# Poly(pyridinium salt)s Containing 9,9-Bis(4-aminophenyl)fluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties

## TL;DR

This paper introduces new poly(pyridinium salt)s with light-emitting and liquid-crystalline properties, synthesized using specific chemical methods and tested for their optical and structural behaviors.

## Contribution

The novelty lies in the synthesis and characterization of non-conjugated polyelectrolytes with both lyotropic liquid-crystalline and light-emitting properties.

## Key findings

- The polymers exhibited lyotropic liquid-crystalline phases confirmed by POM and SAXS.
- They showed greenish-yellow light emission in polar solvents and blue-shifted emission upon aggregation.
- Polyelectrolytic behavior was observed in dimethyl sulfoxide.

## Abstract

Main-chain conjugated and non-conjugated polyelectrolytes are an important class of materials that have many technological applications ranging from fire-retardant materials to carbon-nanotube composites, nonlinear optical materials, electrochromic materials for smart windows, and optical sensors for biomolecules. Here, we describe a series of poly(pyridinium salt)s-fluorene containing 9,9-bis(4-aminophenyl)fluorene moieties with various organic counterions that were synthesized using ring-transmutation polymerization and metathesis reactions, which are non-conjugated polyelectrolytes. Their chemical structures were characterized by Fourier transform infrared (FTIR), proton (1H) and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers, and elemental analysis. They exhibited polyelectrolytic behavior in dimethyl sulfoxide. Their lyotropic liquid-crystalline phases were examined by polarizing optical microscopy (POM) and small angle X-ray scattering (SAXS) studies. Their emission spectra exhibited a positive solvatochromism on changing the polarity of solvents. They emitted greenish-yellow lights in polar organic solvents. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), whose λem peaks were blue shifted.