Chiral columns forming a lattice with a giant unit cell

Rybak, Paulina; Krówczyński, Adam; Szydłowska, Jadwiga; Pociecha, Damian; Górecka, Ewa

doi:10.1039/d1sm01585k

Cited by 6 publications

(10 citation statements)

References 40 publications

(40 reference statements)

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“…The appearance of the highly ordered yet noncrystalline Fddd phase confirmed that the chirality of close-packed twisted ridged (i.e., noncircular) columns, without any junctions, can indeed be maintained over a long range. Subsequently, the Fddd phase was also found in a compound with an -shape core, one-ring wide in the middle and two-ring wide at each end . Our preliminary studies also suggest that this phase and its variants may be widespread in polycatenars, including those formed by hydrogen-bonded half-rods and in side-chain LC polymers.…”

Section: Introductionsupporting

confidence: 56%

“…Subsequently, the Fddd phase was also found in a compound with an I-shape core, one-ring wide in the middle and two-ring wide at each end. 44 Our preliminary studies also suggest that this phase and its variants may be widespread in polycatenars, including those formed by hydrogen-bonded half-rods and in side-chain LC polymers. It would also not be surprising if it was found in compounds with 3-arm star molecules of C 3 symmetry that also form a columnar phase at higher temperatures.…”

Section: Introductionmentioning

confidence: 57%

“…We now consider the reason why only the RS mixtures form the Fddd phase, while neither the pure enantiomers nor the nonchiral N–C10 form it. In comparison, all compounds reported so far to form the Fddd were achiral. , For this purpose, we consider the energy barriers for rotation around single bonds within the mesogen core. Three bonds were examined: (1) the C–C bond between the benzene ring and the ester group in the benzoate, i.e., the rotation angle marked α 1 in Figure S14, (2) the C–O bond between the ester group and the biphenyl, torsion angle α 2 , and (3) the C–O bond of the butanoate (in chiral enantiomers) or propionate (in the nonchiral N–C10 ), angle α 3 , Figure a,b.…”

Section: Resultsmentioning

confidence: 99%

“…Other achiral compounds, without the flexible linkage, do form the Fddd phase below the Col h . 21,44 The twisted ribbons in Fddd, with a 7.54 nm pitch, consist of stacked rafts, each containing ∼2 side-by-side molecules, the successive rafts rotated by 17°. Regarding the Col h phase, ultrafast flash DSC cooling scans show that its formation from the melt is extremely fast, completing in ∼20 ms.…”

Section: Discussionmentioning

confidence: 99%

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Enantiomers Self-Sort into Separate Counter-Twisted Ribbons of the Fddd Liquid Crystal─Antiferrochirality and Parachirality

Wang,

Li,

Cseh

et al. 2023

J. Am. Chem. Soc.

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The recently discovered orthorhombic liquid crystal (LC) phase of symmetry Fddd is proving to be widespread. In this work, a chiral hydroxybutyrate linkage is inserted into the molecular core of hexacatenar rodlike compounds, containing a thienylfluorenone fluorophore. In addition to more usual tools, the methods used include grazing-incidence X-ray scattering, modulated differential scanning calorimetry (DSC), flash DSC with rates up to 6000 K/s, and chiro-optical spectroscopies using Mueller matrix method, plus conformational mapping. Although pure R and S enantiomers form only a strongly chiral hexagonal columnar LC phase (Col h *), the racemic mixture forms a highly ordered Fddd phase with 4 right-and 4 left-handed twisted ribbon-like columns traversing its large unit cell. In that structure, the two enantiomers locally deracemize and self-sort into the columns of their preferred chirality. The twisted ribbons in Fddd, with a 7.54 nm pitch, consist of stacked rafts, each containing ∼2 side-by-side molecules, the successive rafts rotated by 17°. In contrast, an analogous achiral compound forms only the columnar phase. The multiple methods used gave a comprehensive picture and helped in-depth understanding not only of the Fddd phase but also of the "parachiral" Col h * in pure enantiomers with irregular helicity, whose chirality is compared to the magnetization of a paramagnet in a field. Unusual short-range ordering effects are also described. An explanation of these phenomena is proposed based on conformational analysis. Surprisingly, the isotropic−columnar transition is extremely fast, completing within ∼20 ms. A clear effect of phase on UV−vis absorption and emission is observed.

