[Paper Review] Self-assembled Frameworks Solid with Turbostratic Stacked Crystalline Layers -- A Frustrated 3D Crystal Lattice

H.-M. Qin, Jiahui Wang+3 more|arXiv (Cornell University)|Jun 16, 2023

Advanced ceramic materials synthesisMaterials Science3 citations

TL;DR

This study introduces a self-assembled 3D framework material with turbostratic stacking of crystalline layers, achieving a frustrated crystal lattice by weakening interlayer interactions to ~1/60 of graphite's strength. The resulting material exhibits long-range order with controlled disorder, offering a new route to engineer intermediate states between crystals and glasses.

ABSTRACT

Solid materials possess both long-range order and some degree of disorder are critical for understanding the nature of crystal and glassy state, but how to controllable introduce specific type of disorder into a crystalline material is a big challenge. Our previous work indicated that weakening the inter-layer interaction is an effective strategy to import disorders between the layers.Here, we illustrated that the inter-layer interaction can be weakened to around 1/60 of that of graphite in the self-assembled material, a two-dimensions frameworks formed by B-C-T-A with Cu nodes, which has an obvious layered-structure.

Motivation & Objective

• To understand the nature of solid materials that combine long-range order with controlled disorder.
• To address the challenge of controllably introducing specific types of disorder into crystalline frameworks.
• To explore how interlayer interactions govern structural frustration in 2D-like frameworks with 3D connectivity.
• To develop a strategy for stabilizing metastable, disordered crystalline states through engineered interlayer weakening.

Proposed method

• Synthesis of a self-assembled metal-organic framework using B-C-T-A ligands and Cu nodes to form a layered 2D framework with 3D connectivity.
• Employing X-ray diffraction and electron microscopy to characterize the turbostratic stacking of crystalline layers.
• Measuring interlayer interaction strength via structural and thermodynamic analysis, showing a reduction to ~1/60 of graphite's value.
• Analyzing the crystal lattice for signs of frustration, including rotational misalignment and lack of long-range in-plane periodicity.
• Using computational modeling to correlate weak interlayer coupling with the emergence of frustrated 3D order.
• Comparing structural features with known layered materials to isolate the role of interlayer interaction strength.

Experimental results

Research questions

• RQ1 How can interlayer interactions be systematically weakened in a 2D framework to induce controlled disorder?
• RQ2 What structural signatures define a frustrated 3D crystal lattice in a self-assembled framework?
• RQ3 To what extent does turbostratic stacking disrupt long-range order while preserving local crystallinity?
• RQ4 Can a metastable, disordered crystalline state be stabilized in a 3D framework through ligand design and metal node coordination?
• RQ5 What is the quantitative relationship between interlayer interaction energy and the degree of lattice frustration?

Key findings

• The interlayer interaction energy in the self-assembled framework is reduced to approximately 1/60 of that in graphite, indicating a highly weakened coupling between layers.
• The material exhibits a turbostratic stacking arrangement, where crystalline layers are rotated relative to one another, disrupting long-range periodicity.
• Despite the lack of long-range in-plane order, local crystallinity is preserved, indicating a distinct intermediate state between crystal and glass.
• The 3D framework maintains structural integrity and long-range connectivity through Cu-node coordination, stabilizing the disordered architecture.
• The system demonstrates a frustrated 3D crystal lattice, where competing interactions prevent full ordering while preserving local order.
• The observed structural features suggest a new class of materials with tunable disorder, bridging the gap between crystalline and amorphous states.