Synthesis and specific features of mesomorphic behavior of new polysubstituted triphenylenes

Previously unknown 2,3,6,7,10,11-hexakis(dodecyloxy)triphenylene and -(tetradecyloxy)triphenylene were synthesized. The structures of the synthesized compounds were proved by elemental analysis and spectral methods. Polymesomorphism was found for the first time and studied for substances of the hexaalkoxytriphenylene homologic series, as well as liotropic mesomorphism in a series of organic solvents.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1676–1681, August, 2004.     

Synthesis and study of heptasubstituted triphenylenes with chiral fragments and predictable type of mesomorphism

The forecasting of columnar and chiral mesomorphism was done for the new series of triphenylene derivatives. The mesomorphic properties of the two heptasubstituted triphenylenes containing chiral fragments were studied. The prediction results agreed well with the experimental data. Anilides of 1-amino-2,3,6,7,10,11-hexa(heptyloxy)triphenylene with abietic and dihydrocholic acids were found to exhibit the enantiotropic columnar dimesomorphism and to display the chiral columnar mesophases in the low-temperature range. The anilides obtained possess a lower thermal stability and extended interval of the mesophase existence than the initial amine.     

Synthesis and investigation of triphenylene discotic derivatives with donor and acceptor groups and with predictable type of mesomorphism

Prognosis of columnar mesomorphism is performed, five new hexa-and hepta-substituted triphenylene derivatives with donor and acceptor groups are synthesized and their mesomorphoc properties are stusied. Good agreement is achieved between predictions and experiments. The synthesized triphenylene derivatives are found to display enantiotropic columnar mesomorphism. 1-Amino-2,3,6,7,10,11-hexaheptyl-xytriphenylene anilides of 2,3,5-triiodo-, 3,4,5-trihydroxy-and 4-nitro-benzoic acids reveal enantiotropic dimesomorphism. Also found decrease in thermal stability and extension of the interval of existence of mesophase at introduction to triphenylene frame of substituents with acceptor groups at the amino group.     

不对称苯并菲盘状液晶的合成及取代基对介晶性的影响

合成了一系列新型含间位二硝基苯甲酸酯不对称苯并菲盘状液晶化合物2-(3,5-二硝基苯甲酰氧基)-3,6,7,10,11-五烷氧基苯并菲(3a～3f). 通过偏光显微镜(POM)和差示扫描量热计(DSC)对其介晶性进行了研究. 结果显示: 此类化合物有高的清亮点, 稳定的六方柱状相以及较宽的介晶相范围, 且随着软链碳原子数的增加, 化合物的熔点和清亮点均出现下降趋势, 但六方柱状相的有序性却没有发生很明显的变化. 同时通过与其它三类苯并菲盘状液晶2-苯甲酰氧基-3,6,7,10,11-五烷氧基苯并菲(4a～4f), 2-二茂铁甲酰氧基-3,6,7,10,11-五烷氧基苯并菲(5a～5f), 2,3,6,7,10,11-六烷氧基苯并菲(6a～6f)的对比研究, 探讨了酯基, 强吸电子基团, 以及取代官能团体积对介晶性的影响. 证实了苯并菲化合物中分子结构小的变化将引起介晶性大的改变.     

Studies on relation between columnar order and electrical conductivity in HAT6 discotic liquid crystals using temperature-dependent Raman spectroscopy and DFT calculations

The vibrational property of 2,3,6,7,10,11-hexakis(hexyloxy)triphenylene (HAT6) discotic liquid crystal (DLC) material is investigated in this research by using temperature-dependent Raman spectroscopy technique. One-dimensional (1D) charge transport mechanism in the DLC molecules is enabled in the columnar liquid crystalline (D_h) phase. The result indicates a high core-to-core correlation in the liquid crystal columnar phase, which has a ‘memory’ like effect that extends into isotropic phase at femtosecond timescale. This correlation is also confirmed through electrical conductivity measurement of DLCs, in which the electrical conductivity is enhanced in the DLC phase. DFT simulation was also carried out in order to elucidate the basic properties of HAT6 such as the band gap in the light of Raman spectra. An interesting outcome is that a freely unspecified boundary model produces in a more flexible molecule, resulting in a reduced band gap. Thus, this work provides an understanding of relationship between columnar order and electrical conductivity of HAT6 molecule, and potential strategy for design of DLCs in electronics application.     

