Effect of molecular structure on mesomorphism XXI. Monodisperse tetrameric model compounds for liquid crystalline polymers

The dependency of twist-bend nematic liquid crystals on molecular structure: a progression from dimers to trimers, oligomers and polymers

“…Whereas there are numerous examples of liquid-crystalline trimers, relatively few tetramers have been reported. [126][127][128][129] Linear higher oligomers pose synthetic challenges, chiefly as efficient chromatographic purification is challenging, however some examples of pentamers exist. 130,131 In the context of the twist-bend nematic phase relatively few oligomeric materials are known to exhibit this state of matter.…”

“…Transition temperatures (1C) of the imine linked naphthyl-based dimers(126)(127)(128)(129) 114. Monotropic phase transitions are presented in parenthesis…”

Chiral liquid crystal tetramers

“…These higher oligomers have yet to receive the same level of attention as dimers but the most studied to date are liquid crystal trimers which consist of molecules containing three liquid crystal groups interconnected by two flexible spacers (see, for example, [22][23][24]. By comparison, the transitional behaviour of very few liquid crystal tetramers containing four mesogenic units and three flexible spacers has been reported in the literature [25][26][27][28][29][30][31][32][33][34][35] and of these only a small number exhibit smectic behaviour. 27,28,34,35 It is interesting to note that tetramers have been reported containing four differing mesogenic groups, one of which is cholesterylbased, and these exhibit columnar phase behaviour.…”

Odd–Even Effect in Liquid Crystal Tetramers

“…Furthermore, the transition properties of many liquid crystal dimers and trimers, which contain two or three mesogenic units, have been studied by many groups of workers [2][3][4][5]. In addition, some kinds of liquid crystal tetramers, which are defined as molecules containing four mesogenic units joined by three flexible spacers, have been prepared [6][7][8][9][10][11][12]. These compounds exhibit a remarkable odd-even effect in their transition properties, depending on the length and parity of the flexible spacers [1][2][3][4][5][6][7][8][9][10][11][12].…”