A team of chemists has shown that a single, carefully designed organic molecule can be coaxed into forming seven entirely different crystalline materials, each with its own topology, metal composition and electronic behavior. The work, published in Nature Chemistry by researchers at TU Dresden, the Max Planck Institute of Microstructure Physics, Stockholm University, the University of Cambridge, the University of Hong Kong and their collaborators, demonstrates a form of structural programming in an emerging class of electronic materials known as two-dimensional conjugated metal–organic frameworks, or 2D c-MOFs. These frameworks combine the atomic precision of coordination chemistry with the delocalized electronic states of conjugated organic systems, making them attractive candidates for next-generation semiconductors, sensors, spintronic devices and energy-storage electrodes. Until now, however, the chemist’s ability to dictate exactly how such frameworks assemble has been constrained by a fundamental limitation: the ligand molecules used to build them tend to react uniformly in every direction, producing only one predictable network topology from any given building block.
The new study breaks that limitation through what the researchers call anisotropic reticular chemistry. Reticular chemistry is the design principle behind most modern metal–organic frameworks: rigid molecular building blocks are linked by metal ions into extended, periodic networks whose geometry is dictated by the shape and connectivity of the components. In conventional systems, the ligands are highly symmetric, meaning every reactive site on the molecule behaves identically. When such a ligand meets metal ions in solution, all of its coordinating groups bind in the same way, and the framework that crystallizes is essentially the only one the chemistry allows. The Dresden-led team instead engineered a ligand with deliberately unequal reactivity across its structure: 1,2,5,6,9,10,12,13-octahydroxydibenzo-[fg,op]naphthacene, a large, planar, polycyclic aromatic molecule decorated with eight hydroxyl groups arranged as four catechol units. Catechols, pairs of adjacent hydroxyl groups on an aromatic ring, are classic chelating groups that bind metal ions strongly, but not all catechols on this ligand are created equal.
That inequality is the key to the whole strategy. Because the four catechol sites on the octahydroxy ligand possess different chemical reactivities, influenced by their electronic environment within the fused aromatic core and by the reaction conditions, the researchers could selectively activate some sites while leaving others dormant. When the ligand was combined with copper ions under one set of conditions, only the most reactive catechol pairs participated in coordination, producing a one-dimensional linear chain structure the team labels Cu-1D. Under different conditions, additional catechol sites were engaged, and the ligand stitched together into two-dimensional sheets. Depending on which subsets of sites were activated, the sheets adopted either a square-grid topology, designated Cu-2D-sql, or a honeycomb topology, designated Cu-2D-hcb. Three topologically distinct copper-based frameworks thus emerged from one single-type ligand, something conventional high-symmetry ligands cannot deliver. The structures were solved with remarkable precision using continuous rotation electron diffraction and synchrotron-based single-crystal X-ray diffraction, and the crystallographic data have been deposited with the Cambridge Crystallographic Data Centre.
The most striking demonstration of programmability came from the one-dimensional copper framework. Because Cu-1D retains unreacted catechol sites pointing outward from the linear chains, it behaves as a reactive intermediate rather than a dead end. The researchers found that these dormant sites could be activated in a subsequent step, allowing the introduction of a second metal ion. In a single-crystal-to-single-crystal transformation, a process in which the crystal lattice survives the chemical change intact, the linear chains were cross-linked into two-dimensional square-arranged sheets containing two different metals in defined positions. By choosing the second metal, the team produced four bimetallic frameworks, CuM-2D-sql, where M is nickel, cobalt, zinc or manganese. Each of these materials contains copper and the second metal arranged in an ordered, periodic pattern dictated by the original anisotropic ligand design. This level of control over bimetal node arrangement addresses a long-standing challenge in framework chemistry, where introducing multiple metals usually produces statistical mixtures or phase separations rather than atomically ordered heterostructures.
Why does such atomic-level ordering matter? In bimetallic conductive frameworks, the identity and spatial arrangement of the metal nodes directly shape the electronic band structure, the magnetic interactions and the catalytic properties of the material. Previous studies have shown that alloying different metals into conductive MOFs can continuously tune conductivity, and that heterometallic nanosheets can outperform their single-metal counterparts in both crystallinity and charge transport. But without positional control, it is difficult to attribute property changes to specific structural features or to design them rationally. The new anisotropic strategy turns metal arrangement from an accident of synthesis into a design parameter. The researchers could, in principle, place magnetic ions such as manganese or cobalt at precise intervals within a conducting copper lattice, creating model systems for studying spin ordering in two dimensions, or introduce catalytically active pairs of metals at fixed distances for cooperative electrochemistry.
The electronic consequences of the structural programming were verified through a combination of theoretical modelling and electrical measurements on individual crystals. Density functional theory calculations of the band structures showed that the different topologies and metal compositions produce distinctly different electronic states near the Fermi level, modulating how charge carriers move through the frameworks. The team then fabricated devices from single crystals and measured their charge transport directly, a technically demanding experiment because these framework crystals are small and delicate. The measurements confirmed that the structural variations introduced by anisotropic reticular chemistry translate into measurable changes in charge transport behavior, establishing a clear structure–property relationship across the family of seven materials. Semiconducting behavior, rather than metallic conduction, characterized these frameworks, which is significant for device applications where tunable band gaps and switchable transport are more useful than simple metallic wires.
