The Portrait of a Scientist: Prof. Dr. Yusuf Yağcı

We had lost our faculty member Prof. Dr. Yusuf Yağcı, known for his academic studies and great contributions to the scientific world, on January 30. 2023. We asked his students and colleagues about our esteemed professor, who stood out with his friendly personality…

Istanbul Technical University (ITU) commemorated Prof. Dr. Yusuf Yağcı with a ceremony on the first anniversary of his passing away. Throughout his career, Yusuf Yağcı contributed to the academic development of hundreds of students, including PhD students, and played an important role in the development of chemistry in Türkiye.

In order to enable new students and young scientists newly joining ITU to get to know the inspiring legacy of Prof. Dr. Yağcı, whom we commemorate with respect on his 72^nd birthday, five academics from among his students and colleagues answered the questions of ITU Communication Directorate, Media and Communication Office.

Interview: Cüneyt Altındaş, News Editor: Fatih Çünkioğlu

“There was no difference between conducting scientific studies and spending time on his hobbies”

— What do you think was Prof. Dr. Yusuf Yağcı’s main source of motivation while pursuing his studies?

Prof. Dr. Nergis Arsu: First of all, behind Yusuf Hoca’s motivation in his academic and scientific studies was his wife (Emine Yağcı), who understood his enthusiasm perfectly and supported him all the time. In addition, I think undertaking new research topics and studies was his biggest motivation. He had a distinctively fast working pace and was an incredible scientist who thought about the title while still planning many of his studies. After each study, he would say “Next please!” and continue working.

Prof. Dr. Barış Kışkan: Like every academic, Yusuf Hoca was motivated by the desire to contribute to the academia and achieve success with his work. For this reason, he would never miss important congresses to show and introduce his work. He liked establishing close relationships with people after making presentations at congresses. Being able to meet academically outstanding people and being a part of that club was a great source of motivation for Yusuf Hoca.

Assoc. Prof. Dr. Muhammet Ü. Kahveci: Our esteemed professor Yusuf Hoca was a person who loved his country and nation very much. Whatever the circumstances, he strived to add value to his country and nation. Moreover, he loved his work, I mean polymer science and chemistry. Even during the pandemic days, he would come to his office to work even though his home was far away. He enjoyed his work immensely and therefore never lost his enthusiasm. He always instilled this enthusiasm in us, his students. He also liked to reflect the structures/phenomena he saw in nature in his work, that is, biomimetic studies. For example, in a study published in the Nature Communications journal, he developed a polymerization system inspired by the behavior of the dandelion.¹

Assoc. Prof. Dr. Ali Görkem Yılmaz: His biggest source of motivation was to do his job in the best and most proper way. In addition to being the best in his field, Yusuf Hoca was also working very hard to reveal his full potential.

Res. Asst. Dr. Hüseyin Cem Kılıçlar: For Yusuf Hoca, there was no difference between conducting scientific studies and spending time on his hobbies. He was incredibly happy when he saw that the work he had been thinking about and focusing on was realized. Partly for this reason, whenever he had a new idea, he would come to the laboratory with great excitement and tell us about his new idea. Afterwards, he would amuse us by telling with a smile how he came up with the idea. If an idea that excited Yusuf Hoca came to him in the evening, he couldn’t wait for the morning, but would send an e-mail or call you. I think that the happiness he experienced due to the positive results and comments he received later on enabled him to work tirelessly and to be among the best in the world in his field for a long time.

“He is the teacher of many professors in the field of polymer chemistry”

— To what extent did Yusuf Hoca’s work contribute to the academia and what do you think is his role in and impact on the chemistry studies in our country?

Prof. Dr. Nergis Arsu: He carried out very important studies on cationic and free radical photopolymerization that pioneered the realization of click chemistry at room temperature through stimulation with light, which has become increasingly important in the last 20 years. Yusuf Hoca, who developed controlled polymerization methods, has also done very successful work especially on benzoxazine-based high-performance thermosetting polymers.

