A collaborative study between the group of Prof. José A. Berrocal at ICIQ, and Prof. Laura Baldini at the University of Parma (Italy) reports a new calixarene-based mechanoluminophore. Published in Angewandte Chemie International Edition, the work shows how mechanical force can reversibly modify a molecular conformation and produce a visible fluorescence change.
The researchers designed a flexible calixarene functionalised with pyrene units acting as fluorescent probes. In its relaxed state, the molecule forms intramolecular excimers that emit green-yellow light under UV irradiation. When mechanical force is applied (for example, by stretching a polymer film containing these molecules covalently incorporated) the excimer interaction is disrupted, shifting the emission to blue. This process is reversible over multiple cycles.
This behaviour is enabled by the calixarene scaffold, which keeps the fluorophores in close proximity while allowing temporary separation under mechanical stress. By embedding these systems into polymer matrices, macroscopic deformation can be translated into a measurable optical signal.
Learning from the first author, Dr. Lucia Visieri
What is the importance of this discovery?
The key point is that we show, for the first time, that mechanical force can be used to control the conformation of a flexible calixarene. This essentially turns a classic macrocycle into a new structural motif for designing mechanosensitive materials. The calixarene is particularly advantageous as it plays a dual role: its preorganised structure promotes interactions between functional groups at the upper rim, while its intrinsic flexibility enables a reversible response, an important and still challenging feature in mechanochemistry.
What was your role in the research?
I feel closely connected to this project as I was involved at every stage, from the initial molecular design, through the (sometimes challenging) synthesis of the calixarene, to developing the material and making the system work in practice.
What has this meant to you?
The publication represents an important milestone, as it brings together the core focus of my PhD, calixarene chemistry, with a new direction in mechanoresponsive materials. It also opens the path to an entirely new research line, especially focused on reversible systems designed for long‑term use and more sustainable material concepts.
Reference publication
Mechanically Activated Luminescence in Polyurethanes Incorporating Calixarene Mechanophores
Visieri, L.; Casnati, A.; Baldini, L.; Berrocal, J. A.
Angew. Chem.-Int. Edit. 2026, e9927716
DOI: 10.1002/anie.9927716
La entrada New mechanoluminophore based on calixarenes enables reversible optical response to mechanical force se publicó primero en ICIQ.