Scientists unlock new glass properties using molecular modification technique

A team of researchers across four universities—TU Dortmund, Paderborn, Duisburg-Essen, and Oxford—has cracked a problem that has long constrained what glass can do. They've found a way to chemically rewrite the internal structure of glass while it's still being made, using a molecule called 1,10-phenanthroline. The result is glass with properties that were previously out of reach: materials that can be magnetic, that can emit light, that can do things ordinary glass cannot.

The breakthrough hinges on understanding what happens when glass forms. Normally, when molten material cools rapidly, the atoms freeze in place without arranging themselves in any orderly pattern. Whatever chemistry the starting material possessed is essentially locked in. Researchers had to work with what they were given. But the team, led by Prof. Sebastian Henke at TU Dortmund, discovered that this doesn't have to be the case—at least not when working with glasses derived from metal-organic frameworks, or MOFs. These materials consist of metal centers held together by organic compounds, and their structure can be fundamentally altered while still in liquid form.

The phenanthroline molecule does two things at once. First, it acts as a flux, lowering the temperature at which the material melts. Second, and more importantly, it enters into a chemical reaction with the metal atoms. As the material heats, the phenanthroline binds directly to the metal centers and displaces some of the existing bonds. This changes what scientists call the coordination environment—essentially, how many neighboring atoms surround each metal atom. Because the new molecule bonds more strongly to the metal centers, the number of neighbors increases, triggering a complete restructuring of the glass network. By controlling how much phenanthroline is added, researchers can control how extensively this restructuring occurs.

The practical benefits are substantial. Many materials that researchers want to turn into glass would normally decompose before reaching the necessary temperature. Extreme heat destroys their structure and introduces unwanted impurities that mask the very properties researchers are trying to create. By lowering the melting point, the gentler process keeps the material stable. In studies of cobalt-containing glasses, the team found that this approach prevented the formation of harmful decomposition products—the only way to detect the pure magnetic effects that would otherwise have been hidden.

Proving the structure had actually changed required sophisticated measurement techniques. Conventional X-ray methods don't work well here because the resulting glass no longer has a regular crystal structure. Instead, the team used X-ray absorption spectroscopy to examine the immediate surroundings of the cobalt atoms. The data confirmed what they predicted: while the atoms maintained their chemical state, their spatial environment shifted significantly. The bonds to neighboring molecules adapted to accommodate the new molecule.

The technique isn't limited to a single class of materials. The researchers successfully applied their method to carboxylate-based scaffold structures as well, expanding the range of glasses that can be modified this way. Prof. Henke describes the significance plainly: the molten state is no longer simply an intermediate step between solid and liquid. It becomes a reaction space where the structure can be deliberately programmed. This control opens new possibilities. Organometallic glasses could eventually be used in catalysis, as sensors, or in optoelectronics—applications where precise control over light, magnetism, or chemical reactions is essential. The metal centers can now be specifically manipulated in ways that were previously impossible, creating pathways for components that don't yet exist.