Fafu Yang

Novel discotic liquid crystal oligomers: 1,3,5-triazine-based triphenylene dimer and trimer with wide mesophase

Series of novel 1,3,5-triazine-based triphenylene oligomers 7, 10 and 12 with large bridging polyaromatic core were designed and synthesised by simple procedures in high yields. Their structures were confirmed by FTIR, 1H NMR, ESI-MS and elemental analyses. Their mesomorphic behaviours were studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. 1,3,5-triazine-based triphenylene monomer 7 has no mesomorphic property, but 1,3,5-triazine-based triphenylene dimer 10 and 1,3,5-triazine-based triphenylene trimer 12 possess excellent mesomorphic properties. The mesomorphic temperature range of compound 12 was as wide as 180°C. These studies indicated that the mesomorphic properties were determined by the numbers of triphenylene units. More units of triphenylene in the oligomers resulted in better mesomorphic properties.

Mini-review: calixarene liquid crystals

Calixarene liquid crystals were important part among calixarene derivatives. The synthesis and mesomorphic properties of all kinds of calixarene liquid crystala have been discussed and reviewed. There are two methods to prepare calixarene liquid crystals. One way is to introduce the corresponding functional groups with long alkyl chains, which usually afford columnar liquid crystal with a rigid bowlic core. The organization of liquid crystals possesses interesting changes after the complexation of guests. Another way is to introduce triphenylene unit to obtain calixarenes bowlic column with triphenylene units as ancillary lateral columns or triphenylene column with calixarene units on ancillary side. Moreover, they showed interesting conversion between two kinds of liquid crystals before and after complexation with ions.

Novel triphenylene derivatives with acylthiosemicarbazide group: studies the influence of multiple H-bonding on mesomorphic properties

Series of triphenylene derivatives with multiple NH groups 3a, 3b, 4a, 4b, 5a and 5b were designed and synthesised by simple procedures in high yields. Their structures were confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), mass spectrometry (MS) and elemental analysis. Their mesophase behaviours were studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. The triphenylene derivatives 3a and 3b with two NH groups and triphenylene derivatives 4a and 4b with three NH groups possess excellent mesomorphic properties. Compounds 4a and 4b exhibited wider mesophase than compounds 3a and 3b. Triphenylene derivatives 5a and 5b with five NH groups have no mesomorphic properties. These results suggested the units of hydrogen bonds played the crucial roles on mesomorphic properties and acylthiosemicarbazide group with three NH groups was a good functional group for producing excellent mesomorphic properties.

Highly Efficient Liquid Membrane Transport of Dyes Using Calix[4]arene-Linked Triphenylene Dimers as Carriers

The extraction of dyes from aqueous phase to organic phase using calix[4]arene-linked triphenylene dimers (1a and 1b) with large π-cavity as extractants were examined. 1a and 1b showed outstanding extraction percentage for four common dyes [Orange G sodium salt (OG), Brilliant ponceau (BP), Methyl Green (MG), and Xylenol Orange disodium salt (XO)]. The highest extraction percentage of 1a was 95% for MG. Moreover, the abilities of liquid membrane transport of 1a and 1b for dyes were studied. The influences of pH value, concentration, solvent, stirring speed, and the temperature on liquid membrane transport was investigated to optimize the transport condition. The results of liquid membrane transport suggested 1a and 1b were excellent carriers for tested dyes with high fluxes. The high concentration in the source phase or membrane phase, CH2Cl2, high stirring speed, and low temperature were favorable for the efficiency of liquid membrane transport. The high extraction percentages and outstanding liquid membrane transport abilities indicated that 1a and 1b possessed excellent complexation for dyes based on the π-π stacking action between dyes and triphenylene units.

Novel supramolecular liquid crystals: cyclodextrin-triphenylene column liquid crystals based on click chemistry

Three new cyclodextrin-triphenylene derivatives 6, 7a and 7b were designed and synthesized by introducing a triphenylene unit into cyclodextrin based on click chemistry and further acylation of hydroxyl groups of the cyclodextrin unit. The column liquid crystal behaviour of cyclodextrin-triphenylene 7a was observed for the first time.

