Design and Synthesis of Nematic Phases Formed by Disk‐Like Molecules

Synthesis and Mesophase Properties of Triphenylene Dimers Linked through Linear and Bent Alkyne‐Aryl‐Alkyne Bridges

“…Several design strategies have successfully produced the nematic phase by introducing packing constraints on the molecular self‐assembly [13] such that face‐to‐face (columnar) organisation is disfavoured. Examples include the hexa(aryl) esters ( 3 ) where steric interactions between the (twisted) substituents destabilise the columnar system [14–17] . Alkyne linkages are perhaps the most encountered structural feature in nematic discotics, providing (linear) structural rigidity with essentially barrier‐free rotation (in the absence of additional constraints).…”

“…Examples include the hexa(aryl) esters (3) where steric interactions between the (twisted) substituents destabilise the columnar system. [14][15][16][17] Alkyne linkages are perhaps the most encountered structural feature in nematic discotics, providing (linear) structural rigidity with essentially barrier-free rotation (in the absence of additional constraints). Multiple aryl-alkynyl substituents have been introduced onto benzene, triphenylene and other aromatic cores, leading to nematic behaviour.…”

“…Alkyne linkages are perhaps the most encountered structural feature in nematic discotics, providing (linear) structural rigidity with essentially barrier‐free rotation (in the absence of additional constraints). Multiple aryl‐alkynyl substituents have been introduced onto benzene, triphenylene and other aromatic cores, leading to nematic behaviour [16,17] . Alkyne and particularly diyne linkages have been used to join discotic cores to give nematic materials (e. g., 5 ), [17–19] in contrast to systems linked by flexible spacers of appropriate length that retain the stable columnar phase (e. g., 4 ) [20–23] .…”

“…Multiple aryl-alkynyl substituents have been introduced onto benzene, triphenylene and other aromatic cores, leading to nematic behaviour. [16,17] Alkyne and particularly diyne linkages have been used to join discotic cores to give nematic materials (e. g., 5), [17][18][19] in contrast to systems linked by flexible spacers of appropriate length that retain the stable columnar phase (e. g., 4). [20][21][22][23] We have found that rigid twins (e. g. 6, 7, where there are two rigid links resulting in a macrocycle) also tend to only give stable nematic phases (Figure 2).…”

A modified route to unsymmetrically substituted triphenylenes, new functionalised derivatives and twins, and the smallest reported triphenylene mesogen

“…Our group has made a number of contributions to this area, most recently concentrating on unsymmetrical, differentially substituted [7][8][9][10][11] and twinned systems. [12][13][14][15] Recent goals have been to explore structural parameters linked to discotic nematic mesophase formation [16] and to exploit the strong tendency of triphenylenebased systems to form mesophases to incorporate additional organic functionality into discotic phases. [17] Selected highlights include the intriguing nematic dehydroannulene twins 1, [12] pyrazine linked twin 2 [18] and mesogenic triphenylene-perylene-triphenylene triads 3.…”