Josef Holzwarth, the fastest scientist

November 12, 2020
The well-known fast reaction kinetics researcher has sadly passed away at the age of 78. A few memories from inside and outside the Fritz Haber Institute.

While scientists frequently come and go at the Fritz Haber Institute (FHI), some researchers spend their entire academic career at the Institute, providing the FHI with continuity. One of these long-term-FHI researchers was Josef Holzwarth, who sadly passed away on 26th October 2019 at the age of 78. Josef Holzwarth, known as “Sepp” to his German friends and colleagues, studied Chemistry at the Technical University in Munich. After the completion of his PhD, he moved to the FHI with his supervisor Prof. Heinz Gerischer, where he remained until his retirement in 2005 – 35 years in total.

“Sepp was a highly gifted physical chemist who performed world-class research in fast reaction kinetics,” says Alex Bradshaw, a former Director at the FHI. At the Fritz Haber Institute, Holzwarth further developed a kinetic technique he studied during his PhD: a novel continuous-flow method where fast electron-transfer reactions in solution were observed along the direction of flow. This extended the time range down to a few microseconds. He came to be a leader in the development of fast reaction methods throughout his research career. “Josef thought about scientific problems with a ‘kinetics lens’. To solve his scientific questions, he developed and implemented techniques to measure kinetics that span time scales from picoseconds to seconds,” says Prof. Cornelia Bohne, Department of Chemistry, University of Victoria (Canada). He developed a new temperature jump method using an iodine laser, which offered a wider range of application than the standard technique at the time, extending down into the sub-nanosecond range.

But not only did Holzwarth develop the method, he also excelled at building the necessary apparatus. Prof. Laurie Peter, Department of Chemistry, University of Bath (UK), a personal friend and colleague of Holzwarth’s at the FHI from 1970-1975, remembers this time well. “Sepp was a great tea drinker, and we often discussed science, politics and life over a good cup of Darjeeling. After one of our tea sessions, I was privileged to be present at the demonstration of his newly built iodine laser, an experience that turned out to be more exciting than either of us had expected. The flash lamps were fired by discharging an enormous bank of capacitors using a switch powered by compressed air. When Sepp fired the laser, an ear-splitting bang followed, because the capacitors discharged not to the lamps but to the metal window frame! Having survived this electrifying experience, we stayed in touch after I returned to the UK, and he visited us several times in Southampton when he was over working with Brian Robinson.”

Brian Robinson, Emeritus Professor of Chemistry, University of East Anglia (UK) still holds Holzwarth’s iodine laser in high esteem. “It was a unique instrument”, he says. “It would undoubtedly have been widely copied but for its complexity and cost. It was impressive – in order to minimise electrical noise, the laser optical heating pulse was generated inside a large room-sized Faraday cage crammed with gear and fired through a hole onto the sample. Despite the complexity of its inner workings, it was designed and maintained to be remarkably easy to use, and thus rapidly developed into a unique facility which attracted cross-disciplinary scientific collaborators from around the world to Josef’s laboratory in Berlin.”

Josef Holzwarth’s early work involved the kinetics and mechanism of the recombination of the ions of water studied with conductivity detection and the association of acridine dyes in water using spectrophotometric and fluorometric detection. Over the years he extended his work to electron- transfer and metal-ligand substitution reactions in micellar solutions, dye binding to DNA and the dynamics of surfactant aggregates and block co-polymers. “A particularly impressive study was the kinetics of the interaction between Gramicidin-A and bilayers of DPPC”, says Paul Fletcher, Emeritus Professor of Physical Chemistry at the University of Hull (UK). For this study, a combination of absorption, fluorescence and turbidity detection was used to interpret the data.

In later years, Holzwarth focused his research on the study of supramolecular dynamics measuring events in real-time, using the mentioned laser temperature jump method together with other kinetic techniques, such as laser flash photolysis, stopped-flow, and continuous flow methods. Arturo López-Quintela, Professor of Physical Chemistry, University of Santiago de Compostela (Spain), remembers Holzwarth as very driven and always keen to directly apply new knowledge into his current research. “For each supramolecular system he developed the required methodology to measure dynamics in real-time, establishing the relationship between dynamics and structure of the supramolecular building blocks, and apply this knowledge to design new supramolecular functions,” says López-Quintela, who will always remember Josef Holzwarth for his kindness and his contagious good humour.

