A carbon structure first proposed more than three decades ago has now been produced experimentally by researchers at the University of Gothenburg, Sweden.
The material, called diamondiyne, is a three-dimensional carbon allotrope with a porous structure resembling that of diamond. Until recently, its existence had been predicted only through theoretical models.
The research team successfully formed diamondiyne in a thin film at the interface between two liquids, using relatively inexpensive laboratory equipment. Electron microscopy subsequently revealed small crystalline regions whose atomic arrangements closely matched the predicted structure.
The findings, published in Angewandte Chemie International Edition, provide experimental evidence that this previously theoretical form of carbon can be synthesised.
๐ ๐๐๐ฐ ๐๐๐ฆ๐๐๐ซ ๐จ๐ ๐ญ๐ก๐ ๐๐๐ซ๐๐จ๐ง ๐ ๐๐ฆ๐ข๐ฅ๐ฒ
Carbon is unusual because its atoms can bond in several ways, producing materials with remarkably different structures and properties.
These structural forms are known as allotropes.
Diamond and graphite are among the best-known examples. Both consist entirely of carbon atoms, yet their atomic arrangements give them very different physical characteristics.
In diamond, carbon atoms form a rigid three-dimensional network, making it exceptionally hard. Graphite, by contrast, consists of layers of carbon atoms that can slide over one another.
Other recognised carbon allotropes include fullerenes, carbon nanotubes and graphene.
Diamondiyne adds another structural arrangement to this family.
Its framework consists of interconnected tetrahedral units, with spaces between them that create a porous three-dimensional network.
๐๐ก๐๐ญ ๐๐๐ค๐๐ฌ ๐๐ข๐๐ฆ๐จ๐ง๐๐ข๐ฒ๐ง๐ ๐๐ข๐๐๐๐ซ๐๐ง๐ญ?
Diamondiyne is distinguished by the way its carbon atoms are connected.
The material contains carbon bonds associated with mixed spโspยณ hybridisation, including triple-bonded carbon units that link the framework.
These connections produce a network of tetrahedra extending in three dimensions.
A tetrahedron is a geometric structure with four triangular faces. In diamondiyne, the tetrahedral units connect at their corners, leaving open spaces within the material.
This arrangement gives diamondiyne a porous architecture.
Professor Karl Bรถrjesson, who led the research team at the University of Gothenburg, described the structure as comparable to a porous diamond.
An important difference is that diamondiyne can be formed without the high pressures associated with producing certain diamond structures.
๐ ๐ซ๐จ๐ฆ ๐ ๐๐ก๐๐จ๐ซ๐๐ญ๐ข๐๐๐ฅ ๐๐ซ๐๐๐ข๐๐ญ๐ข๐จ๐ง ๐ญ๐จ ๐ ๐๐๐๐ฅ ๐๐๐ญ๐๐ซ๐ข๐๐ฅ
The possibility of diamondiyne was first proposed approximately 35 years before its experimental synthesis.
Theoretical chemists had predicted numerous possible carbon allotropes by examining different ways carbon atoms could form stable networks.
Among these proposed structures was diamondiyne, with its distinctive three-dimensional tetrahedral arrangement.
However, predicting a structure does not guarantee that it can be produced experimentally.
The challenge lies in directing carbon atoms to form the required bonds and assemble into the intended configuration.
For diamondiyne, achieving that arrangement proved difficult.
Bรถrjesson and his colleagues spent years investigating approaches that might allow the structure to form.
Their eventual success provides experimental support for a carbon architecture that had previously existed only in theoretical descriptions.
๐๐จ๐ฐ ๐ญ๐ก๐ ๐๐๐ฌ๐๐๐ซ๐๐ก๐๐ซ๐ฌ ๐๐ซ๐จ๐๐ฎ๐๐๐ ๐๐ข๐๐ฆ๐จ๐ง๐๐ข๐ฒ๐ง๐
The research team developed a method for forming the carbon framework within a thin film at the boundary between two liquids.
