Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals

• Alessandro L. Alves,
• Simone V. Bernardino,
• Carlos H. Stadtlober,
• Edivandro Girotto,
• Giliandro Farias,
• Rodney M. do Nascimento,
• Sergio F. Curcio,
• Thiago Cazati,
• Marta E. R. Dotto,
• Juliana Eccher,
• Leonardo N. Furini,
• Hugo Gallardo,
• Harald Bock and
• Ivan H. Bechtold

Beilstein J. Org. Chem. 2023, 19, 1755–1765, doi:10.3762/bjoc.19.128

• molecular π-stacking inside the columns. The pyrene crystallizes bellow 166 °C, preserving the close-packed columnar rectangular structure of the mesophase. Photophysical analysis and numerical calculations assisted the interpretation of positive and negative charge carrier mobilities obtained from fitting

• ) obtained is 23.7 Å for 1 and 22.9 Å for 2. The a/b aspect ratio of the Colrect phase of 2 is equal to 2.08, representing an elongation of around 20% concerning the hexagonal mesophase (where a/b = 1.73). The π-stacking distance between neighboring disks inside the columns, indicated by the (001) peak, is

• columnar hexagonal mesophase stable at room temperature, and compound 2 is pyrene-based crystalline with columnar rectangular order preserved at room temperature. Photoluminescence lifetime measurements indicated that molecular aggregation and π-stacking interactions dominate the photophysics of films

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• generation of waste or the use of environmentally friendly conditions, and they also allow recycling catalysts without losing efficiency [67][68][70]. Kholdeeva and co-workers reported the use of 30% aqueous H2O2 as oxidant and hydrothermally stable mesoporous mesophase titanium silicates (Ti-MMM-2) as

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• azopyridines with molecular iodine or bromine [9]. Interestingly, the broadest mesophase temperature ranges were found for the bromine-based assemblies and not as anticipated, for the iodine system which yields a stronger halogen bond. In order to prove that the halogen bond plays a crucial role for the

• segments, which is crucial for the formation of a mesophase [7][20]. The azo compounds with a weakly polarised iodine atom (F2Az or F2’Az) have significantly lower interaction energies and halogen bonding appears not sufficiently strong enough to extend the mesogenic core at elevated temperatures. Thus, no

• induce liquid crystallinity (see Figure 6) [12]. It appears surprising, that NO2-C10∙∙∙F3Az shows a broader nematic mesophase range (ΔT = 12.5 °C) than NO2-C10∙∙∙F4Az (ΔT = 4.6 °C). However, the increase in the temperature range is predominantly attributed to the lowering of the crystallisation

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• . Thiourea and amide derivatives were predominantly SmA mesophase inductors. A nematic mesophase was observed only for thioureas and amides containing an isoxazole ring. Additionaly, the liquid crystal behavior was also dependent on the relative position of nitrogen and oxygen atoms on the 5-membered

• behavior. A smectic A mesophase (SmA) was preponderant in this study. However, a nematic mesophase (N) appeared for thioureas 18a and 18c and amide 20. Thioureas 17b, 18b and 18c and amides 19, 20, 22 and 24 displayed an enantiotropic SmA mesophase, except thiourea 17a which showed a monotropic SmA

• mesophase. A monotropic smectic C mesophase (SmC) at 198 °C was observed for amide 19. Perfluorinated thioureas 17b and 18b presented an SmA mesophase, independent of the nature of the 5-membered heterocycle. The perfluorinated alkyl chain in both compounds is the reason of preference for a lamellar SmA

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

• Afef Mabrouki,
• Malek Fouzai,
• Armand Soldera,
• Abdelkader Kriaa and
• Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

• the fluorine atom leads to a subtle modification of properties such as melting point, mesophase morphology, transition temperatures, optical anisotropy, dielectric anisotropy, and visco-elasticity [5][6][7][8][9][10]. Therefore, many fluorinated liquid crystals have been prepared, and the fluoro

• the presence of monotropic intermediate phase between T = 115.8 °C and T = 125.1 °C [30]. As it can be seen in the thermogram of compound 4a, the monotropic liquid crystal mesophase is observed in cooling between T = 91.6 °C and 98.9 °C. Concerning compound 4b, the thermogram shows an enantiotropic