The synthesis itself involved careful control of coordination chemistry principles that have been understood for decades but rarely combined in this way. The selectivity of metal binding to the different catechol sites reflects differences in their acidity and donor strength, and the researchers monitored the formation of the square-grid and honeycomb copper frameworks using ex situ powder X-ray diffraction, tracking how the crystalline products evolved over the course of the reactions. The single-crystal-to-single-crystal transformation from Cu-1D to the bimetallic sheets was verified crystallographically for each of the four second metals, with independent structure determinations confirming the ordered incorporation of nickel, cobalt, zinc and manganese into the expanding lattice. Computational analysis of reaction energetics and ligand acidity supported the mechanistic picture, explaining why certain catechol sites react first and why particular metal ions are accepted into the remaining coordination sites.
The broader significance of the work lies in what it suggests about the future of framework materials as programmable matter. Reticular chemistry has already given chemists extraordinary control over the pore sizes, shapes and chemical functionality of metal–organic frameworks, enabling applications from carbon capture to drug delivery. Extending that control into the electronic domain, where the exact sequence of metals and the topology of the conducting backbone determine the material’s physics, opens the door to what some researchers have called MOFtronics: electronic devices built from designed crystalline frameworks rather than conventional inorganic semiconductors. Porous field-effect transistors, chemiresistive gas sensors, supercapacitor electrodes and electrocatalysts based on conductive MOFs have all been demonstrated in recent years, and the ability to program both topology and metal ordering from a single ligand should accelerate the rational design of such devices.
There are, of course, challenges ahead. The anisotropic strategy currently relies on a specific, synthetically demanding ligand whose catechol reactivities happen to be distinguishable, and generalizing the approach to other ligand families and metal combinations will require similar molecular engineering. Growing the framework crystals large enough and uniform enough for practical device fabrication remains difficult, as it does for most 2D materials. Nevertheless, the demonstration that seven distinct semiconducting frameworks, spanning one-dimensional chains, two-dimensional square grids, two-dimensional honeycombs and four ordered bimetallic variants, can all be accessed from one molecular building block represents a conceptual advance. It reframes framework synthesis as a programming problem: by encoding unequal reactivity into a ligand, chemists can write different structural outcomes into the same molecule and read them out as different electronic properties. As the vocabulary of such anisotropic building blocks grows, the design space of atomically precise conductive materials expands with it.
Subject of Research: Anisotropic reticular chemistry for programming the topology, metal composition and charge transport of two-dimensional conjugated metal–organic frameworks
Article Title: Programming semiconducting two-dimensional conjugated metal–organic frameworks via anisotropic reticular chemistry
Article References: Zhang, J., Zhou, G., Un, H.-I., Song, J., Petkov, P. S., Iqbal, R., Fu, S., Huang, X., Zhang, G., Lu, Y., Pohl, D., Liu, R., Fu, Y., Li, X., Zhang, W., Rellinghaus, B., Alfonsov, A., Bon, V., Ding, J., … Dong, R. (2026). Programming semiconducting two-dimensional conjugated metal–organic frameworks via anisotropic reticular chemistry. Nature Chemistry. https://doi.org/10.1038/s41557-026-02251-1
Image Credits: AI Generated
DOI: 10.1038/s41557-026-02251-1
Keywords: metal–organic frameworks, reticular chemistry, two-dimensional materials, conjugated frameworks, bimetallic nodes, semiconductors, charge transport, coordination chemistry, crystallography, single-crystal devices, electronic materials, copper catecholate
Cite Scienmag News
APA
MLA
Chicago
Bethany Barker. (September 24, 2026). Chemists Program Crystal Frameworks Atom by Atom with a Single Versatile Molecule. Scienmag. https://scienmag.com/chemists-program-crystal-frameworks-atom-by-atom-with-a-single-versatile-molecule/
Bethany Barker. “Chemists Program Crystal Frameworks Atom by Atom with a Single Versatile Molecule.” Scienmag, 24 September 2026, https://scienmag.com/chemists-program-crystal-frameworks-atom-by-atom-with-a-single-versatile-molecule/. Accessed 24 September 2026.
Bethany Barker. “Chemists Program Crystal Frameworks Atom by Atom with a Single Versatile Molecule.” Scienmag. September 24, 2026. https://scienmag.com/chemists-program-crystal-frameworks-atom-by-atom-with-a-single-versatile-molecule/
Copy citation
Download RIS
Tags: 2D conjugated c-MOFsadvanced coordination chemistry techniquesanisotropic reticular chemistryatom-by-atom crystal designbimetallic nodescharge transportconjugated frameworkscoordination chemistrycopper catecholatecrystallographyelectronic materialselectronic properties of metal-organic frameworksenergy-storage electrode materialsmetal-organic frameworksmolecular topology controlnext-generation semiconductors and sensorsprogrammable crystalline frameworksreticular chemistrysemiconductorssingle-crystal devicesstructural programming in crystalline materialstwo-dimensional materialsversatile organic molecules in materials science
