Computational Modeling and Self-Assembly Synthesis of Borazine-Based Free-Standing Molecular-Thin Films

TL;DR

Researchers developed a method to create borazine-based thin films using computational modeling and experimental techniques, enabling the formation of free-standing molecular-thin films.

Contribution

A dual theoretical and experimental protocol for synthesizing borazine-based thin films, validated by successful free-standing film formation.

Findings

π–π stacking interactions drive bilayer film formation with 2.1 nm thickness.

The Langmuir–Blodgett technique successfully fabricated free-standing films spanning 0.6 μm diameter holes.

The film retains hexagonal-based π–π stacking and crystal-like features of borazine.

Abstract

Boron-nitride-rich organic thin materials based on borazines
have
gained significant attention for their potential in nano­(opto)­electronic
and energy storage devices. We address synthetic challenges in producing
effective borazine-based thin films by proposing a dual theoretical
and experimental protocol. This combines a multiscale computational
approach, using density functional theory and classical molecular
dynamics, with synthesis and thin-film formation via the Langmuir–Blodgett
technique. The computational modeling focuses on three key properties:
π–π stacking interactions, molecular steric hindrance,
and dynamic self-assembly orientation. This modeling guided the selection
of a borazine molecular building block and enabled the successful
experimental formation of a free-standing molecular-thin borazine-based
film. Solely π–π stacking interactions were found
to drive the formation of a bilayer film with a molecular thickness
of 2.1 nm, capable of spanning 0.6 μm diameter holes as a free-standing
film. The agreement between theory and experiment confirms that the
film retains essential features of the borazine molecular crystal,
particularly intermolecular offset face-to-face π–π
stacking and hexagonal-based pattern orientations. We thus establish
a robust and transferable approach for modeling and synthesizing borazine-based
thin materials, deepen the understanding of molecular interactions
in borazine self-assembly, and demonstrate the suitability of the
Langmuir–Blodgett technique for fabricating borazine-based
2D materials.

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