• stability of the compound. Based on the texture in Figure 2d, we can note that the mesophase is hexagonal SmB with strongly double refracting lancets and regions [31]. Under crossed polarizes, compound 2d is not capable to induce any liquid crystalline behaviour, they present only crystal phases. Gallardo

Syntheses of dibenzo[d,d']benzo[2,1-b:3,4-b']difuran derivatives and their application to organic field-effect transistors

• Minh Anh Truong and
• Koji Nakano

Beilstein J. Org. Chem. 2016, 12, 805–812, doi:10.3762/bjoc.12.79

• mesophase of syn-DBBDF 5 was converted to the isotropic phase at 115 °C, while syn-DNBDF 6 did not melt below 250 °C. From the TG measurement, the temperatures of 5% weight loss (Td5) of syn-DBBDF 5 and syn-DNBDF 6 were estimated to be 272 °C and 423 °C, respectively (Figure 2b). Photophysical properties

Synthesis of photoresponsive cholesterol-based azobenzene organogels: dependence on different spacer lengths

• Yuchun Ren,
• Bin Wang and
• Xiuqing Zhang

Beilstein J. Org. Chem. 2015, 11, 1089–1095, doi:10.3762/bjoc.11.122

• mesophase transition and mesophase to isotropic transition. On the cooling run, DSC curves presented isotropic phase to mesophase, mesophase to crystal and crystal to crystal at 190, 155 and 126 °C. Each curve of compounds M2, M6 and M10 displayed a single endothermic melting peak. The heating DSC curves of

• M3, M5 and M12 contained two endothermic peaks. The peaks at lower temperature were due to the crystal to mesophase transitions, and the second peaks displayed the mesophase to isotropic transitions. The DSC thermogram of M3, M5 and M12 were observed two exothermic peaks on cooling process, which

• indicated the transitions from isotropic phase to mesophase at higher temperature and mesophase to crystal transitions at lower temperature Gelation behaviors The gelation behaviors of the seven compounds were tested in 22 solvents at room temperature and the results were listed in Table 2. Among the

Novel biphenyl-substituted 1,2,4-oxadiazole ferroelectric liquid crystals: synthesis and characterization

• Mahabaleshwara Subrao,
• Dakshina Murthy Potukuchi,
• Girish Sharada Ramachandra,
• Poornima Bhagavath,
• Sangeetha G. Bhat and
• Srinivasulu Maddasani

Beilstein J. Org. Chem. 2015, 11, 233–241, doi:10.3762/bjoc.11.26

• *Cn) series contain a rigid phenyl moiety on one side and a flexible alkyl chain on the other side of the oxadiazole central core. They are found to exhibit a 1D orthogonal SmA mesophase only. Further, the mesomorphic thermal range is not appreciably changing with increasing the chain length (Figure 5

• biphenyl moiety by Suzuki coupling reaction. Both the series of compounds have the same molecular skeleton except the end group on one side of the central core. The series with the bulky phenyl end group on one side of the oxadiazole core is found to exhibit a 1D orthogonal SmA mesophase only whereas the

• other series with flexible alkyl end chain are found to exhibit chiral SmC phase along with the SmA mesophase. The compounds with flexible end chains on both sides (13b or C12.Ox.C*Cn) of the oxadiazole core are found to exhibit a higher mesomorphic thermal range than the series with a phenyl end group

The influence of intraannular templates on the liquid crystallinity of shape-persistent macrocycles

• Joscha Vollmeyer,
• Ute Baumeister and
• Sigurd Höger

Beilstein J. Org. Chem. 2014, 10, 910–920, doi:10.3762/bjoc.10.89

• substituents influence the thermal stability of the gel. As pointed out before, the ring interior can also have a dramatic effect on the mesophase stability of thermotropic liquid crystalline shape-persistent macrocycles [40][43][44][45]. However, more detailed studies on that issue are still scarcely found in

• compound melts isotropically and does not exhibit a mesophase [47]. By comparing the macrocycles 1a, 2a, 3a, and 4a, all with the same intraannular alkyl template the melting points decrease with increasing length of the extraannular alkyl chains. The lowest transition temperature is observed for 1a, with

• observed upon the second heating indicating crystallization and melting during the experiment. Clear hints on a stable mesophase could be obtained neither for 1b nor for 1c. From the DSC it seems that also 1c exhibits an lc phase between 89 °C and 105 °C. However, from the POM and X-ray data we assume that

Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core

• Anna Kovářová,
• Svatopluk Světlík,
• Václav Kozmík,
• Jiří Svoboda,
• Vladimíra Novotná,
• Damian Pociecha,
• Ewa Gorecka and
• Natalia Podoliak

Beilstein J. Org. Chem. 2014, 10, 794–807, doi:10.3762/bjoc.10.75

• cyano end-capped bent-shaped materials it was documented [29][30][31] that reversing the position of hydroxylic and carboxylic groups exerts a profound effect on the mesophase properties. The bent-shaped molecules can create polar mesophases in spite of lack of molecular chirality. The most frequently

• paper we present results obtained for new bent-shaped mesogens based on thehydroxybiphenylcarboxylic core. We emphasize the complexity of the mesophase behavior and present a new phase sequence with a reentrancy of the SmCP phase. Additionally, the 2D modulated phase with local ‘general tilt’ structure

• ], the type of mesophase depends on the orientation of the ester linkage group as well as on the length and character of the terminal chains. All compounds of series I exhibit the SmCAPA phase with typical textures and behavior in the electric field. Reversing the orientation of one ester group

Triphenylene discotic liquid crystal trimers synthesized by Co₂(CO)₈-catalyzed terminal alkyne [2 + 2 + 2] cycloaddition

• Bin Han,
• Ping Hu,
• Bi-Qin Wang,
• Carl Redshaw and
• Ke-Qing Zhao

Beilstein J. Org. Chem. 2013, 9, 2852–2861, doi:10.3762/bjoc.9.321

• exhibited a rectangular columnar mesophase, while 5b and 5c possessing an ether linkage and a shorter spacer display a hexagonal columnar mesophase. The connecting functional group and the length of the flexible spacer between the central benzene ring and the triphenylene units have pivotal influence on the

• mesomorphism. Keywords: Co2(CO)8 catalyzed cycloaddition; columnar mesophase; discotic liquid crystal; triphenylene; oligomer; Introduction Discotic liquid crystals (DLCs) with nematic phase have been commercially utilized in the liquid crystal display industry as optical compensating films for widening the

• construction methods for the oligomers. However, DLC oligomers usually possess wider mesophase ranges than the monomers as the crystallization was prevented, due to the size of molecules is enlarged and molecular symmetry is lowered. However DLC oligomers exhibit higher charged carrier mobility than DLC

Synthesis of guanidinium–sulfonimide ion pairs: towards novel ionic liquid crystals

• Martin Butschies,
• Manuel M. Neidhardt,
• Markus Mansueto,
• Sabine Laschat and
• Stefan Tussetschläger

Beilstein J. Org. Chem. 2013, 9, 1093–1101, doi:10.3762/bjoc.9.121

• anions and imidazolium cations with short alkyl chains were studied by DesMarteau resulting in room-temperature ionic liquids [21]. In contrast, ILCs with bistriflimide anions are much less explored, because the sterically demanding anion often inhibits the formation of a mesophase [6][22]. Liquid

• complementary ion pairs, where guanidinium sulfonate 1 with both mesogenic cation and anion displayed improved mesophase stability and increased phase widths as compared to their counterparts bearing a nonmesogenic spherical halide counterion [38][39] (Scheme 1). We were thus interested, whether this concept

• ∙I, the formation of a smectic mesophase was completely suppressed. For protonated guanidinium sulfonimides 3a,b again a significant decrease of the melting temperature was found (75 °C and 71 °C, respectively, Table 1, entries 4 and 5) as compared to the protonated guanidinium iodide 7∙I, which

Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

• Alexej Bubnov,
• Miroslav Kašpar,
• Věra Hamplová,
• Ute Dawin and
• Frank Giesselmann

Beilstein J. Org. Chem. 2013, 9, 425–436, doi:10.3762/bjoc.9.45

• systems composed of amphiphilic molecules can exhibit smectic phases with layered structure [2] or nematic (eventually cholesteric) phases. Lyotropic systems usually form a lamellar liquid-crystalline mesophase, i.e., a lyotropic analogue of the thermotropic orthogonal smectic A (SmA) phase [3], and more

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

A new family of four-ring bent-core nematic liquid crystals with highly polar transverse and end groups

