W-shaped liquid crystalline dimers

Abstract

We present a study of liquid crystalline bent-core dimers with a novel W-shaped molecular structure exhibiting broad polymorphism.

Distinctive dielectric properties of nematic liquid crystal dimers

“…Calamitic, discotic or bent-core mesogenic groups have been used among others as 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 F o r P e e r R e v i e w O n l y building blocks for dimeric systems, connected by longitudinally or laterally by flexible linking groups of different types, length or parity, and revealing a highly interesting hierarchy of mesomorphic behaviour [6][7][8][9][10][11][12][13]. However, in the recent years the simplest calamitic-calamitic dimers have attracted considerable attention due to the discovery of a novel nematic phase, originally for cyanobiphenyl based odd dimers with methylene links ( , -bis(4,4'-cyanobiphenyl)-alkanes CBnCB).…”

Competing synclinic and anticlinic interactions in smectic phases of bent-core mesogens

“…[2][3][4][5][6][7][8][9] These molecules are either dimers, composed of two mesogenic parts connected with a flexible spacer with an odd number of atoms, [10][11][12][13][14] or they have an extended rigid core with usually a central metasubstituted phenyl or naphthalene ring. [15][16][17][18][19][20][21][22][23] A rigid bent-core structure restricts molecular rotation, which in turn might induce correlations of dipoles. Bent dimers also facilitate low bend elasticity, 24,25 which leads to a heliconical molecular arrangement.…”

“…Bent dimers also facilitate low bend elasticity, 24,25 which leads to a heliconical molecular arrangement. 26 Consequently, rigid bent-core mesogens have a strong tendency to form polar phases, [14][15][16] and flexible dimers readily form helical phases. 27 In this study, our focus is on the molecules that combine both characteristics.…”

Bent-core dimers with top-to-bottom linkage between central units

“…5 With rising attention LC bent-core dimers and oligomers have also been investigated for their diversity of mesomorphic properties in comparison with monomeric LCs. In the molecular structure of dimers constituting mesogenic units are joined in various modes, the most frequently end-toend, [6][7][8][9][12][13][14][15][16]27 and scarcely side-to-end 11 and top-to-top. 10 The mesomorphic properties of the end-to-end joined dimers are sensitive to the character of the spacer: materials with an alkylene spacer exhibited nematic and smectic phases [9][10][11][12] and columnar phases 13,14 depending on the length of the spacer, respectively.…”