In Memoriam: Professor Helmut Cölfen (1965−2023)

It is difficult to find people who generate such a degree of unanimity around their figures. Prof. Helmut Cölfen was one of them. Admirable for his scientific achievements, but perhaps even more so for his unique character, he was able to create a comforting atmosphere of optimism around him, whether as a mentor, friend, collaborator, or professor. Last November 28th, he passed away due to a long illness, leaving a strange void difficult to accept for those of us who had the opportunity to work with him.

Helmut was educated at the Gerhard Mercator University in Duisburg, Germany. There he obtained his PhD degree in Chemistry in 1993 with summa cum laude distinction for his work on the study of polymer gels by Analytical Ultracentrifugation. This technique would become his greatest passion. Helmut would extend its use beyond its usual use, mainly in the study of polymers, DNA, and proteins, to the characterization of nucleation processes and colloidal nanoparticles. His inventiveness and appetite for generating scientific knowledge were characteristic of his career, leading him to open up new fields of research. From 1995, working as a group leader at the Max-Planck Institute for Colloids and Interfaces, he focused his attention on the study of biomineralization processes and the use of polymers to control them. Helmut pioneered the use of the «mesocrystal» concept. He did so after identifying the existence of crystals formed through the assembly of nanoparticles showing a long-range orientation at the atomic level. He was also a pioneer in the characterization of pre-nucleation clusters, key to understanding non-classical nucleation mechanisms in materials such as calcium carbonate. These studies were fundamental for Helmut to receive, shortly before his death, the prestigious ERC Synergy Grant, with the purpose of unraveling the role played by minerals in the emergence of primordial life. This honor, together with others such as the Liesegang Prize of the German Colloid Society, is testimony to the quality of his scientific work.

In 2010, Helmut settled at the University of Konstanz, Germany, as a Professor of Physical Chemistry. From there, he expanded his research on the development of polymers for the fabrication of dental implants or the self-assembly of colloidal nanoparticles into mesocrystalline structures. His efforts to exploit the potential of Analytical Ultracentrifugation led him to the implementation of multi-wavelength detectors. He thus added a spectral dimension to the study of complex colloidal systems, allowing an unprecedented degree of characterization to be achieved. It was, in fact, access to such a powerful technique in the field of colloids, one of the reasons that led me to join his group as a postdoctoral fellow in 2019. The most important reasons, however, were his affable character, passion for science, and modesty. Despite all his accomplishments, he always had an exemplary attitude and sensitivity. Not surprisingly, he was one of the most beloved professors in the chemistry department.

I would like to acknowledge and thank you for your legacy, Prof. Helmut. Many of us owe you a large part of who we are. I would like to conclude with the words that your group dedicated to you, reflecting the feelings of those of us who had the honor of knowing you.

Helmut, your warm nature and your inexhaustible optimism shaped the working group and will live on in our memories. Thank you for your trust in each and every one of us and the freedom you gave us. Your loss weighs heavily, as we have not only lost an outstanding researcher and mentor, but above all an extraordinary, warm-hearted person and leader of our band. You leave behind a deep void.