Columnar propeller-like 1,3,5-triphenylbenzenes: the missing link of shape-persistent hekates

Wöhrle, Tobias; Beardsworth, Stuart J.; Schilling, Chris; Baro, Angelika; Gießelmann, Frank

doi:10.1039/c5sm02489g

Cited by 30 publications

(35 citation statements)

References 48 publications

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“…TDPB ’s triphenylbenzene core gives it the potential to act as a discotic mesogen 43. Although TDPB is not able to form mesophases on its own due to the lack of soft and flexible peripheral alkyl groups, such groups can be introduced through doping.…”

Section: Resultsmentioning

confidence: 99%

Exploring Redox States, Doping and Ordering of Electroactive Star‐Shaped Oligo(aniline)s

Mills

Fey

Marszałek

et al. 2016

Chemistry A European J

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We have prepared a simple star‐shaped oligo(aniline) (TDPB) and characterised it in detail by MALDI‐TOF MS, UV/Vis/NIR spectroscopy, time‐dependent DFT, cyclic voltammetry and EPR spectroscopy. TDPB is part of an underdeveloped class of π‐conjugated molecules with great potential for organic electronics, display and sensor applications. It is redox active and reacts with acids to form radical cations. Acid‐doped TDPB shows behaviour similar to discotic liquid crystals, with X‐ray scattering investigations revealing columnar self‐assembled arrays. The combination of unpaired electrons and supramolecular stacking suggests that star‐shaped oligo(aniline)s like TDPB have the potential to form conducting nanowires and organic magnetic materials.

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Section: Resultsmentioning

confidence: 99%

Exploring Redox States, Doping and Ordering of Electroactive Star‐Shaped Oligo(aniline)s

Mills

Fey

Marszałek

et al. 2016

Chemistry A European J

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“…Herein, we report on the self‐assembling features of a series of 1,3,5‐triphenylbenzenetricarboxamides (TPBAs) endowed with achiral ( 1 ) or chiral ( ( S )‐2 and ( R )‐3 ) paraffinic side chains (Figure a). At the molecular level, the restricted rotation of the benzamide units would afford a propeller‐like configuration and, consequently, the generation of the M and P atropisomers (Figure b) . Experimental and theoretical evidences demonstrate that the cooperative supramolecular polymerization of 1 – 3 produces helical columnar stacks in which the molecular atropisomerism is cancelled (Figure c).…”

Section: Figurementioning

confidence: 99%

Hierarchy of Asymmetry at Work: Chain‐Dependent Helix‐to‐Helix Interactions in Supramolecular Polymers

Díaz-Cabrera¹,

Dorca²,

Calbo

et al. 2018

Chemistry A European J

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A detailed investigation of the hierarchy of asymmetry operating in the self-assembly of achiral (1) and chiral ((S)-2 and (R)-3) 1,3,5-triphenylbenzenetricarboxamides (TPBAs) is reported. The aggregation of these TPBAs is conditioned by the point chirality at the peripheral side chains for (S)-2 and (R)-3. An efficient helix-to-helix interaction that goes further in the organization of fibrillar bundles is experimentally detected and theoretically supported only for the achiral TPBA 1. The effective interdigitation of the achiral aliphatic side chains produces a social self-sorting to form preferentially heterochiral macromolecular aggregates.

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“…In previous work on tris(trialkoxyphenyl)benzenes 4 the methoxy group was reported to serve as a minimalistic alkoxy unit at the outer phenyl rings, resulting in decreased clearing temperature while keeping the stable columnar mesophase . Motivated by this observation we surmised that omission or successive replacement of alkoxy side chains by chloro substituents might affect the phase behaviour in a similar fashion.…”

Section: Introductionmentioning

confidence: 89%

“…The archetypal discotic liquid crystal contains a central rigid aromatic or heteroaromatic core surrounded by peripheral flexible chains, which self‐assembles into columnar mesophases due to π–π interactions of the core, while the chains stabilize the columnar phase through van der Waals interactions and suppress crystallization due to their flexibility, These self‐assembled structures are interesting because their 1D charge carrier mobility and self‐healing of defects make them suitable for molecular electronics applications , . However, long alkoxy side chains can cause synthetic challenges (e.g., purification and solubility) and furthermore, limit applications by clearing points close to the thermal decomposition temperature , . Thus, discotic liquid crystals where peripheral alkoxy chains have been replaced by some surrogate would be highly attractive.…”