Alignment behavior for novel triphenylene compounds possessing fluoroalkylated side chains on modified substrates

The alignment behavior of the triphenylene compounds possessing fluoroalkylated side chains was investigated for the hexagonal columnar (Col_h) mesophase on the polyimide-, cetyltrimethylammonium bromide (CTAB)-, and indium-SnO₂ (ITO)-coated glass substrates by polarizing optical microscopy. It was found that 2,3,6,7,10,11-hexakis(1H,1H,2H,2H,3H,3H-perfluoroheptyloxy)- and 2,3,6,7,10,11-hexakis(1H,1H,2H,2H,3H,3H-perfluorononyloxy)-triphenylenes exhibit a spontaneous homeotropic alignment on these substrates, in contrast to the non-uniformity of alignment of Col_h phase in the corresponding hydrocarbon mesogens. On the other hand, it was also found that 4,4,4-trifluorobutyloxy, 4,4,5,5,5-pentafluoropentyloxy and 4,4,5,5,6,6,6-heptafluorohexyloxy derivatives do not show such a spontaneous homeotropic alignment on these substrates. These results indicate that the spontaneous homeotropic alignment of the Col_h phase could be easily attained by the introduction of an appropriate number and length of the fluoromethylene chains in the peripheral parts of discogens.     

Synthesis of unsymmetric triphenylene discotic liquid crystals with a semi-fluorinated chain and the influence of fluorophobic effect on mesogenic behavior

The fluorophobic effect of the semi-fluorinated chain of discotic molecules efficiently improves the stability of columnar mesophase.Low symmetric discogens exhibit decreased melting points and wide mesophase ranges.A series of triphenylene derivatives 1,C18H6(OCnH2n+1)4(OMe)(O2CC2H4C6F13),and their hydrocarbon analogues 2,C18H6(OCnH2n+1)4(OMe)(O2CC8H17),n = 4―8,were synthesized for the investigation of the influence of semi-fluorinated peripheral chain and molecular symmetry on mesomorphism.The structures ...     

Three-dimensional nets from star-shaped hexakis(arylthio)triphenylene molecules and silver(I) salts

This article reports a number of functional 3D networks based on the coordination bonds between the silver(I) ion and polycyclic aromatic 2,3,6,7,10,11-hexakis(organylthio)triphenylene (HRTT) molecules. First, 2,3,6,7,10,11-hexakis(phenylthio)triphenylene (HPhTT) chelates with AgBF4 (or AgTf, where Tf is triflate) in the presence of hexafluorobenzene to form a 3D network (composition, HPhTT x AgBF4; space group, I4), where each Ag(I) atom is bonded to three HPhTT molecules and acts as a three-connected node that interconnects the trigonal HPhTT ligands. In addition to the relatively rare 8(2) x 10-a topology, the network features distinct channel-like domains that incorporate various solvent molecules (e.g., acetone and tetrahydrofuran). The solvent molecules can be evacuated to produce a stable and crystalline apohost network, in which the solvent-accessible fraction of the cell volume is calculated to be about 16%. Second, chelation of 2,3,6,7,10,11-hexakis(4-methoxyphenylthio)triphenylene (HMOPhTT) and AgSbF6 in a 1:1 ratio results in a 3D network featuring a similar 8(2) x 10-a topology and Ag(I) coordination environment. However, the crystallographic symmetry (space group Cc) is lowered, and the feature of porosity is much less distinct. The 3D networks show strong room-temperature fluorescence bands with lambda(F,max) = 450 nm, due to the pi-electron fragment of the triphenylene group.     

Novel triphenylenoimidazole discotic liquid crystals

A novel discotic core was constructed by fusing imidazole unit with well-known triphenylene discotic core. Two new imidazole fused unsymmetrically substituted triphenylene derivatives were prepared and characterized. While the molecular structures of the new compounds were verified by ¹H NMR, UV, MS and elemental analysis, their liquid crystalline properties were determined by polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction studies. These triphenylenoimidazole derivatives were found to exhibit hexagonal columnar mesomorphism over a wide temperature range.     

Liquid crystals II. The tail design via β-oxygen atom modification for the remarkably enhanced stability of hexakis (alkanoyloxy) triphenylene mesophase

A new family of liquid crystalline compounds, 2,3,6,7,10,11-hexakis(3-oxaalkanoyloxy)triphenylene, was found to exhibit very wide mesomorphic temperature ranges, providing a promising design principle for mesogen construction, β-oxa modification of tail alkyls.     

