A Study of the Structural Effects on the Liquid-Crystalline Properties of Ionic Perylenebis(dicarboximide)s Using UV−Vis Spectroscopy, Polarized Light Microscopy, and NMR Spectroscopy

Abstract

Ionic perylenebis(dicarboximide)s 1-5 were synthesized. The aggregation and liquid-crystalline properties of these compounds in aqueous solutions were investigated. In the concentration range of approximately 5 x 10-7-5 x 10-4 M, the structures of the ammonium side chains and counterions did not have a significant effect on the electronic transition properties and H-aggregate formation of these compounds. However, the liquid-crystalline phase properties varied with the structure of the side chains and the counterions. Ionic perylenebis(dicarboximide)s 1, 3, and 5 with chloride ions formed nematic (N) phases from the isotropic (I) phase, while 2 and 4 with p-methylbenzenesulfonate ions formed chromonic ribbons from the I phase. Studies by polarized light microscopy and 2H NMR spectroscopy indicated that the N phase of 5 (with gem dimethyl groups) formed at higher concentrations than those observed for 1 and 3 at the same temperature. Furthermore, the N phase of 5 was less ordered compared to those of 1 and 3 at a similar concentration and temperature, presumably due to the bulkiness of the side chains of 5 that hindered the stacking and pi-interactions of the aromatic rings.

Characterization of Perylene Diimide Dye Self-Assemblies and Their Use As Templates for the Synthesis of Hybrid and Supermicroporous Nanotubules

“…Self-Aggregation of PDI. The phase behavior of PDI was already reported by Tam-Chang et al 26 PDI forms a chromonicnematic (N) phase from a concentration of about 6 wt %. At higher concentrations, a hexagonal (M) phase was detected.…”

“…26 The molecular structure of PDI is shown in Figure.1. Tetraethyl orthosilicate (TEOS) was purchased from Sigma-Aldrich.…”

Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials

“…464−468 Their detailed studies have shown that the self-assembly properties of these PBIs in water at lower concentrations (5 × 10 −7 to 5 × 10 −4 M) are independent of their ammonium substituents and counterions because all of these PBIs formed H-type aggregates with similar electronic transitions in absorption spectra, while lyotropic LC properties varied with the structural changes in imide substituents and counterions as well. 467 Cationic PBIs 6-7a,c with chloride counterions form nematic phases from the isotropic phase, while PBIs 6-7b,d with tosylate counterions form ribbonlike optical textures. When ethylene unit in ammonium side chains of PBIs 6-7a,c is replaced by a bulky group as in PBI 6-7e, the nematic phase of the latter is formed at higher concentration than those for 6-7a,c at the same temperature ( Figure 63).…”

Multifunctional Optical Thin Films Fabricated by the Photopolymerization of Uniaxially Oriented Lyotropic Liquid Crystal Monomers for Electro-Optical Devices

“…S1) and found in the refs 36, 37, 38. The acrylation reaction between anhydride and alcohol in the presence of 4-dimethylaminopyridine (DMAP) results in the targeted PBRM molecule.…”

“…To realize this concept, a perylene-based reactive mesogenic molecule (abbreviated as PBRM) containing diacrylate functional groups at the ends of the molecule is strategically designed and synthesized363738. The PBRM MOTF is fabricated by the simple shear coating and photopolymerization process.…”