Pyrrole- and polypyrrole-based liquid crystals

Abstract

In this paper we report one of the first examples of a soluble, fusible liquid crystalline polypyrrole. We describe the synthesis and characterisation of two pyrrole-based monomers substituted at the N-position with the mesogenic group 4-cyanobiphenyl. The mesogenic group is separated from the pyrrole moiety by an alkyl chain of either 3 or 11 methylene units length. We discuss the spectroscopic and thermotropic properties of these monomers and describe their oxidative polymerisation using electrochemical methods and separately using FeCl 3 and I 2 as chemical oxidants.

Pyrrole and polypyrrole-based liquid crystals containing azobenzene mesogenic groups

“…12,18 For the conductivity measurements, pellets (1 cm diameter) were prepared of the polymers by pressing the sample (ca. 50 mg) under 5 ton for 30 min.…”

“…The syntheses of the a-bromo-v-[4-(4'-substituted phenylazo)phenyloxy]alkanes have been described in detail elsewhere. [14][15][16] The N-{v-[4-(4'-substituted phenylazo)phenyloxy]alkyl}pyrroles were prepared using a modification 12 Polymer synthesis (a) Chemical polymerisation using iron chloride. The monomer (0.001 mol) in chloroform (5 ml, freshly distilled) was added dropwise to a suspension of anhydrous FeCl 3 (0.113 g, 0.7 mol) in chloroform (50 ml, freshly distilled) under nitrogen.…”

Superlong Polypyrrole Nanowires Aligned within Ordered Mesoporous Silica Channels

“…Although certain shifts of the IR bands towards higher wavenumbers were observed, these new adsorption peaks were quite similar to the typical set of bands characteristic for PPy. [14,21] Additionally, the absorbance at 723 cm À1 (Figure 2 A), attributed to the a-(CÀH) bending mode of the pyrrole ring, is absent in the polymer, indicating that a-a coupling of the pyrrole units occurred [22] and conjugated PPy was formed in the channels.…”

Design of Neutral Metallomesogens from 5,5‐Dimethyldipyrromethane: Metal Ion Mediated Control of Folding and Hairpin Structures

“…[26] The second group are the calamitic, monomeric, N-substituted pyrroles that are subsequently polymerised to form poly(pyrrole) backbones. [27][28][29][30] There are naturally a few exceptions that fall outside these two categories, such as derivatives of diketopyrrolopyrroles [31] which display nematic and smectic A phases. Similarly, 2-substituted monomeric pyrroles [32,33] can display nematic phases both as the free ligand and as the bis complexes with Ni II and Cu II ions.…”