• Kalpana Upadhyaya,
• Venkatesh Gude,
• Golam Mohiuddin and
• Rao V. S. Nandiraju

Beilstein J. Org. Chem. 2013, 9, 26–35, doi:10.3762/bjoc.9.4

• exhibited monotropic nematic phases, while compounds with lateral and terminal polar substituents did not show mesomorphism. A preliminary insight into the structure–property relationships of bent-core molecules revealed that the mesophase behaviour is strongly influenced by the number of rings [21][22][35

Formation of smectic phases in binary liquid crystal mixtures with a huge length ratio

• Nadia Kapernaum,
• Friederike Knecht,
• C. Scott Hartley,
• Jeffrey C. Roberts,
• Robert P. Lemieux and
• Frank Giesselmann

Beilstein J. Org. Chem. 2012, 8, 1118–1125, doi:10.3762/bjoc.8.124

• the SmC phase, which was the dominant phase in most of the pure compounds, was reduced while the SmA phase became broader. In the systems with a length ratio of 1.8, the smectic A phase was the only stable mesophase over a broad temperature and concentration range. Furthermore, a decrease of the tilt

Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit

• Govindaswamy Shanker,
• Marko Prehm and
• Carsten Tschierske

Beilstein J. Org. Chem. 2012, 8, 472–485, doi:10.3762/bjoc.8.54

• of a uniaxial mesophase, but surprisingly, no enthalpy change is associated with this transition as observed in the DSC traces (Figure 2a). Similar features can be observed for the shorter homologue CB-Ox/3 (see Table 1). XRD patterns of the nematic phase of compound CB-Ox/4, obtained with a

Perhydroazulene-based liquid-crystalline materials with smectic phases

• Zakir Hussain,
• Henning Hopf and
• S. Holger Eichhorn

Beilstein J. Org. Chem. 2012, 8, 403–410, doi:10.3762/bjoc.8.44

• formulation of various components, including about 15–20 individual LC molecules. The nematic (N) liquid crystal phase, with its orientational order only, is the most important mesophase; it is used in almost all commercially available LC displays. On the other hand, the smectic (Sm) LC phases, with their

• introduce terminal chains, they can provide flexibility to stabilize the molecular alignment within the mesophase. Such terminal chains can either be nonpolar straight alkyl chains or carry a polar substituent. Such molecules may form both nematic and smectic mesophases depending upon the type of

• to 8b. This mesophase was stable up to 244 °C at which it converted into a short-range SmA phase followed by transitions into the nematic and isotropic phases at 253 °C and 266 °C, respectively. Appearance of transitions at much higher temperatures in case of 10b compared to 8b could be associated

Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

• Katharina C. Kress,
• Martin Kaller,
• Kirill V. Axenov,
• Stefan Tussetschläger and
• Sabine Laschat

Beilstein J. Org. Chem. 2012, 8, 371–378, doi:10.3762/bjoc.8.40

• 13b upon cooling from the isotropic liquid. Due to supercooling, no crystallisation could be observed for compound 11a and, therefore, no mesophase range could be determined. But the second and third heating runs of 11a showed broad recrystallization peaks (Figure 2). Polarizing optical microscope

Liquid-crystalline nanoparticles: Hybrid design and mesophase structures

• Gareth L. Nealon,
• Romain Greget,
• Cristina Dominguez,
• Zsuzsanna T. Nagy,
• Daniel Guillon,
• Jean-Louis Gallani and
• Bertrand Donnio

Beilstein J. Org. Chem. 2012, 8, 349–370, doi:10.3762/bjoc.8.39

• organic ligand coating and their resulting phase behaviour. Mechanisms proposed to explain the supramolecular organisation of the mesogens within the liquid-crystalline phases are discussed. Keywords: hybrid; liquid crystal; mesogen; mesomorphism; mesophase; nanoparticle; self-organisation; supramolecule

• various materials are classified according to the type of ligand coating used to impart mesogenic behaviour to the hybrid, highlighting their pivotal role in the design process. It is hoped that the reader will gain an understanding of the various factors that influence the mesophase behaviour of these

• -/needlelike and platelike shapes, different strategies may be possible for inducing mesophase behaviour in these hybrids. In the case of rod-/needlelike NPs with high aspect ratios, their inherent shape lends itself to the formation of LC phases such as nematics and smectics, subject to the reduction of

