Molecular Borromean Rings Molfidget

Molecular Borromean Rings — All-Atom 3D Printable Model

This is an all-atom 3D-printable model of the molecular Borromean rings, designed using Molfidget.

Borromean rings are a topological structure consisting of three interlocked rings. No two rings are directly linked as a pair, yet the three rings cannot be separated unless one of them is broken or removed. This model represents the molecular version of this topology: a mechanically interlocked molecular architecture reported by Stoddart and co-workers in 2004.

The original molecular Borromean rings were reported in:

Kelly S. Chichak, Stuart J. Cantrill, Anthony R. Pease, Sheng-Hsien Chiu, Gareth W. V. Cave, Jerry L. Atwood, and J. Fraser Stoddart,
“Molecular Borromean Rings,” Science 304, 1308–1312, 2004. DOI 

Model Features

This model is intended as a hands-on molecular model of a mechanically interlocked molecule. The three macrocyclic rings are printed in different colors so that the Borromean topology can be recognized easily from multiple viewing angles.

The model is useful for teaching and demonstrating molecular topology, mechanically interlocked molecules, supramolecular chemistry, and the relationship between molecular structure and knot theory.

Most bonds in the model are rotatable, following the Molfidget design concept. The coordination of the rings to six Zn ions is represented using embedded magnets, corresponding to the metal-templated precursor complex. Removing the ion parts gives a flexible model of the molecular Borromean rings.

Print Profile

The model is divided into three color-coded rings. Printing each ring in a different color makes the interlocked structure much easier to understand visually.

Recommended color scheme:

Red ring
Green ring
Blue ring

White atoms are used for hydrogen atoms in the model.

Magnets and Assembly

You will need 30 disc-shaped neodymium magnets:

Diameter: 6 mm
Thickness: 2 mm

Use a small amount of gel-type super glue to secure the magnets in the designated holes. Before gluing, carefully check the magnetic polarity. The magnets should attract each other at the coordination sites. If one magnet is inserted with the wrong polarity, the corresponding coordination interaction will repel instead of attract.

Additional Information

My article about this model, in Japanese: [link]

If you’d like to design and 3D-print your own molecules, give molfidget a try! Visit its GitHub repository to download the tool and explore the installation instructions:

https://github.com/longjie0723/molfidget/

Molfidget is a Python program that allows you to effortlessly create molecular models for 3D printing. It offers the following features:

• Rotatable single bonds: You can change the molecule’s three-dimensional conformation by rotating along single bonds.
• Simple input for common file formats: Just provide a standard molecular file format (such as .mol or .pdb), and it generates a file ready for 3D printing of your chosen molecule.
• Integrated rotating axes: The model is produced as a single piece including the rotation axes, making it capable of representing complex molecular structures.
• Versatile usage: It’s perfect for scientific research and educational purposes—and it's also fun to fidget with, making it an interactive toy-like molecular model.