His nearly 800 publications so far attest to his contribution to the scientific world. As a matter of fact, his establishing bilateral collaborations and meticulously following the studies and bringing them to conclusion has been a benefit for both parties. His most important contribution to our country and the academia is sharing his scientific understanding and approach with his students and researchers.

Prof. Dr. Barış Kışkan: Yusuf Yağcı’s main field of study was photopolymerization. In addition, he was generally interested in polymer synthesis and various related chemical methods. His area of interest was synthesizing functional polymers using different methods. Yusuf Hoca’s greatest contribution to the scientific literature is in the field of photopolymerization and photochemistry. This is also the topic of his doctoral thesis in which he was interested throughout his life. Indeed, his major contribution in this field is the application of photochemistry to controlled polymer synthesis and synthesis of complex polymers called “macromolecular architecture.”

Yusuf Hoca’s greatest contribution to the field of chemistry in our country was his efforts to establish polymer chemistry in Türkiye and to raise qualified academics in this field. Yusuf Hoca had many students who became professors and associate professors after graduating and helped the development of polymer chemistry in our country.

Assoc. Prof. Dr. Muhammet Ü. Kahveci: Prof. Dr. Yusuf Yağcı did studies in the field of polymer science and chemistry on polymer synthesis, controlled/living polymerizations, polymer modification, click reactions, functional polymers, and the use of light in polymer chemistry. In particular, he did groundbreaking studies on photopolymerization and light-induced (photochemical) reactions. He is the recipient of dozens of national and international awards. He is highly respected in the international polymer community. Whomever you ask in the polymer community around the world, his name is mentioned with respect. This respectability is an indication of the high level of his contribution to the field. In our country, he is the teacher of many professors in the field of polymer chemistry. Therefore, he is one of the most important scientists of our country in this field.

Assoc. Prof. Dr. Ali Görkem Yılmaz: Yusuf Hoca is one of the world’s leading chemists, especially in light-induced polymerization. Even when we look at the studies carried out abroad today, he is one of the few names that come to mind when photopolymerization is mentioned. As can be seen from the number of academics he raised and those he sent to the industry, he had a great impact on the field. In addition, because of his being a very strong communicator, he was a person who influenced young people, became a role model, and therefore increased interest in the field.

Res. Asst. Dr. Hüseyin Cem Kılıçlar: Yusuf Hoca is among the top ten polymer chemistry researchers all over the world. His contribution to and impact on the field was way higher than the amazing statistics yielded by these measurement techniques. At the congresses we attended with Yusuf Hoca, I personally witnessed the respect that the leading names in the field such as Kris Matyjaszewski, Axel Müller, Cyriller Boyer, Jacques Lalevee, Nikos Hadjichristidis and many other professors felt for Yusuf Hoca and their curiosity for his views on novel topics.

It is incredibly difficult to overcome all kinds of challenges over the years, to be respected so much by world-renowned and leading names in the field, and to achieve all of this by staying in our country. As a matter of fact, some of the names I mentioned above are people who left their countries to pursue their research careers in other countries. Yusuf Hoca’s patriotism and all his achievements continue to guide and lead the way for us, his students.

“Like the famous painter Rembrandt’s use of light”

— Which of his works did he cherish the most, said “I am glad to have done it” and he was most happy with the results?

Prof. Dr. Nergis Arsu: As you can imagine, having made nearly 800 publications, Yusuf Yağcı never stopped and continued his studies. I think the most important reason why he neglected his health and rushed to his office even after a doctor’s examination was the enthusiasm he felt to finish a publication or wondering the results of the studies by his students. Yusuf Hoca clearly remembered the content and year of every publication he made, and I think he was motivated to do better every time he turned a new discovery into a publication.