This interface provided the environment in which the molecular components could react and form the desired connections.
The approach did not require the high-pressure conditions commonly associated with certain forms of diamond synthesis.
It also relied on relatively inexpensive laboratory equipment.
Nevertheless, forming the intended crystal structure remained challenging.
During synthesis, competing reactions and structural irregularities could prevent carbon atoms from assembling into the predicted diamondiyne framework.
As a result, the researchers did not obtain a large, continuous diamondiyne crystal.
Instead, they identified small regions within the film where the desired repeating structure had formed.
๐๐ฅ๐๐๐ญ๐ซ๐จ๐ง ๐๐ข๐๐ซ๐จ๐ฌ๐๐จ๐ฉ๐ฒ ๐๐จ๐ง๐๐ข๐ซ๐ฆ๐๐ ๐ญ๐ก๐ ๐๐ซ๐ฒ๐ฌ๐ญ๐๐ฅ๐ฅ๐ข๐ง๐ ๐๐๐ญ๐ญ๐๐ซ๐ง
To investigate the material's structure, the researchers used electron microscopy at Stockholm University.
The observations revealed repeating crystalline patterns within small regions of the film.
These patterns closely corresponded to the theoretical models of diamondiyne.
According to Bรถrjesson, the team successfully produced ordered regions measuring approximately 10 nanometres along each dimension.
A nanometre is one-billionth of a metre, meaning the observed crystalline regions were extremely small.
Although the ordered structure was limited to microscopic patches, the agreement between the experimental images and theoretical predictions provided evidence that diamondiyne had formed.
The result represents an important experimental step, while also showing that producing larger and more uniform structures remains a challenge.
๐๐ก๐ ๐๐จ๐ง๐ง๐๐๐ญ๐ข๐จ๐ง ๐ญ๐จ ๐๐จ๐ฏ๐๐ฅ๐๐ง๐ญ ๐๐ซ๐ ๐๐ง๐ข๐ ๐ ๐ซ๐๐ฆ๐๐ฐ๐จ๐ซ๐ค๐ฌ
The discovery emerged from the team's broader research into covalent organic frameworks (COFs).
COFs are materials formed when organic molecular building blocks are connected through covalent bonds to produce extended structures.
Researchers are interested in these frameworks partly because their molecular arrangements can create ordered pores.
Unlike metal-organic frameworks (MOFs), which contain metal ions or clusters connected by organic linkers, COFs can be constructed without metal ions.
The development of metal-organic frameworks was recognised by the 2025 Nobel Prize in Chemistry.
Bรถrjesson's research group had been investigating ways to create porous frameworks through carbon-based molecular connections.
That work provided a foundation for their efforts to synthesise diamondiyne.
๐๐ก๐ฒ ๐ ๐๐จ๐ซ๐จ๐ฎ๐ฌ ๐๐๐ซ๐๐จ๐ง ๐๐ญ๐ซ๐ฎ๐๐ญ๐ฎ๐ซ๐ ๐๐ฌ ๐๐ง๐ญ๐๐ซ๐๐ฌ๐ญ๐ข๐ง๐
One of diamondiyne's most distinctive features is the presence of voids within its three-dimensional framework.
These spaces arise from the arrangement of interconnected tetrahedral units.
The resulting structure differs from the densely connected carbon network found in conventional diamond.
Porous materials are an important area of materials research because their internal architecture can influence how they interact with other substances.
However, the practical properties of diamondiyne have not yet been established.
The researchers plan to investigate its physical and chemical behaviour before determining whether the material has useful applications.
๐๐จ๐ฎ๐ฅ๐ ๐๐ข๐๐ฆ๐จ๐ง๐๐ข๐ฒ๐ง๐ ๐ ๐จ๐ซ๐ฆ ๐๐ง๐ญ๐๐ซ๐ฐ๐จ๐ฏ๐๐ง ๐๐ญ๐ซ๐ฎ๐๐ญ๐ฎ๐ซ๐๐ฌ?
