New Luminescent Liquid Crystals Based on 2,1,3-Benzothiadiazole and Bent Five-membered<i>N</i>-Heterocyclic Cores

Gallardo, Hugo; Conte, Gilmar; Tuzimoto, Patricia; Behramand, B.; Molin, Fernando; Eccher, Juliana; Bechtold, Ivan H.

doi:10.1080/02678292.2012.698313

Cited by 72 publications

(21 citation statements)

References 34 publications

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“…Early reports on studies of tetrazine dyes identified liquid-crystalline phases exhibited by the dyes themselves, [61,62] and although devices tend not to utilise dyes alone as the anisotropic medium, the solubility of these compounds was found to be particularly high (10-20 mol%) in other nematic hosts. [45] Much more recently, there have been reports of dyes from other classes exhibiting mesophases themselves, including compounds based on the typically much more stable benzothiadiazole, [63] anthraquinone [64] and indigo [65] chromophores, and examples of these are shown in Figure 6. Such studies demonstrate the potential for a high degree of compatibility between guests and hosts, potentially providing a route to overcoming solubility difficulties such as those outlined for anthraquinones above, enabling mixtures exhibiting intense colours to be formulated, and enabling chromophores previously discounted for use in guest-host systems on solubility grounds to be considered.…”

Section: Dyes As Thermotropic Liquid Crystalsmentioning

confidence: 98%

Dyes as guests in ordered systems: current understanding and future directions

Sims

2016

Liquid Crystals

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The optical properties of dyes dissolved in liquid crystals have led to their proposed use in a diverse range of practical applications. Such guest-host systems are typically required to fulfil a range of criteria relating to their absorption properties, degree of alignment and stability, but concurrently satisfying these requirements has proven a barrier to their widespread use. In this article, many of the proposed applications and their requirements are discussed, and an outline of some of the most prevalent classes of dye proposed in the context of guest-host systems is given, along with a summary of recent reports of dyes that exhibit thermotropic mesophases. Theoretical approaches to describing the alignment within guest-host systems are outlined, and possible strategies for the future rational design of guest-host systems are discussed. ARTICLE HISTORY

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Section: Dyes As Thermotropic Liquid Crystalsmentioning

confidence: 98%

Dyes as guests in ordered systems: current understanding and future directions

Sims

2016

Liquid Crystals

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“…The samples were prepared using procedures previously described in the literature. 28 The scans were performed in continuous mode from 2 to 30 (2q angle) with the samples in the mesophase by cooling from the isotropic.…”

Section: Materials and Instrumentationmentioning

confidence: 99%

Synthesis and characterization of some novel tetrazole liquid crystals

et al. 2013

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The synthesis and characterization of new 4-[(2-alkyl)-2H-tetrazol-5-yl]phenyl 4-alkyloxybenzoates (5a-i) and 5-{4-[(4-substituted)benzyloxy]phenyl}-2-alkyl-2H-tetrazoles (7a-e) are reported. The reported tetrazoles contain two alkyl chains (six to ten carbon atoms) except for 5h and 7e which have a chiral citronellyl group linked at the N-2 nitrogen atom of the tetrazole ring and 5i having a bromine atom at the para position of benzoate. The regiochemistry in the alkylation step was established unequivocally by single-crystal X-ray analysis for 5a and 5f. The regioselectivity in the alkylation step was also confirmed by analysis of 13 C NMR chemical shifts of the C 5 carbon atom in the tetrazole ring and the methylene carbon atom vicinal to the nitrogen atom. The mesogenic behavior of the liquid crystals was characterized by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The tetrazolyl benzoates 5a-h show a nematic mesophase. The lengthening of alkyl chains favors the appearance of the smectic mesophase. For instance, 5g displayed nematic and smectic C mesophases, while 5h which has the chiral citronellyl group displayed nematic and smectic A mesophases. Tetrazoles 7a-e did not show mesomorphic behavior mainly due to replacement of the carbonyl by a methylene group.

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“…[33] On the basis of these points, we synthesised and investigated the mesomorphic properties of some new long-chain-derived 3,5-substituted pyrazoles (12a-c) and isoxazole compounds (13a-d). Compounds 12b and 13b are reproduced here to serve as reference compounds as well as to plot transition temperatures with respect to number of carbon atoms at terminal alkyl chain.…”

Section: Mesomorphic Propertiesmentioning

confidence: 99%