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

Abstract

We report the unexpected observation of columnar mesophase formation in a simple 2,7-dibromotetramethoxytriphenylene – by far the most lightly substituted discotic mesogen in this class. This derivative was prepared alongside the 3,6-dibromotriphenylene isomer to demonstrate an alternative, modified synthetic strategy that permits late-stage interchange of alkyl chain substituents. The new method is employed alongside the original route to deliver several new materials, including a conjugated ferrocene-triphenylene-ferrocene triad, a BODIPY-triphenylene-BODIPY triad and a new nematic twin linked through imine bridges

Strategies for promoting discotic nematic phases

“…Indeed, triphenylene-based discotic dimers linked by conformationally constrained bridging groups have been observed to form nematic phases. 24–27…”

“…Indeed, triphenylene-based discotic dimers linked by conformationally constrained bridging groups have been observed to form nematic phases. [24][25][26][27] Dimers dDBP (6,6), dDBP (10,10), dDBP (10,6), and dDBP(6,10) were prepared via Steglich esterification (Scheme 1), coupling previously reported carboxylic acids DBP-A(6) and DBP-A(10) 28 with the corresponding alcohols DBP-OH(6) and DBP-OH (10). DBP-OH (10) was synthesized in 85% yield using the conditions reported for DBP-OH(6), 29 from the condensation of the phenanthrene quinone (Q10) with 3,4-diaminophenol.…”

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

“…[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). [24][25][26] In this case we have reasoned that columnar arrangement of the triphenylene cores would prevent efficient packing due to the void region created in the centre of the macrocycle and is therefore disfavoured. [24,27]…”