Liquid Crystalline Magneto-Optically Active Peralkylated Azacoronene

Abstract

Organic Faraday rotators have gained significant attention in recent years as a promising alternative to traditional inorganic magneto-optical (MO) materials as a result of their lower cost, superior mechanical properties, and potential for large-scale deployment. This interest is peaked by the fact that a number of high symmetry, rigid, strongly optically absorbing organic chromophores display Verdet constants an order of magnitude higher than commercial inorganic Faraday rotators. Critical to the development of new generations of organic materials is the ability to organize them in optimal structures for optical coupling/measurements. We report herein the synthesis of a dodecyl-substituted hexapyrrolohexaazacoronene (C12-HPHAC) displaying discotic liquid crystalline (LC) properties and large Faraday rotation. Thin films with a redox mixed C12-HPHAC/C12-HPHAC+2 composition display a discotic columnar LC phase, are stable to air and moisture in the solid and solution states, and achieve a maximum Verdet constant of 3.36 × 105 deg T–1 m–1 at 700 nm. This result is consistent with Serber’s model of magnetic circular birefringence and displays one of the largest reported Verdet constants for organic materials in the UV–Vis range. The LC phase aligns the molecules and leads to gains in Verdet constants of up to 105% through the favorable orientation of the molecules’ magnetic and electric transition dipole moments with respect to the applied magnetic field.

Critical Sensing Modalities for Hydrogen: Technical Needs and Status of the Field to Support a Changing Energy Landscape

“…Interest in the Faraday effect is exhibiting a resurgence due to the realization that selected organic thin film materials exhibit much higher V M than traditional inorganic crystals . In particular, there may be opportunities to leverage recent results indicating organometallic , and liquid crystalline organic materials exhibit relatively large Faraday effect when oxidized. Alternatively, further optimization of nanoalloy topology may also provide requisite sensitivity.…”

Side-Chain Labeling Strategy for Forming Self-Sorted Columnar Liquid Crystals from Binary Discotic Systems

“…Thus, the construction of thermodynamic bicontinuous structures of electron donor and acceptor materials has been awaited. Liquid crystal (LC) phases are usually thermodynamically stable and appropriate as a platform for constructing the arrays of π-conjugated systems through self-assembly, resulting in the functional soft materials [17][18][19][20][21][22][23]. However, there has been no example of binary LC blends with bicontinuous structures.…”

Using pyrrolizine-fused bipolar PAHs as a new strategy towards efficient red and NIR emissive dyes

“…Nitrogen-doped polycyclic aromatic hydrocarbons (PAHs) that comprise N-pyrrolic fragments at the central or peripheral position of the π-extended structures 1 have recently attracted attention because of their distinctive geometry 2 and selfassembly behaviour, 3,4 their capability to strongly bind fullerenes, 5 their low oxidation potential, 6 and their high-charge carrier mobility. 7 Accordingly, pyrrole, pyrrolo [3,2-b] pyrrole, [2][3][4][5]7 as well as their azacoronene (in neutral or cationic forms) 6,8 and thiepine 7 fused PAH analogues have served as components for application in sensing, 5 photovoltaics, 9 liquid crystals, 6 and single-crystal field effect transistors, 7 respectively. Despite their highly conjugated structure, N-doped PAHs are typically only modestly emissive.…”