Section: Introductionmentioning

confidence: 99%

“…Star‐shaped 1,3,5‐triphenylbenzenes such as 4 (Scheme ) belong to the class of shape‐persistent hekates which are able to form columnar mesophases . Space‐filling between the three arms is achieved either by helical twisting along the columnar axis or by incorporation of bulky guest molecules covalently or non‐covalently bound to the star, giving rise to unique self‐assembled structures , …”

Section: Introductionmentioning

confidence: 99%

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Columnar Propeller‐Like 1,3,5‐Triphenylbenzenes: Probing the Effect of Chlorine on the Suzuki Cross‐Coupling and Liquid Crystalline Properties

et al. 2020

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Suzuki cross-couplings either between chlorinated N-methyliminodiacetic acid (MIDA)-protected aryl boronates and 1,3,5-tribromobenzene or between chlorinated aryl bromides and phenyltrisboronic species to star-shaped 1,3,5-triphenylbenzenes with different substitution patterns and chloro substituents at the outer phenyl rings were studied. The chlorinated precursors required for the respective reaction were synthesized and characterized. Depending on the used coupling reaction target triphenylbenzenes were isolated in yields between 42 % and 88 %. Their mesomorphic properties were in- [a] 2190 fluenced by the substitution pattern and number of peripheral chlorine atoms. Triphenylbenzene with 3,5-alkoxy substitution and H in para-position self-assembled into either columnar hexagonal (Col h ) mesophases or a soft crystal. While threefold chloro substitution in meta-position of the outer phenyl rings led to stable room temperature Col ho phases, triphenylbenzenes with threefold para-chloro or 3,5-dichloro substitution were non-mesomorphic. Based on X-ray diffraction data a helical packing model for the observed phases similar to that of related alkoxy-substituted triphenylbenzenes was proposed.properties and a decrease of phase transition temperatures were independently reported for bent-core liquid crystals by Twieg [9,10] and for ionic liquid crystals by Binnemans. [11] Scheme 1. Selected liquid crystalline pseudoazulenes (1, 2) and indene derivative 3. [7,8] Scheme 2. dated. To study the effects in more detail, convenient synthetic access to (poly)chlorinated triphenylbenzenes 5 is required. In contrast to the plethora of well-explored Suzuki-Miyaura crosscoupling of aryl halides with aryl boron species, [21][22][23][24][25] the use of di-and poly-chlorinated reactants has been mostly devoted to access polychlorinated biphenyl (PCB) derivatives for ecotoxicity and analytical property studies. [26][27][28][29][30][31][32][33] In order to get access to triphenylbenzenes 5 we followed two synthetic strategies involving a cross-coupling as the key step (Scheme 3). Compound 5 is derived either from Suzuki-Miyaura cross-coupling between aryl boronic species 6 [e.g., N-methyliminodiacetic acid (MIDA) boronates [34][35][36][37][38][39] ] and 1,3,5-tribromobenzene 7 (route A) or alternatively, by the connection of aryl bromides 8 and 1,3,5-phenyltrisboronic species 9 (e.g., pinacol boronate) (route B). The results towards the synthesis of compounds 5 and study of their mesomorphic properties are reported below. Scheme 4. Synthesis of precursors 6 and 8 (numbering for NMR assignment; for details see also the Supporting Information). 2191Scheme 3. Retrosynthetic pathways to star-shaped triphenylbenzenes 5.

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Columnar propeller-like 1,3,5-triphenylbenzenes: the missing link of shape-persistent hekates

Abstract: Triphenylbenzenes with nine peripheraln-alkoxy side chains form enantiotropic, highly ordered columnar hexagonal mesophases near room temperature. Wide-angle X-ray data indicate a helical stacking in columns.

Cited by 30 publications

References 48 publications

Exploring Redox States, Doping and Ordering of Electroactive Star‐Shaped Oligo(aniline)s

Exploring Redox States, Doping and Ordering of Electroactive Star‐Shaped Oligo(aniline)s

Hierarchy of Asymmetry at Work: Chain‐Dependent Helix‐to‐Helix Interactions in Supramolecular Polymers

Columnar Propeller‐Like 1,3,5‐Triphenylbenzenes: Probing the Effect of Chlorine on the Suzuki Cross‐Coupling and Liquid Crystalline Properties

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