Synthesis and Characterization of Mesogenic Disklike Benzenetricarboxylates Containing Diacetylenic Groups and Their Polymerization

Abstract

Polymerizable disklike compounds that have a benzene ring core and three rigid diacetylenic units were prepared. The diacetylenic units were attached to the benzene ring via ester linkages. By varying number of alkoxy tail carbons and benzene rings of the disk, the morphological change of the compounds and their polymerization were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy, infrared spectroscopy (IR), and powder X-ray diffraction (XRD). Compound 7 with no alkoxy tail was glassy or small crystals at room temperature and showed crystal-to-crystal phase transition when heated. Compounds 8 with butyloxy tails, 9 with hexyloxy tails, and 10 with octyloxy tails showed monotropic transitions. When the compounds were cooled from the isotropic liquid states, birefringent phases with mosaic textures were observed. XRD study showed that compounds 9 and 10 had hexagonal columnar structures in their liquid crystalline (LC) states. The diacetylene compounds were polymerized by irradiation with UV in solid states or LC states. IR and UV−vis studies showed that the polymerization proceeded by 1,4-addition.

Synthesis and Chemical Properties of Diacetylenes with Pyridinium and 4,4′‐Bipyridinium Groups

“…In contrast, 4 has an asymmetrical structure, and it exhibits two absorptions at 2160 and 2200 cm À1 from the symmetric and asymmetric stretching vibrations of the C C bonds, respectively. This observation is consistent with the fact that the IR spectra of asymmetrical diacetylenes exhibit two absorptions for ñ(C C), as reported previously [14].…”

Star Mesogens (Hekates)—Tailor‐Made Molecules for Programming Supramolecular Functionality

“…[22,23] Molecules of the first group are also called mesogen trimers. This term is, however, not sufficiently precise, since linear, branched and bent trimers exist.…”

Imaging on a vapor deposited film by photopolymerization of a rod-like molecule consisting of two diacetylenic groups

“…4-Trimethylsilylethynylphenol and 4-ethynylphenol were prepared according to our previous report. 17 Bromine (39.9 g, 0.25 mol) was added to a vigorously stirred solution of potassium hydroxide (37.5 g) in water (100 mL) with cooling at 0 o C. 18 1-Hexyne (0.15 mol) in dioxane (80 mL) was added dropwise to the above mixture over 2 h. The reaction mixture was stirred for 40 h without further cooling. Then the mixture was extracted with chloroform.…”

“…12 It was reported that in a liquid crystalline state, the 1,4-polymerization also occurred to give highly ordered polymers. [13][14][15][16][17] In this work, we prepared a linear rod-like molecule, consisting of two diacetylenic groups, and examined its UV polymerization in the solid state. Thin films of the monomer were prepared by a physical vapor deposition or solution casting method.…”