Holzwarth produced relevant contributions in many fields: diffusion-controlled reactions; dynamics of micelles and microemulsions; dynamics and phase transition in vesicles and bilayers; dynamics of block co-polymer self-aggregations; dynamic processes in membrane systems and protein structures; dynamics in gels; interaction of surfactant, dyes, ions and molecules with polymers, biopolymers (including DNA) and macromolecules; and reversible and irreversible enzyme reactions – among others.

Edward M. Eyring, Emeritus Professor of Physical and Analytical Chemistry at the University of Utah (USA) thinks that “Josef Holzwarth was certainly one of the contributors to the field of subnanosecond chemical reactions who was most admired by myself and my late father, Henry Eyring, in the 1970's and 1980's. Josef's sparkling good cheer and creative scientific ideas made him a great favorite speaker at the scientific meetings we attended back in those long ago days.”

Much of Josef Holzwarth’s scientific collaborative work centred around the dynamics of colloidal systems, particularly micelles, microemulsions and block co-polymers. His strong reputation in this area led to his appointment as European Editor of ACS journal Langmuir. Even after his retirement from the Fritz Haber Institute in 2005, this appointment continued until 2008. Cornelia Bohne remembers how serious Josef Holzwarth took his editorial work at Langmuir. “For my first sabbatical in 1998/99, I spent 9 months in Josef’s lab at the FHI”, she says. “Apart from learning much about self-assemblies of block-copolymers, I had many conversations with Josef about the editorial process. These were instrumental to my development as a scientist. Today, in my own role as an editor, I frequently remember his anecdotes about what makes one an effective and good author or reviewer.” MIT Chemical Engineering Professor Alan Hatton has similar fond memories of his short semester stay with Josef, over the summer of ’89, which led to a productive collaboration on the dynamics of reverse micellar systems and block copolymer aggregates in solution.  “Josef was an inspiration in terms of his strong scientific ideals and the joy he gained from probing new dynamic phenomena at time scales previously inaccessible to researchers.  He was generous with his time, and shared not only his wisdom, but also tea from his perpetually-filled, heavily tannin-encrusted flask. Josef was a wonderfully kind colleague and friend.”

Josef Holzwarth has always been active in the scientific community. In addition to his editorial work, he was a talented science manager, always in demand at the FHI. He chaired the FHI library committee for over 25 years, and he organised the renovation of the main building prior to the arrival of Prof. Gerischer in Berlin. He is also remembered as having been an energetic member of the “Fast Reactions in Solution” Discussion Group of the Royal Society of Chemistry. “He attended every meeting of the group over more than 30 years, that’s a record”, says Brian Robinson. “He used to drive all over Europe to attend meetings”, adds Robinson, “and most people who knew him would describe him as an enthusiastic driver as well as a dedicated scientist. He actually trained as a Munich taxi driver in his student days, a job where you not only got the customer to the right destination, you got them there as quickly as possible. I experienced this first hand on a long trip I took with him and my mother in Josef’s Volvo estate car. She appeared to be sleeping as we drove along at speeds higher than 100 mph, but later admitted than she kept her eyes shut the whole time out of pure fear,” Robinson narrates with a laugh. “Josef was kinetically fast in lots of ways.”

His speed and energy are well remembered by all who knew him. He carried out all scientific and non-scientific activities efficiently and rapidly. “Like in his driving, he was usually in a hurry. In particular, Sepp could never resist running upstairs three steps at a time!”, says Alex Bradshaw. He remained that way for as long as he lived, Laurie Peter remembers. “I last saw Sepp at his home in Oberammergau, when we walked together on the local mountain. He was still as full of energy as ever.”

This obituary was a joint effort by all those quoted, and in addition informed by all those who met and worked with him at the FHI. They extend their deepest sympathy to Josef Holzwarth’s wife Ani and all of the family. Especially those outside the FHI want to thank them for their hospitality over the years, memorable trips to conferences, and Ani’s pizza – the best in Europe. Josef Holzwarth was an outstanding and original scientist who will be greatly missed by all his friends in the “fast reactions” community. “The FHI can be proud of his achievements”, concludes Prof. Gerard Meijer, Executive Director at the Fritz Haber Institute.

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