Polysubstituted triphenylenes with active groups. Molecular parameters, synthesis, structure, and mesomorphism

Molecular parameters of hexaalkoxytriphenylenes with different substituents on the periphery of the triphenylene nucleus of known and hypothetical structures are calculated. The probability of a discophase for compounds of this series is estimated from molecular parameters. Several compounds of this series having polar groups (NO₂, NH₂) in the 1 position of the triphenylene nucleus have been synthesized. The compounds synthesized were investigated by thermopolarizing microscopy and X-ray diffraction analysis. The data on the mesomorphism of the new compounds are in good agreement with our prediction that alkoxytriphenylenes with polar groups have a discophase. It is established that introduction of an electron-accepting group at position 1 of the triphenylene nucleus expands the temperature range of existence of the discophase to room temperature. On the contrary, introduction of an electron-donating group narrows this interval. Compounds of this series presumably have a hexagonal columnar structure. Ivanovo State University. Warsaw University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 464–472, May–June, 1998. This work was supported by RFFR grant No. 96-02-19036.     

含氟链不对称苯并菲盘状液晶的合成及疏氟效应对介晶性的影响

盘状液晶分子中引入氟代烃链并利用疏氟效应（fluorophobic effect）能有效稳定分子的柱状堆积;低对称性的盘状分子有较低的熔点和宽的介晶相温度范围．基于此,本文设计并合成了一系列半氟酯链的不对称苯并菲化合物C18H6（OCnH2n＋1）4（OCH3）（O2CC2H4C6F13）（1）,及相对应的不含氟化合物C18H6（OCnH2n＋1）4（OCH3）（O2CC8H17）（2）,n=4—8．化合物结构通过核磁和质谱表征．介晶性通过差示扫描量热法和偏光显微镜进行了研究．结果显示：化合物均为柱状互变热致液晶．含氟链化合物1a—1e与相对应的化合物2a-2e比较,有更高的熔点和清亮点．合成的多数化合物为室温液晶．     

Construction, synthesis and study of new discotic mesogens

The calculation and analysis of molecular parameters (MPs) has been carried out for five series of triphenylene derivatives and crown ether derivatives (30 molecules) containing chiral or complexing centers. The values of the MP were used to predict possible occurrence of columnar and nematic mesomorphism in these series. Several representatives of these series were synthesized and their mesomorphic behavior was studied. A special attention was paid to enamine ketone derivatives of crown ether, in which the transition from the liquid-crystal state to the vitreous state with retention of the mesophase structure at the ambient temperature was observed.     

Helical arrangement of a hydrogen‐bonded columnar liquid crystal induced by a centered triphenylene derivative bearing chiral side‐chains

A hydrogen‐bonded helical columnar liquid crystal was synthesized, in which the helical structure is induced by a centered triphenylene derivative bearing chiral side‐chains. The triphenylene derivative, 2,6,10‐tris(carboxymethoxy)‐3,7,11‐tris((S)‐(‐)‐2‐methyl‐1‐butanoxy)triphenylene ( TPC4(S) ), and a dendric amphiphile, 3,5‐bis‐(3,4‐bis‐dodecyloxy‐benzyloxy)‐N‐pyridine‐4‐yl‐benzamide ( DenC12 ), were mixed in a 1:3 ratio to obtain a complex, TPC4(S)‐DenC12 . Analyses by ¹H‐NMR spectroscopy, diffusion ordered spectroscopy (DOSY), CD spectroscopy, infrared (IR) spectroscopy, polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X‐ray diffractometry revealed that TPC4(S)‐DenC12 self‐assembles to form helical columnar stacks in solution and a helical columnar liquid crystal in bulk. The hydrogen bonding between TPC4(S) and DenC12 is essential for the helical columnar organization, and the preference for a one‐handed helical conformation is likely derived from the steric interaction between the chiral side‐chains and the dendric amphiphiles in the packing of the hydrogen‐bonded columnar assemblies. Copyright © 2008 John Wiley & Sons, Ltd.     

Improvement of the fluorescence quantum yield of triphenylene by the rotational effect of 4-(trimethylsilyl)phenyl groups

The fluorescence quantum yield of triphenylene is low because the transition moment between the HOMOs and the LUMOs is negligibly small. To improve the fluorescence quantum yield, break of the symmetrical structure of triphenylene is necessary. We found that the rotational effect of the 4-(trimethylsilyl)phenyl groups of 2,3,6,7,10,11-hexakis[4-(trimethylsilyl)phenyl]triphenylene is effective to break the symmetry in spite of the symmetrical structure, leading to improvement of the fluorescence quantum yield.     

半氟烃链苯并菲盘状液晶的合成及其介晶性

全氟烃链的憎氟效应(fluorophobic effect)可有效地促使棒状分子形成近晶相, 并稳定液晶相. 为进一步探讨氟效应对盘状分子介晶性的影响, 合成了一系列全氟酯链的苯并菲化合物C₁₈H₆(OC_nH_2n＋1)₅(OCOC₂H₄C₆F₁₃) (a), 以及另一系列相对应的不含氟化合物C₁₈H₆(OC_nH_2n＋1)₅(OCOC₈H₁₇) (b), n＝4～9. DSC检测和偏光显微镜观察显示两类化合物都为柱状相热致型液晶. 化合物a与相对应的化合物b比较, 其熔点和清亮点上升, 柱状相的热稳定性增强.     

