Synthesis and mesomorphic properties of calix[4]resorcinarene–triphenylene oligomers

<p>By controlling the mol ratios of reactants, novel calix[4]resorcinarene–triphenylene monomer, dimer and tetramer were designed and synthesised in yields of 50–60% via Click chemistry. Their structures were characterised by NMR and MS. Their liquid crystalline behaviours were studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction analysis. The more triphenylene units on calix[4]resorcinarene resulted in the wider temperature scopes of mesophase and higher phase transition temperatures. The monomer <b>6</b> and dimer <b>7</b> showed the mixed columnar mesophase with hexagonal columnar structure and disordered lamellar columnar structure, and compound <b>8</b> possessed only disordered lamellar columnar mesophase. These research results suggest that calix[4]resorcinarene was a good platform to construct columnar liquid crystal and the mesomorphic properties were greatly influenced by the substituted numbers of mesogen units on calix skeleton.</p

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

<p>Three novel 1,7-dibrominated cholesterol–perylene liquid crystals <b>6a, 6b</b> and <b>6c</b> 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 <b>6a, 6b</b> and <b>6c</b> 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.</p

Syntheses of Novel Triphenylene-Aminoanthraquinone Dimers and Studies on Their Mesomorphic and Fluorescence Properties

<div><p></p><p>Two novel triphenylene-aminoanthraquinone dimers <b>4a</b> and <b>4b</b> were synthesized by reacting triphenylene carboxyl derivatives <b>3a</b> or <b>3b</b> with 2-aminoanthracene-9,10-dione in yields of 80% and 78%, respectively. Their structures were confirmed by ¹H NMR, electrospray ionization (ESI-MS), and elemental analysis. Their mesomorphic properties were studied by diffraction scanning calorimetry (DSC), polarizing optical microscopy (POM), and x-ray diffraction (XRD). The mesomorphic results suggested that they possess excellent mesophase properties. The investigation of fluorescence properties indicated that the strong cooperating fluorescence actions exist between two structural units. The fluorescence of dimers <b>4a</b> and<b>4b</b> are seriously quenched due to the electron transfer from donor (triphenylene unit) to acceptor (aminoanthraquinone unit).</p></div

The mesomorphic and photophysical properties of perylene liquid crystals with different bay-rigid spacers

<p>Three novel perylene derivatives were prepared by introducing two phenyl (biphenyl or naphthyl)-bridging cholesterol units on bay positions and six alkyl chains on imides positions. The influences of different bay-bridging spacers on mesomorphic properties and photophysical properties were investigated. They presented the ordered hexagonal columnar liquid crystalline behaviours, although the large aromatic spacers were bridged on the bay positions. The mesomorphic and photophysical properties could be tuned effectively by the structures of spacers on bay positions. The larger and more rigid aromatic spacer on bay positions resulted in higher phase transition temperatures and stronger fluorescence emission.</p