Liquid Crystalline Polyacetylenes:  Synthesis and Properties of Poly{n-[((4‘-cyano-4-biphenylyl)oxy)carbonyl]-1-alkynes}

Abstract

It is generally believed that cyano functionality is "toxic" to the classical MoCl 5-and WCl6based metathesis catalysts, but we here present such an example in which a group of cyano-containing acetylene monomers are polymerized by the "simple" metal halides. The WCl6(-Ph4Sn) catalysts in dioxane initiate the polymerizations of n-{ [(4′-cyano-4-biphenylyl)oxy]carbonyl}-1-alkynes (AnCN; n ) 2, 3, 8), yielding polymers (PAnCNs) with relatively narrow molecular weight distributions (Mw/Mn down to 1.3). The same metal-halide mixtures in toluene, however, are generally ineffective in polymerizing AnCNs, suggesting that the tungsten-oxo complexes are involved in the active center formation. The differential scanning calorimetry, polarizing optical microscopy, and X-ray diffractometry analyses reveal that all the PAnCNs are mesomorphic, with the longer flexible spacer favoring the better ordering of the mesogenic groups. PA2CN shows monotropic nematicity, PA3CN exhibits enantiotropic nematicity, and PA8CN displays enantiotropic smecticity with an interdigitated molecular packing arrangement (s Ad) over a wide temperature range (ca. 110 °C). In-domain banded structures within the sAd layers of PA8CN are observed during the transit of the ba ˆtonnets to the focal-conic fan textures, and the formation of large scale band morphology is achieved by the application of shear force to PA8CN in its liquid crystalline state.

Synthesis, helicity, thermal stability, and low infrared emissivity of optically active polyacetylenes carrying tyrosine pendants

“…As a result, it can induce the polymer chain to spiral in a helical conformation. [19][20][21] Moreover, a variety of polyacetylenes containing mesogenic and chromophoric groups with ester, [22,23] ether, [24][25][26][27] amine, [28][29][30] thio, [31,32] and cyano [33,34] functionalities have been successfully synthesized and potentially used as liquid crystals, mesomorphic luminescent and conductive materials, and so on. Natural amino acids have been generally applied in the preparation of optically active materials as one of the most significant chiral resources.…”

“…[22][23][24][25][26][27][28][29][30][31][32][33][34] However, we had an interest in directly connecting chiral amino acid pendants to the polyacetylene backbone, and in this study, we made our best efforts to polymerize monosubstituted propiolamides (HC≡CCONHR), in which the triple bond was directly attaching to the carbonyloxy group. We used propiolic acid and tyrosine methyl esters in the synthesis of the monomer containing tyrosine derivatives as a functional group.…”

Crystalline Behavior and Structure of a Liquid Crystal Compound, 5-{[4′-(((Pentyl)oxy)-4-biphenylyl)carbonyl]oxy}-1-pentyne

“…They not only disturb the standard recipe for designing side-chain liquid crystalline polymers (flexible backbone＋spacer＋mesogenic moiety), but also have superior properties, such as photoconductivity, 1 light-emitting, [2][3][4][5] and mesomorphic properties [5][6][7][8][9] due to their conjugated main chain and biphenyl mesogen.…”

“…[10][11][12] However, detailed studies of their crystalline behavior and the relationship between crystalline behavior and chemical structure are still lacking. It is well known that the microstructure of substance usually has great effects on its macroscopical property.…”

Phase transition behavior and structure of the thermotropic liquid crystal 6-{[(4′-{[(undecyl)carbonyl]oxy}biphenyl-4yl)carbonyl]oxy}-1-hexyne

“…In recent years, side-chain liquid crystalline (LC) polyacetylenes have attracted great interest among scientists in academic and industrial field owing to their unique light-emitting properties [1][2][3], photoconductivity [4] and mesomorphic properties [5][6][7][8].…”