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Section: Introductionsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Enantiomers Self-Sort into Separate Counter-Twisted Ribbons of the Fddd Liquid Crystal─Antiferrochirality and Parachirality

Wang,

Li,

Cseh

et al. 2023

J. Am. Chem. Soc.

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“…[ 25 ] Recently, Rybak et al reported quinoxaline derivatives with semiflexible cores stabilizing Col mesomorphism. [ 36 ] All the above said works motivated us to try the new possibility of combining carbazole units with pyrazino[2,3‐g]quinoxaline central core.…”

Section: Introductionmentioning

confidence: 99%

A New Class of Solution Processable Pyrazino[2,3‐g]quinoxaline Carbazole Derivative Based on D–A–D Architecture for Achieving High EQE in Yellow and White OLEDs

Vishwakarma

Nagar

Lhouvum

et al. 2022

Advanced Optical Materials

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level. Carbazole-containing polymers were used as organic light-emitting diodes, [1][2][3] photovoltaic cells, [4,5] and thin-film transistors. [6,7] They have also found application in electrochromic devices as they can form relatively stable cations on the application of voltage. [8,9] Carbazole-based compounds also found application in the synthesis of several thermally activated delayed fluorescence (TADF) materials, which are capable of enhancing the emission efficiency of present-day organic light-emitting diodes (OLEDs) by harvesting the excitons in a triplet state. [10,11] However, the realization of such beneficial materials requires the proper combination of carbazoles with suitable acceptor units with a twisted structure with a reduced energy gap between the singlet and triplet states. Carbazoles are also utilized as donor units in donor-acceptor (D-A) compounds with a high potential for synthetic tunability, ambipolar charge transport, and light-emitting materials with high emission efficiency. [12][13][14][15] A wide variety of carbazole derivatives are used in fluorescent and phosphorescent OLEDs due to their suitable energy levels, good charge transport behavior, and high triplet energies as host materials. [16][17][18][19][20][21] Being an inexpensive, stable starting material with the ease of functionalization by N-alkylation and core modification, carbazole provides enormous opportunities for structural modifications to realize functional materials. [22] Quinoxaline derivatives also have been used in organic electronic devices like organic solar cells, [23,24] OLEDs, [25] and organic field effect transistors (OFETs). [26] They have also found application in the construction of supramolecular self-assembling materials, [27] sensors, [28] and also as acceptor units in the building of D-A systems with low energy gaps. [29] Pei and co-workers developed tetrasubstituted pyrazino[2,3g]quinoxaline derivatives with thiophene and phenyl rings, which leads to varying extent of conjugation to achieve highefficiency active waveguide fibers. [30] Grimsdale and co-workers further extended the conjugation and introduced substituents at the quinoidal positions to study the electronic properties of the pyrazino[2,3-g]quinoxaline derivatives. [31] A water-soluble pyrazino [2,3-g]quinoxaline based photosensitizer reported by A new pyrazino[2,3-g]quinoxaline carbazole derivative with branched alkyl peripheral chains PQC-12b with a donor-acceptor-donor nonplanar architecture is reported. PQC-12b exhibits high molar extinction coefficients, low bandgap, bright emission behavior in solution and solid-state, along with positive solvatochromism. PQC-12b is used in organic light-emitting diodes (OLEDs) either as sole emissive material or as a guest in different host materials. Amongst these different host-guest OLEDs, CBP-based device with the optimized concentration of PQC-12b shows maximum values for power efficacy (PE max ) of 14.1 lm W −1 , current efficacy of 26.8 cd A −1 , external quantum efficiency (EQE max ) of ...

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Supertwisted Chiral Gyroid Mesophase in Chiral Rod‐Like Compounds

Wang,

Yang,

et al. 2024

Angewandte Chemie

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Among the intriguing bicontinuous self‐assembled structures, the gyroid cubic is the most ubiquitous. It is found in block and star polymers, surfactants with or without solvent, in thermotropic liquid crystals with end‐ or side‐chains, and in biosystems providing structural color and modelling cell mitosis. It contains two interpenetrating networks of opposite chirality and is thus achiral if, as usual, the content of the two nets is the same. But we now find that this is not the case for strongly chiral compounds. While achiral molecules follow the opposite twists of nets 1 and 2, molecules with a chiral center in their rod‐like core fail to follow the 70° twist between junctions in net 2 and instead wind against it by ‐110° to still match the junction orientation. The metastable chiral gyroid is a high‐entropy high‐heat‐capacity mesophase. The homochirality of its nets makes the CD signal of the thienofluorenone compounds close to that in the stable I23 phase with 3 isochiral nets.

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Chiral columns forming a lattice with a giant unit cell

Abstract: Mesogenic materials, quinoxaline derivatives with semi-flexible cores, are reported to form new type of 3D columnar structure with large crystallographic unit cell and Fddd lattice below columnar hexagonal phase. The...

Cited by 6 publications

References 40 publications

Enantiomers Self-Sort into Separate Counter-Twisted Ribbons of the Fddd Liquid Crystal─Antiferrochirality and Parachirality

Enantiomers Self-Sort into Separate Counter-Twisted Ribbons of the Fddd Liquid Crystal─Antiferrochirality and Parachirality

A New Class of Solution Processable Pyrazino[2,3‐g]quinoxaline Carbazole Derivative Based on D–A–D Architecture for Achieving High EQE in Yellow and White OLEDs

Supertwisted Chiral Gyroid Mesophase in Chiral Rod‐Like Compounds

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