What question did this study set out to answer?

To explore the host–guest chemistry of amorphous red phosphorus and its interactions with cyclodextrin.

January 20, 2026Small0 citations

Amorphous Red Phosphorus: Host–Guest Assembly with Cyclodextrin

JZJiulong ZhouSouthwest Jiaotong University LYLifeng YaoSouthwest Jiaotong University SZSong ZhangSouthwest Jiaotong University

Key Points

To explore the host–guest chemistry of amorphous red phosphorus and its interactions with cyclodextrin.
Synthesis of pseudo-polyrotaxanes using α- and β-cyclodextrin with amorphous red phosphorus.
Characterization through nuclear magnetic resonance spectroscopy and atomic force microscopy.
Assessment of mechanical properties through single-molecule force spectroscopy.
β-cyclodextrin successfully threads ARP, enhancing its water solubility.
α-cyclodextrin requires structural distortion before partial assembly with ARP.
Increasing CD coverage improves the mechanical stiffness of ARP chains.

Abstract

ABSTRACT Amorphous red phosphorus (ARP) has recently been identified as a zig‐zag ladder polymer, yet its function beyond a low‐cost phosphorus source remains unexplored. Here we report the first host–guest chemistry of ARP. In water, hydrophobic ARP threads through α ‐ or β ‐cyclodextrin (CD) to produce water‐soluble pseudo‐polyrotaxanes, as evidenced by nuclear magnetic resonance (NMR) spectroscopy, atomic force microscopy (AFM) imaging and AFM‐based single‐molecule force spectroscopy (SMFS). β ‐CD, whose cavity diameter (0.60 nm) matches the 0.582 nm van‐der‐Waals width of ARP, assembles readily with ARP; α ‐CD, which has a smaller cavity, requires conformational distortion before assembly, producing only ∼30% fully threaded chains even after 10 days. Threading converts collapsed ARP globules into extended chains whose mechanical stiffness increases with CD coverage. After assembly with β ‐CD, the water solubility of ARP can be significantly enhanced, which builds a method to tune the hydrophilicity of an inorganic polymer chain without the need for traditional chemical modification. This work establishes ARP as an inorganic building block for supramolecular assembly, opening routes to phosphorus‐based functional materials.

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