Synthesis of oleophilic electron-rich phenylhydrazines

• Aleksandra Jankowiak and
• Piotr Kaszyński

Beilstein J. Org. Chem. 2012, 8, 275–282, doi:10.3762/bjoc.8.29

• columnar rectangular phase (Cr 62 (Colr 60) I), a broad absorption band in the visible region, and redox potentials E0/+11/2 = +0.99 V and E0/−11/2 = −0.45 V versus SCE. Photovoltaic studies of 9 demonstrated hole mobility μh = 1.52 × 10−3 cm2 V−1s−1 in the mesophase with an activation energy Ea = 0.06

The interplay of configuration and conformation in helical perylenequinones: Insights from chirality induction in liquid crystals and calculations

• Elisa Frezza,
• Silvia Pieraccini,
• Stefania Mazzini,
• Alberta Ferrarini and
• Gian Piero Spada

Beilstein J. Org. Chem. 2012, 8, 155–163, doi:10.3762/bjoc.8.16

• material science [3][4]. In this context, one of the major research lines focuses on the investigation of the chirality transfer between “shape persistent” dopants and nematic solvents [2][5][6][7][8][9][10][11]. Thus, the chirality amplification from the molecular to mesophase level can be exploited for

Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens

• Sonja Findeisen-Tandel,
• Wolfgang Weissflog,
• Ute Baumeister,
• Gerhard Pelzl,
• H. N. Shreenivasa Murthy and
• Channabasaveshwar V. Yelamaggad

Beilstein J. Org. Chem. 2012, 8, 129–154, doi:10.3762/bjoc.8.15

• halogen atoms, F, Cl and Br, on the mesophase behaviour of three isomeric series was much lower than expected. On the other hand, an increase of the clearing temperature by 34 K was observed, caused by small lateral substituents. The electro-optical behaviour, especially the type of polar switching and

• ]. Tris(salicylideneanilines) having a discotic shape exhibit a room-temperature columnar mesophase [18][19]. Dendromesogens containing up to 64 peripheral mesogenic salicylideneimine fragments have also been reported [20]. Antiferroelectric behaviour has been claimed by Yablonski et al. to be exhibited

• of these salicylideneanilines with a photoactive azo compound. The observation of a B7 mesophase on the hexadecyloxy compound is surprising, because the central phenyl ring was not substituted by a nitro or cyano group as is the case for most of the other banana-shaped liquid crystals that form this

Improved syntheses of high hole mobility phthalocyanines: A case of steric assistance in the cyclo-oligomerisation of phthalonitriles

• Daniel J. Tate,
• Rémi Anémian,
• Richard J. Bushby,
• Suwat Nanan,
• Stuart L. Warriner and
• and Benjamin J. Whitaker

Beilstein J. Org. Chem. 2012, 8, 120–128, doi:10.3762/bjoc.8.14

• an average of five or more independent measurements. The mobilities were obtained from the slopes of these plots at each temperature. As shown in Figure 3c, the mobility is almost temperature-independent within the mesophase range. The hole mobility of 7c in the Colh phase at 185 °C was found to be

• most cases where a high time-of-flight mobility has been reported, the observation can be related to exceptionally high ordering in the mesophase, as revealed by X-ray diffraction (as in the Colp phases of hexakispropyloxytriphenylene and hexakisbutyloxytriphenylene, the H phase of

• hexakishexylthiotriphenylene and the Col phases of CPI discotics) [40][42]. In the case of these α-alkylated phthalocyanines, there is no evidence from the X-ray studies of any particular “higher” order in the mesophase but, in comparing them to the triphenylenes, it is important to take into account the larger size of the

Amphiphilic dendritic peptides: Synthesis and behavior as an organogelator and liquid crystal

• Baoxiang Gao,
• Hongxia Li,
• Defang Xia,
• Sufang Sun and
• Xinwu Ba

Beilstein J. Org. Chem. 2011, 7, 198–203, doi:10.3762/bjoc.7.26

• behavior, where a LC mesophase, on a second cooling, appeared at 40 °C and then disappeared at 145°C to form an isotropic melt (Figure 4). The high temperature for the isotropic melt of G3 is the result of hydrogen bond interactions of the amide groups which reinforce the columnar organization. The