TNF Induced Switching of Columnar Rectangular to Hexagonal Assemblies in a New Class of Triphenylene-Based Room Temperature Discotic Liquid Crystals

Abstract

A straightforward synthesis of triphenylene-based oligomeric systems that self-organize into room temperature columnar structures is presented. The compounds with longer spacer length (m = 10 and 12) exhibit columnar rectangular (Col) mesophase whereas the compound with m = 8 exists in glassy Col state. Interestingly, the Col self-assembly of these compounds switches to columnar hexagonal (Col) on doping the compounds with 2,4,7-trinitrofluorenone (TNF). For the dopant concentration of 1:1 with respect to native compound, an intermediate transition state between Col and Col phase was observed which completely transformed into the hexagonal phase on increasing the concentration to 1:2 (compound: TNF) and afterward. Both the Col and Col self-assemblies have been well resolved by detailed X-ray analysis. These kind of oligomeric compounds generally possess a combination of desirable alignment properties analogous to monomeric compounds and long-lived glassy states similar to that of polymeric mesogens. In addition, charge hopping behavior is expected to increase in these compounds due to donor-acceptor interactions. Overall, these compounds can find possible potential applications in semiconductor devices.

Nanoporous Films with Photoswitchable Absorption Kinetics Based on Polymerizable Columnar Discotic Liquid Crystals

“…When the TB template was removed, the spacing increased to 4.52 nm (Figure D, the gray line). A reflection from the interdisk distance at wide angles is absent in the diffractogram, indicating disordered stacking in the polymerized material …”

“…A reflection from the interdisk distance at wide angles is absent in the diffractogram, indicating disordered stacking in the polymerized material. 34 Photoisomerization of TB•Azoac 3 in Solution and in Films. Trans-to-cis photoisomerization of Azoac in solution was monitored with UV−vis spectroscopy and the slower cisto-trans thermal relaxation was monitored with both UV−vis and 1 H NMR spectroscopy.…”

Supramolecular organogels based on mesogenic 2,7-difunctionalized triphenylenes as a simple system for water content assessment in light alcohols

“…4 Moreover, several kindred compounds, in which the core is not rigorously triphenylene, but nitrogenated analogs, like hexaazatriphenylenes 5 also exhibit Col mesophases. Intercalation of acceptor moieties like trinitrofluorenone (TNF) between TP cores promotes the occurrence of columnar nematic (N c ) or Col h mesophases in otherwise non-mesogenic TP-based polymers 6 as well as switching between Col r and Col h mesophases in TP-based oligomers 7 . When the hexasubstituted TP bears one or more terminal functional groups, the range of self-organizing possibilities increases remarkably.…”

Room-Temperature Columnar Liquid Crystals from Twisted and Macrocyclic 9,9′-Bifluorenylidene Mesogen with Ambipolar Carrier Transport Properties

“…These films play an essential role in improving carrier-transport properties, thereby optimizing device performance. , Among columnar LC materials explored so far, most of them are accompanied by high phase-transition temperatures and narrow temperature ranges to observe the mesophase since columnar LC materials generally consist of a large planar π-conjugated mesogen, where the expanded π-core is efficiently stacked via strong intermolecular interactions. − Thus, columnar LC materials at room-temperature and over a wide temperature range are highly desirable and of great importance for their widespread applications in organic electronic devices. Furthermore, the shape-persistent macrocyclic mesogens with extended π-conjugation have many potential applications, such as functioning as a nanospace for specific molecular recognition and furnishing the desirable properties into the LC mesophase. − Generally, it is challenging to organize large macrocyclic molecules exhibiting a homogeneously ordered columnar LC mesophase over a wide temperature range, which is restricted by molecular design and synthetic difficulties. − Moreover, such large π-conjugated molecules usually undergo a high phase-transition temperature to liquid crystal and to isotropic liquid and formation of LC mesophases in a narrow range of temperature.…”