The porous architecture raises another question about how diamondiyne frameworks might interact.
Bรถrjesson suggested that multiple diamondiyne structures could potentially become interwoven, with one framework extending through the voids of another.
Such arrangements would introduce additional structural possibilities beyond the individual diamondiyne network.
For now, this remains a subject for further investigation.
The research team must first establish more reliable methods for producing the material and characterising its properties.
๐๐ก๐๐ญ ๐ญ๐ก๐ ๐๐ข๐ฌ๐๐จ๐ฏ๐๐ซ๐ฒ ๐๐๐๐ง๐ฌ ๐๐จ๐ซ ๐๐๐ซ๐๐จ๐ง ๐๐ก๐๐ฆ๐ข๐ฌ๐ญ๐ซ๐ฒ
The experimental production of diamondiyne expands the range of known carbon structures.
For much of the history of materials science, diamond and graphite were the most familiar forms of elemental carbon.
The discovery and development of fullerenes, carbon nanotubes and graphene later demonstrated that carbon could form several other stable architectures.
These advances transformed research into carbon-based materials and contributed to Nobel Prize-winning discoveries.
Diamondiyne represents another step in exploring the structural possibilities of carbon.
Its synthesis is particularly significant because it provides experimental evidence for a three-dimensional carbon framework that had remained theoretical for decades.
๐๐ก๐๐ญ ๐๐จ๐ฆ๐๐ฌ ๐๐๐ฑ๐ญ?
Although the researchers have identified crystalline diamondiyne regions, several questions remain unanswered.
The material has so far been confirmed only in small patches, rather than as a large, continuous crystal.
Further work will be needed to understand the factors that influence its formation and to develop methods for producing larger, more uniform samples.
The team also intends to investigate diamondiyne's properties and assess whether its porous structure offers useful characteristics.
Another area of interest is the possibility of forming interwoven diamondiyne frameworks.
These investigations will help determine whether diamondiyne can move beyond laboratory-scale structural confirmation towards broader materials research.
๐ ๐๐ก๐๐จ๐ซ๐๐ญ๐ข๐๐๐ฅ ๐๐๐ซ๐๐จ๐ง ๐๐ญ๐ซ๐ฎ๐๐ญ๐ฎ๐ซ๐ ๐๐๐๐จ๐ฆ๐๐ฌ ๐๐ฑ๐ฉ๐๐ซ๐ข๐ฆ๐๐ง๐ญ๐๐ฅ ๐๐๐๐ฅ๐ข๐ญ๐ฒ
After approximately 35 years as a theoretical prediction, diamondiyne has been produced experimentally.
Researchers at the University of Gothenburg formed the material in a thin film between two liquids, while electron microscopy at Stockholm University identified small crystalline regions consistent with its predicted three-dimensional structure.
The findings establish an experimental basis for studying a porous carbon allotrope built from interconnected tetrahedral units and mixed spโspยณ bonding.
Although the material has not yet been produced as a large, uniform crystal, the successful identification of its ordered structure provides a foundation for further research.
The next challenge is to improve its synthesis, investigate its properties and determine whether its unusual architecture can support practical applications.
๐๐จ๐ฎ๐ซ๐ง๐๐ฅ ๐๐๐๐๐ซ๐๐ง๐๐
Yizhou Yang, Jie Xu, Yanyan Chen, Yu Xia, Sami Zeliouche, Clara Schรคfer, Martin Ratsch, Ebba Matic, Martin Rahm, Lars Evenรคs, Angela Beth Grommet, Tom Willhammar and Karl Bรถrjesson.
โDiamondiyne: A 3D Carbon Allotrope With Mixed spโspยณ Hybridization.โ
Angewandte Chemie International Edition, 14 September 2026.