Electroluminescent segmented liquid crystalline trimers

Synthesis and thermal properties of liquid crystal trimers comprising cyanobiphenyl and salicylaldimine anisometric segments

“…7,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Specifically, the transition temperatures display a remarkable odd-even effect as the length and parity of the spacer are varied. Such a feature is also seen in the present T-n series of trimers, as expected.…”

“…Kelly et al, have recently reported the photoluminescent and electroluminescent LC trimers formed by covalently linking an aromatic light emitting central core with two cholestanyl entities through two flexible spacers. 27 The trimers consisting of electron deficient (cyanobiphenyl) unit(s), and electron rich (Schiff's base/azobenzene) core(s) exhibit nematic and/or smectic behavior. 14,[24][25][26] In particular, trimers (TAZOn series) formed by tethering two cyanobiphenyls with a central electron rich azobenzene core through two flexible spacers of varying length and parity display smectic behavior solely.…”

“…7 Thus far, three obvious kinds of trimers viz., symmetric 13,18,23 dwhere all the constituent mesogenic (A-A-A) units are identical, mixed 11,12,[14][15][16][17]21,22,[24][25][26][27] dtwo of the mesogens (A-B-A) are identical, and nonsymmetric 19,20 dnone of the mesogenic (A-B-C) units are identical, have been prepared and characterized. Seemingly, the mixed trimers, including supramolecular 28,29 systems (where the mesogenic segments are formed/ linked through the hydrogen-bond interactions) and metal-containing ones, 21 are reported in large numbers.…”

“…Liquid crystalline linear trimers (also referred to as trimesogens or triplet LCs), 7,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] wherein three rod-like mesogenic entities are tide terminally through two flexible spacers, are considered as an important class of oligomers not only because of their interesting thermal behavior but also they help in studying how the LC behavior evolves from dimers to polymers. 7 Thus far, three obvious kinds of trimers viz., symmetric 13,18,23 dwhere all the constituent mesogenic (A-A-A) units are identical, mixed 11,12,[14][15][16][17]21,22,[24][25][26][27] dtwo of the mesogens (A-B-A) are identical, and nonsymmetric 19,20 dnone of the mesogenic (A-B-C) units are identical, have been prepared and characterized.…”

Synthesis and mesomorphic properties of chiral nematic liquid crystals based on cholesterol

“…[1][2][3] Many liquid crystalline compounds consisting of a cholesteryl ester unit as a chiral segment joined to different mesogenic moieties such as benzoate ester, Schiff's base, azobenzene, biphenyl, tolane, etc., through flexible spacers, have been synthesised and extensively studied. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Their liquid crystalline properties are affected by spacer length and polarity, the length of the terminal group attached to the aromatic rings, as well as the type of linking group between the spacer and mesogenic units, such as ethers and esters. They have shown interesting mesomorphic phase behaviour including SmA phases, TGB phases, blue phases and the N* mesophases.…”