Chemistry · Carbon Materials
Carbon has been giving us diamond and graphite for as long as anyone has looked. Theorists said there should be more, and one has just been made.
It is called diamondiyne; it was proposed 35 years ago, and for now it exists in patches ten nanometers wide.
Researchers at the University of Gothenburg, led by Karl Börjesson, have made diamondiyne, a three-dimensional carbon allotrope proposed 35 years ago, in a thin film where two liquids meet using relatively inexpensive equipment. Carbon atoms are joined through triple bonds and crystallize into a network of corner-sharing tetrahedra with voids between them, making it comparable to a porous diamond that, unlike diamond, does not require high pressure to form. Electron microscopy at Stockholm University confirmed the crystal structure only in patches on the film's surface, in repeating patterns within volumes about 10 nanometers on a side that match theoretical models. Its properties and uses have not yet been investigated. Published in Angewandte Chemie International Edition.
Diamondiyne links carbon atoms through triple bonds into a porous network of tetrahedra.
A Carbon Structure Proposed 35 Years Ago Finally Takes Shape
Diamond and graphite have a new carbon cousin called diamondiyne, a structure that was proposed 35 years ago and has now been made in a thin film where two liquids meet.
Researchers at the University of Gothenburg created it for the first time, using relatively inexpensive equipment. It adds a new three-dimensional structure to the forms carbon can take.
The work was published on 14 September 2026 in Angewandte Chemie International Edition, under the title "Diamondiyne: A 3D Carbon Allotrope With Mixed sp–sp3 Hybridization."
The achievement has an important qualifier built in. The crystal structure has so far been confirmed only in microscopic patches, not in a bulk sample you could hold.
So this is proof that the structure can be made, not yet a new material ready to be used.
What a Carbon Allotrope Is
Diamondyne is a carbon allotrope, a form of the element distinguished by how its atoms are arranged.
For many years, the known carbon allotropes were limited to diamond, graphite, and three artificially produced forms: fullerenes, carbon nanotubes, and .
The development of fullerenes and graphene was recognized with Nobel Prizes, largely because the idea that those materials could exist was itself new.
In recent years, researchers have created many additional allotropes. Diamondiyne is the first of this newer group to have a three-dimensional structure.
Diamondiyne's Design: Triple Bonds and Tetrahedra
To create diamondiyne, the researchers joined carbon atoms through triple bonds.
The material crystallizes into a network of tetrahedra, shapes with four triangular faces, connected corner to corner in all three dimensions.
| Feature | Diamondyne, as described |
|---|---|
| Atom linkage | Carbon atoms joined through triple bonds |
| Building block | Tetrahedra connected corner to corner in three dimensions |
| Internal space | Voids between the tetrahedra |
| Formation | Does not require high pressure to bond the carbon atoms |
Karl Börjesson, professor of physical chemistry at Gothenburg and head of the team, says the voids mean the allotrope can be compared to a porous diamond.
The "sp–sp3" in the paper's title refers to two kinds of carbon bonding. As general background, sp carbon atoms sit in the straight triple-bond links, and sp3 carbon atoms are the four-bond, tetrahedral kind found in diamond.
Made Where Two Liquids Meet, Without Extreme Pressure
Börjesson draws a key contrast with diamond: diamondiyne does not require high pressure to make the carbon atoms bond to one another.
That matters because high pressure is what makes diamond synthesis demanding and expensive. A route that skips it could be much more accessible.
The material formed in a thin film at the interface where two liquids meet, using relatively inexpensive equipment.
The source does not name the two liquids, the size of the film, or the yield of diamondiyne, so none of those details are claimed.
What the Microscope Actually Confirmed
Electron microscopy at Stockholm University confirmed the crystal structure, but only in patches on the film's surface.
| Evidence | Detail |
|---|---|
| Method | Electron microscopy at Stockholm University |
| Where confirmed | Patches on the film's surface |
| Size of repeating patterns | A volume about 10 nanometers on each side |
| Match to theory | Images correspond well with the theoretical models |
Börjesson says the team managed to produce repeating patterns of diamondiyne in a volume measuring 10 nanometers on each side, and that the images correspond well with the theoretical models.
Ten nanometers is a tiny region, far smaller than a speck of dust. Repeating order within it is meaningful evidence, but it does not show the whole film, or a bulk crystal, has the structure.
That honest scope is the right way to read the claim: a confirmed structure in patches, with the rest of the film not shown to be diamondiyne.
From COFs to a Theoretical Catalog of Carbon
The discovery grew from a longer effort to make porous materials in which carbon-based molecules bind together without metal ions.
These materials are called covalent organic frameworks, or COFs. They differ from metal-organic frameworks, or MOFs, which combine carbon-based molecules with metal ions, and whose development earned the 2025 Nobel Prize in Chemistry.
A colleague told Börjesson about a website where theoretical chemists had compiled an almost endless list of carbon allotropes that should be possible to make.
Diamondyne's tetrahedral structure had been described theoretically decades before the team succeeded.
Properties, Uses, and Interwoven Structures: What Is Still Unknown
The team says its next step is to investigate the properties of diamondiyne and how it might be used.
The source reports no measurements of hardness, electrical behavior, stability, or any other property, and it names no application. This article therefore claims none.
One idea Börjesson finds exciting is the porous structure. Several diamondiyne structures could potentially be interwoven through each other's voids.
The sensible reading is that diamondiyne is now a real, if tiny, addition to the carbon family, and its practical value remains an open question.
Manohar Insight
What I like about this story is how plainly it admits its limits. The structure is real, but only in patches about 10 nanometers across. Nothing in the source oversells it.
The route is as interesting as the result. A list of theoretically possible carbon forms existed for decades, and this team took one off the shelf and found a way to make it. That suggests a lot of other entries may be makeable too.
The no-high-pressure point is the detail I would watch. Diamond-like frameworks that form under gentle conditions at a liquid interface could be far cheaper to explore than anything needing extreme pressure.
I would resist guessing at uses. The source gives no properties, and carbon allotropes have a history of excitement before the applications become clear. Properties come first.
The interwoven-structure idea is a nice hint of what porosity might allow, but it is a hope, not a result.
The real story is not a new diamond. It is the first three-dimensional member of a newer family of carbon forms, made without extreme pressure and shown, so far, only in the smallest patches.
Join the Signal
If theorists have already listed an almost endless catalog of possible carbon forms, which one would you most want chemists to try to make next? Share your take in the comments.
Discussion