Excellent Ag+ selective receptors: Syntheses and complexation properties of novel biscalix[4]arene with benzalazine groups

By reacting mono-substituted or 1,3-bi-substituted [2-(p-formylphenyloxy)ethyloxy]-p-tert-butylcalix[4]arene (3 or 4) with hydrazine hydrate in ‘1+2’ or ‘2+2’ condensation mode, novel benzalazine-bridging biscalix[4]arenes 5 and 7 were conveniently obtained in the yields of 76 and 81%, respectively. Condensation of compound 4 and salicylide hydrazone gave a novel calix[4]arene benzalazine derivative 6 in the yield of 85%. The structures and conformations of all new compounds were characterised by elemental analyses, ESI-MS, 1H NMR and 1H–1H COSY techniques. Biscalix[4]arene 7 adopts a symmetrical cone conformation with tube cavity. The liquid–liquid extraction experiment showed that all new hosts possessed excellent complexation abilities towards soft metal cations. Compound 7 exhibited high complexation selectivity towards Ag+. The Ag+/Na+ and Ag+/Hg2+ extraction percentages of host 7 were as high as 73.1 and 54.9, respectively. The UV–vis spectra complexation experiments revealed that the complexation constant of receptor 7 with Ag+ was 1.9 × 105 M− 1 and the 1:1 stoichiometry of receptor 7–Ag+ complex was formed. The 1H NMR spectra complexation experiments suggested that Ag+ was bound in a cavity composed of two benzalazine groups on bridging chains.

Novel room-temperature perylene liquid crystals: synthesis of 1,7-dibrominated cholesterol–perylene bisimides with different ester-bridging chains and their mesomorphic properties

ABSTRACT Three novel 1,7-dibrominated cholesterol–perylene liquid crystals 6a, 6b and 6c with different ester-bridging chains were designed and synthesised in yields of 30–40%. Their structures were characterised by FT-IR, 1H NMR and HR-MS spectra. Their mesomorphic behaviours were studied by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction (XRD). Compounds 6a, 6b and 6c exhibit hexagonal columnar liquid crystalline phase at room temperature. Their mesomorphic temperature ranges are as wide as 140–162°C. Their fluorescence spectra suggested that they possess good fluorescence properties in solution. The soft ester-bridging chains are more favourable for room-temperature mesophase and high fluorescence than the rigid ester-bridging chain. GRAPHICAL ABSTRACT

Calixarene ionic liquids: excellent phase transfer catalysts for nucleophilic substitution reaction in water

The first examples of calixarene ionic liquids 3 and 6 with 3D-shaped cavities were obtained in high yields by reacting calix[4]arene or thiacalix[4]arene with 1,6-dibromohexane and then refluxing in 1-methylimidazole. The experiments of phase transfer catalysis in water suggested that they possessed excellent catalytic properties of aromatic nucleophilic substitution reaction and benzyl nucleophilic substitution. The optimized yields of product in catalytic reaction were as high as approximate 97% under mild reaction conditions. The cavities of calixarene skeleton played the crucial roles in catalysis and the stable cone conformation was favorable for catalysis.

Synthesis, mesomorphic and photophysical properties of novel triads and pentads of perylene liquid crystals with cholesterol units at the bay-position

Series of triads and pentads of perylene derivatives with two cholesterol units at the bay-position or four cholesterol units on both bay-position and imide position were designed and synthesized in yields of 55–65%. The influence of the different number and position of cholesterol substituents on mesomorphic properties and photophysical properties was studied. The results suggested that, in comparison with similar perylene derivatives with alkyl units at the imide position, the perylene liquid crystals with alkyl units at the bay-positions not only maintained excellent mesomorphic properties but also enhanced the fluorescence greatly. More cholesterol units resulted in a lower mesophase temperature, wider phase transfer temperature range, and higher fluorescence. A long spacer between perylene and cholesterol units led to more excellent mesomorphic properties and higher fluorescence.

Novel 1,2-3,4-Bridged and 1,3-Bridged Calix[4]arene Based on Large s-triazine Conjugate Systems: Synthesis and Complexation for Dyes

Two novel 1,2-3,4-bridged and 1,3-bridged calix[4]arenes 6 and 9 based on large s-triazine conjugate systems were designed and synthesized in high yields. The liquid-liquid extraction experiment showed that they possessed excellent extraction abilities towards one cationic and three anionic dyes [Orange I (OI), Methylene blue (MB), Neutral red (NR), Brilliant green (BG)]. The highest extraction percentage of compound 9 was 91.2% for BG. The complexation UV-Vis spectra of compounds 6 and 9 with four dyes indicated the existence of complexation action between hosts and guests with 1:1 ratio of complexation in DMSO solution. The association constants suggested that the 1,2-3,4-bridging structure was more favorable for producing excellent complexation abilities than 1,3-bridging structure. The association constant of compound 9 with BG was as high as 4.5 × 106 M−1.