A chiral congener of this series, 2-[(4S)-4,5-dihydro-4-benzyl-2-oxazolinyl]phenol, has likewise recently been characterised in a similar way (Luo et al 2010). This compound and its derivatives have found use in the design of larger ligand Brought to you by | University of Michigan Authenticated Download Date | 6/15/15 3:26 PM frameworks, such as oxazolinyl-functionalised pyrrolylphosphines (Gavrilov et al 2004(Gavrilov et al , 2005, and are useful precursors for the formation of functionalised polymers (Wörner et al 1995;Lustoň et al 2006), liquid crystals (Serrano et al 1995), and as molecules for the selective detection of metals such as Zn via formation of metal-phenolate complexes (Zhang et al 2004;Son et al 2008). …”

trans-Bis[(S)-2-(4-ethyl-4,5-dihydro-1,3-oxazol-2-yl)phenolato-κ2N,O]copper(II)

“…For related literature, see Chelucci (1997); Du et al (2003); Ghosh et al (1998); Ji et al (1999); Imai et al (1996); Zhang et al (2007). For synthesis, see: Serrano et al (1995).…”