With deep concern we have learned that our colleague, mentor and teacher Prof. Maximilian Knollmüller died on 25.4.2021 after a long illness that was endured with great patience in the 87^th year of life.

Maximilian Knollmüller was born in 1935 in Linz. After the final exam with distinction in the Realgymnasium in Schlierbach he began to study in 1954 chemistry as major and physics as minor subject at the University of Vienna. He completed the study in 1962 with a dissertation under the guidance of Prof. Otto Hromatka on "Syntheses in the Phenthiazin Series". Already at this time he worked as a scientific assistant at the Institute of Physical Chemistry of the University of Vienna.

With the appointment of his mentor and teacher Otto Hromatka to the Technische Hochschule Wien in 1963 he also moved to our university. First as a university assistant and since 1970 as a senior assistant employed, he submitted his habilitation thesis on "Cyclic and Bicyclic Sulfamides" in 1971 and received the venia docendi for the subject "Organic Chemistry" in 1972.

The scientific interests of Max Knollmüller were at that time in the field of heterocycles, whereby he had not only their synthesis and properties in mind, but very early theoretical problems in this context were in his focus. His theoretical considerations on reaction mechanisms and stereochemical issues he underpinned with physical chemical measurement methods. It was therefore not surprising that in 1968 he became head of his own research group. In February 1974 he was then appointed as associate professor and became head of the newly established Department of Physical Organic Chemistry at the Institute of Organic Chemistry. In the following years Max Knollmüller expanded his scientific ouevre with contributions to the photochemical synthesis of organic compounds. Also regarding this topic he was particularly interested in the physical chemical aspects.

In addition to his scientific work, Max Knollmüller was also a committed university teacher. His enthusiastic lectures on physical organic chemistry were highly appreciated by the students and it succeeded in many of his listeners to ignite that fire of curiosity that is essential for a scientific career.

Last not least Max Knollmüller was also involved very intensively in university self-government. Particularly noteworthy is his role as head of the Institute for Organic Chemistry in the period from 01.10.1985 to 30.09.1993. It was a very exciting time for the institute, because at that time the planning for today's "Loschmidt Trakt" (building BI at Getreidemarkt) was in progress. The large underground students´ laboratory in the area of BK, which is nowadays indispensable for a regular teaching process, was originally not foreseen in the planning. Due to the vehement negotiation of Prof. Knollmüller, it was still included in the planning and finally built.

At the end of the year 1999/2000, the active service of Prof. Maximilian Knollmüller ended. He remained connected to the institute, continued to be very interested in scientific issues and acted as advisor in various projects. He would certainly have practiced these activities to the old age. Unfortunately, that was not awarded to him because of his progressive illness.

Max Knollmüller was modest, smart and dutiful. At the same time he was always friendly and helpful. His principles he remained faithful to his life. So he became a model for many. In all the years at TU Wien, his personal commitment was an important and reliable contribution to the positive development of the house.

We will retain him in a living memory.

Christian Noe, Peter Gärtner, Hannes Fröhlich, Marko Mihovilovic