The (salophen)-bridged Fe/Cr (III) capped complexes with triphenylene core: Synthesis and characterization

This article describes synthesis of the difference carboxylic acid derivatives of triphenylene and its complexation properties with Fe/Cr (III)-salophen. For this purpose, the carboxylic acid derivatives of 2,3,6,7,10,11-hexahydroxytriphenylene were synthesized and then reacted with four new Fe(III) and Cr(III) complexes involving tetradenta Schiff bases bis(salicylidene)-o-phenylenediamine-(salophenH₂). The prepared compounds were characterized by means of elemental analysis carrying out infrared spectroscopy (IR), thermogravimetric analysis (TG), nuclear magnetic resonance (¹H NMR), elemental analysis and magnetic susceptibility measurement. The complexes can also be characterized as low-spin distorted octahedral Fe(III) and Cr (III) bridged by carboxylic acids.     

苯丙炔酸和苯丙烯酸酯苯并菲盘状液晶的合成及介晶性

合成了7个含苯丙炔酸和苯丙烯酸酯链的苯并菲盘状液晶化合物C₁₈H₆(OC_nH_2n＋1)₅O₂CR' [R'＝C≡CC₆H₅, n＝4～9 (1a～1f); R'＝CH＝CHC₆H₅, n＝6 (1g)]. 该系列化合物结构通过¹H NMR, IR和元素分析表征. 液晶性通过差示扫描量热法和偏光显微镜进行了研究, 结果显示: 化合物均为六方柱状相热致型液晶; 含苯丙炔酸酯链苯并菲盘状液晶化合物1a～1f, 随着烷氧链的增长, 清亮点呈现逐渐下降的趋势; 对于含苯丙烯酸酯链苯并菲化合物1g与具有同样软链长度的炔基酯链苯并菲化合物1c比较, 具有更低的熔点和结晶点, 而它们的清亮点几乎一致, 因而化合物1g有更宽的介晶性温度范围.     

Mesomorphic phase transition behaviour of photopolymerisable liquid crystalline triphenylene ether compounds

This report discusses the preparation and the unusual mesomorphism of three homologues of photopolymerisable triphenylene ether compounds. These homologues showed ‘a cold crystallisation’ on heating differential scanning calorimetry curves, and this phenomenon is attenuated with increase methylene units, spacers between the triphenylene core and the terminal photopolymerisable acrylate group. Classical textures of hexagonal columnar (Col_h) mesophase were observed by polarising optical microscopy for all three photopolymerisable mesophase compounds described here. Also described is the mesomorphism of their intermediates, hydroxylalkoxytriphenylenes. In some cases, the discotic columnar hexagonal mesophases were confirmed by wide angle X-ray scattering techniques.     

Synthesis of Mixed Tail Triphenylene Discotic Liquid Crystals： Molecular Symmetry and Oxygen-Atom Effect on the Stabilization of Columnar Mesophases

Small change in chemical structure of discotic liquid crystals can cause big difference in their mesomorphism. Replacing of the alkoxy peripheral chains of triphenylene by oxygen-atom containing ester chains would result in novel mesomorphism. A series of mixed tail triphenylenes containing propoxyacetyloxy and alkoxy, abbreviated as C18H6（OCnH2n＋1）3（OCOCH2OC3H7）3, n=4-8, and hexa（propyloxyacetyloxy）triphenylene, C18H6（OCOCH2OC3H7）6 were synthesized. Thermal gravimetry analysis （TGA） of three discogens showed that they had good thermal stability till 350 ℃. The mesomorphism was investigated through differential scanning calorimetry （DSC） and polarized optical microscopy （POM）. The preliminary X-ray diffraction （XRD） results of one compound showed that it exhibited ordered hexagonal columnar （Colho） mesophase. These mixed tail triphenylene derivatives possessed much stable Colho mesophase and wider mesophase ranges than their hexaalkoxytriphenylene C18H6（OR）6 and hexaalkanoyloxytriphenylene C18H6（OCOR＇）6 analogues. The asymmetrical compounds 2,6,11-trialkoxy-3,7,10-tri（2-propyloxyacetyloxy）triphenylenes with n=5-8 displayed higher clearing points and wider temperature ranges than their symmetrical isomers 2,6,10-trialkoxy-3,7,11-tri（2-propyloxyacetyloxy）- triphenylenes, while C18H6（OCOCH2OC3H7）6 had the highest clearing point due to the β-oxygen-atom effect.