Convergent Synthesis of Columnar Twins and Tetramers from Triphenylene Building Blocks – The First Example of a Columnar Spiro-Twin

Schulte, Jörg; Laschat, Sabine; Vill, V.; Nishikawa, Etsushi; Finkelmann, Heino; Nimtz, Manfred

doi:10.1002/(sici)1099-0690(199811)1998:11<2499::aid-ejoc2499>3.0.co;2-l

Cited by 58 publications

(39 citation statements)

References 34 publications

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“…Therefore we decided to investigate such a system, which would further support the importance of micro-segregation for selforganization in liquid crystals. [11] This concept has previously been demonstrated for thermotropic cyclohexanes, [12] carbohydrates, [13] pentaerythritbenzoates [14] and -ethers, [15] and dendrimers. [16] The results towards this goal are reported in this paper.…”

Section: Introductionmentioning

confidence: 99%

Columnar Liquid Crystals with a Central Crown Ether Unit

Schultz

Laschat²,

Saipa

et al. 2004

Adv Funct Materials

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Novel columnar liquid crystals 5a–f bearing a dibenzo[18]crown[6] central unit have been prepared from bromodialkyloxybenzenes 1 and tetrabromodibenzo[18]crown[6] 2 via Suzuki coupling reactions. Differential scanning calorimetry (DSC) revealed that the length of the alkyl chains in the liquid‐crystalline compounds 5 influenced their mesomorphic properties. Whereas 5a–d gave fan‐shaped textures only upon rapid cooling, 5e and 5f with C9 and C10 side chains formed stable columnar textures upon slow cooling. A hexagonal columnar mesophase of 5a is apparent from X‐ray diffraction studies. Complexation of 5 with potassium significantly shifted the clearing points to higher temperatures and also increased the mesophase stability in the cooling cycle.

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Section: Introductionmentioning

confidence: 99%

Columnar Liquid Crystals with a Central Crown Ether Unit

Schultz

Laschat²,

Saipa

et al. 2004

Adv Funct Materials

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“…1.2.2 Synthesis of 2-hydroxy-3-methoxy-6,7,10,11-tetra(alkyloxy)triphenylenes 1(n). 1(n) series compounds were synthesized according to the modification of reported method [39] . Synthetic procedure of 1(5) was given below as an example.…”

Section: Synthesis Of Intermediatesmentioning

confidence: 99%

Synthesis and mesomorphism of diacetylene-bridged triphenylene discotic liquid crystal dimers

Zhao

et al. 2009

Sci. China Ser. B-Chem.

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m -C≡≡ C-] 2 , 8(m), (m = 1, 3) by Eglinton coupling reaction. The thermotropic liquid crystal properties were studied by differential scanning calorimetry and polarized optical microscopy. The results are showed as follows: the length of peripheral alkyl chains of triphenylene influenced properties of liquid crystal dimers; dimers 3(n) (n = 5-8) and 6 had glass columnar phase, and no crystallization was observed above −50℃ for all the triphenylene dimers; compared with 3(6), 6 showed higher molecular symmetry, more stable columnar mesophase and wider mesophase range. The connecting group, length and rigidity of spacer had important influence on the mesomorphism of diacetylene-bridged triphenylene discotic liquid crystal dimers.triphenylene, discotic liquid crystal, Eglinton coupling reaction, liquid crystal dimer, glass columnar phase Liquid crystal dimers are a type of molecule which contain two identical or different mesogenic groups linked via a spacer. Their physical properties are different from those of conventional low molecular mass liquid crystals. They show a variety of mesophases [1][2][3][4][5][6] and some of liquid crystal dimers display properties of polymers, such as glass transition behavior [7][8][9] . So they can serve as ideal model compounds in liquid crystal polymer investigation and have received considerable attention. Rod-like liquid crystal dimers have been well studied and their structure-property relationships have been elucidated [10] . By contrast, discotic liquid crystals (DLCs) have comparatively short history. Thus, further exploration of the synthesis, characterization and structure-property relationships of DLC dimers, oligomers and polymers is necessary.Triphenylene derivatives are important family members of DLCs. They can self-assemble into highly ordered hexagonal columnar (Col ho ) mesophase and possess high mobility of charges and energy [11] . Moreover, triphenylene DLCs can be easily synthesized and purified, showing plenty of structural variation and fine thermal and chemical stability [12,13] . They have been applied as one-dimensional conductors [14] , photoconductors [15] , and light-emitting diodes [16] . In recent years, triphenylene DLC dimers, oligomers and polymers have attracted increasing attention [17][18][19][20][21][22][23][24] . The dynamics of discogens, such as rotation around the column axes, fluctuation in the column, and slippage out of column, has been partially inhibited by connecting two triphenylene mesogens via a spacer. Thus, the dimers show more ordered and stable Col mesophase and im-

