Luminescent Liquid-Crystalline J‑Aggregate Based on a Columnar Axial Coassembly

TL;DR

Scientists created a new type of glowing liquid crystal by combining two dye-like molecules, enabling precise control over material structures for advanced optical applications.

Contribution

A novel coassembly strategy for creating a two-component columnar liquid crystal with J-type coupling and fluorescence.

Findings

An equimolar mixture of TPE and TPV forms an eight-stranded columnar liquid crystal.

Complementary hydrogen bonding and π–π interactions lead to J-type coupling and fluorescence.

The material exhibits a unique configuration with transition dipole moments aligned along the columnar axis.

Abstract

Controlling
the self-assembly of dyes is essential for designing
functional materials with tailored optical, electronic, and mechanical
properties. However, achieving precise structures from two distinct
chromophores remains a major challenge in the field, requiring sophisticated
strategies to direct their organization at the molecular level. In
the present work, we report a novel approach to engineer complex liquid-crystalline
(LC) columnar nanostructures through the precise coassembly of two
bis-dendronized chromophores: a tris­(p-phenyleneethynylene)
(TPE) dicarboxylic acid (1) and a tris­(p-phenylenevinylene) (TPV) bis­(pyridine) (2). TPE 1 forms an unconventional four-stranded orthogonal columnar
LC phase via hydrogen bonding between carboxylic acid groups, while
TPV 2 adopts a lamellar soft-crystalline phase. Remarkably,
their equimolar mixture (1·2) gives rise to an unprecedented
two-component columnar liquid crystal. This coassembly is grounded
on the complementary hydrogen bonding between pyridine and carboxylic
acid groups that leads to the formation of 1D strands composed of
alternating molecules of 1 and 2. These
strands hierarchically organize by π–π interactions
into eight-stranded columnar structures in which the 1/2 molecules are oriented with the transition dipole
moments parallel to the columnar axis. This configuration promotes
slipped π–π interactions and J-type coupling of
the TPE and TPV components, resulting in a fluorescent LC material.
This work paves the way for the design of precision multicomponent
assemblies, opening exciting avenues for advanced optoelectronic and
photonic materials.

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