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“…Polarizing microscopy: Olympus BX50 polarizing microscope combined with a Linkam LTS350 hot stage and Linkam TP 93 central processor. (3R)-1,2-Bis(3,7-dimethyloctyloxy)benzene (5a) was prepared according to [13], (3R)-1-bromo-3,7-dimethyloctane was prepared according to [14], and 2-hydroxy-3,6,7,10,11-pentakis(decyloxy)triphenylene (1) was prepared according to [10].…”

Section: Experimental Partmentioning

confidence: 99%

“…FeCl 3 -Mediated cyclization of 1,1'-biphenyl 6 and gujacol derivative 7 to 8 proceeded in 51% yield. With regard to the yield, this coupling was found advantageous compared to the direct coupling of 1,2-dialkyloxybenzene 5a with 7 [10]. Final condensation of the achiral building block 4c with the chiral subunit 8 in the presence of K 2 CO 3 provided the desired twin 9 in 64% yield.…”

mentioning

confidence: 98%

“…± For the synthesis of 9, a convergent strategy was used, in which the chiral triphenylene moiety 8 was attached to the tether carrying achiral triphenylene 4c in the final step. Thus, decane-1,10-diol (2) was converted to the 3,4,5,6-tetrahydro-2H-pyran-2-yl(Thp)-protected bromo derivative 3, which was further coupled with achiral hydroxytriphenylene 1 [10] to give 4a in 90% yield. Deprotection and bromination of the primary OH group yielded 4c.…”

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confidence: 99%

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Combination of Chiral and Achiral Triphenylene Units in a Novel Unsymmetrical Columnar Twin

Hirst¹,

Diele²,

Nimtz

2001

HCA

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The synthesis, characterization, and mesomorphic properties of a new type of liquid-crystalline twin bearing a pentadecyloxytriphenylene subunit tethered via a decyl spacer to a chiral pentakis(3,7-dimethyloctyloxy)-triphenylene are reported. The target compound displays a hexagonal columnar mesophase, which is metastable at room temperature.Introduction. ± Among the two major classes of thermotropic liquid crystals, i.e., calamitic (rod-shaped) and discotic (disk-shaped) liquid crystals, the latter type, which forms columnar short-range-ordered assemblies in the mesophase, has attracted many researchers during the last decade [1] [2]. The interest in discotic liquid crystals is mainly due to their promising physical properties, such as electrical and photoconductivity, and high charge-carrier mobility along the columns [3]. From this work, the so-called columnar twins or oligomers have emerged recently, constituting two or more discotic subunits connected to each other by a flexible spacer [4]. 2,3,6,7,10,11-Hexasubstituted triphenylenes are ideally suited building blocks for columar liquid crystals, and many examples of both symmetrical and unsymmetrical twins based on triphenylenes are known (for recent examples, see [5]). However, only few polymeric liquid crystals and columnar twins containing chiral triphenylenes have been published so far (for chiral polymeric triphenylenes, see [6]; for chiral monomeric triphenylenes, see [7]). Particularly attractive to us seemed unsymmetrical twins bearing chiral and achiral moieties of similar sizes, because these twins might be able to form different chiral and achiral microdomains within a columnar mesophase. The presence of chiral subunits might induce helical twisting of the columns, which is a prerequisite for ferroelectricity [8]. Those unsymmetrical dimers may either retain the mesomorphic properties of the subunits by columnar stacking of like subunits, or form supramolecular aggregates by columnar stacking of unlike subunits and thus display novel mesomorphic properties. As shown in Fig. 1, four different orientations are conceivable, i.e., a) formation of two-dimensional domains within one lattice sheet, b) an intracolumnar regular ordered pattern, with the chiral and achiral subunits being segregated in different columns, c) an intracolumnar regular mixed pattern, with chiral and achiral subunits of neighboring twins stacked alternatively within the columns, and d) an intracolumnar randomly mixed pattern [9]. The micro-segregation in a ± c should lead to different mesomorphic properties, e.g., increased phase stability, as compared to

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Convergent Synthesis of Columnar Twins and Tetramers from Triphenylene Building Blocks – The First Example of a Columnar Spiro-Twin

Cited by 58 publications

References 34 publications

Columnar Liquid Crystals with a Central Crown Ether Unit

Columnar Liquid Crystals with a Central Crown Ether Unit

Synthesis and mesomorphism of diacetylene-bridged triphenylene discotic liquid crystal dimers

Combination of Chiral and Achiral Triphenylene Units in a Novel Unsymmetrical Columnar Twin

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