Prof. Dr. Barış Kışkan: Among the studies that Yusuf Hoca liked the most and was most happy with the results were photochemically controlled polymerization systems and studies on click chemistry triggered by parallel photochemical methods. The main reason for this was that especially his articles on these topics are shown among the pioneering studies in the world in this field.

Assoc. Prof. Dr. Muhammet Ü. Kahveci: Prof. Dr. Yusuf Yağcı gave importance to all his works. But I can share a few studies that I personally witnessed and he was very excited about. He felt great excitement about some of his studies on light-induced polymerization (photopolymerization). His eyes would shine with a childlike excitement when he was talking about his article published in JACS, the most important journal in the field of chemistry.

In one of our conversations, we were talking about his photochemical studies. He would talk about these studies with great excitement and as if talking about a work of art, by referring to the famous painter Rembrandt’s use of light. On the other hand, he would occasionally reproach me sweetly about a study that he said he was glad he had done and that received many citations. The work was frequently cited, and he couldn’t help saying “It would have been good if we had continued.” This study he handed over to me is about the prevention of oxygen inhibition, a major problem of radical polymerizations by means of sugar and an enzyme. This study, which was first submitted to the Science journal but was rejected and published in another journal, did not attract much attention at the time. Yusuf Hoca expected me to expand the study, but it remained as a single article since it coincided with the completion of my PhD. However, in the following period, when the importance of this study was understood, many articles were published on it and it received many citations. Because of this, Yusuf Hoca would reproach me sweetly or, in his words, he would give me a “roasting.”

Assoc. Prof. Dr. Ali Görkem Yılmaz: First of all, he loved what he was doing. As a matter of fact, every article, from his first publication to his last, excited him. He would also list them all and look back.

Res. Asst. Dr. Hüseyin Cem Kılıçlar: I would like to answer this with an answer he personally gave. He always said, “I am glad that I married Emine Hanım.” He always told how Emine Hanım made his life easier, how she helped him focus on science.

“He wanted the Turkish equivalents of new chemistry terms to be used”

— Are there any unfinished studies that he wanted to continue, and do you continue these studies?

Prof. Dr. Nergis Arsu: Certainly there was, because he had a research group with many students. There were studies we were focusing on together and even new studies we were going to talk about. Unfortunately, it didn’t happen. But the many students he raised, some of whom are academics and some of whom work in the industry, will carry the “Yağcı School” into the future.

Prof. Dr. Barış Kışkan: There are some works of Yusuf Hoca that are left unfinished due to his passing away. In particular, there are some unfinished studies on the application of manganese chemistry to photopolymerization. We completed and published some of these studies, and we continue to work on some of them in our laboratory.

Assoc. Prof. Dr. Muhammet Ü. Kahveci: In our recent conversations with Yusuf Hoca, he would talk excitedly about the projects, plans and studies he was currently thinking about. So, he had many unfinished studies. There is a review article that we worked on together and that I am currently continuing. The studies and projects of his doctoral students continue as well. Yusuf Hoca also wanted the Turkish equivalents of new chemistry terms to be used. The term he mentioned the most was “çıt çıt” chemistry, which is the Turkish equivalent of “click” chemistry.

Assoc. Prof. Dr. Ali Görkem Yılmaz: We had a study on which we were working together. We completed it last year.

Res. Asst. Dr. Hüseyin Cem Kılıçlar: Yusuf Hoca had nearly ten ongoing and unfinished studies that I know of. Some of these were published by us after his passing away. He also had plans for after the unfinished studies. He envisioned the continuation of active research after its completion. These studies are being continued in our laboratory within the framework of his vision.

“He was like a father to some of us, like an elder brother to others”

— What kind of person was Prof. Dr. Yusuf Yağcı through the eyes of his colleagues and students?

Prof. Dr. Nergis Arsu: Yusuf Hoca was a very hardworking, humorous academic who followed his work very well, and his criticisms in joint studies made the work more valuable. Moreover, as a young researcher, you always felt the confidence of leaning your back on a strong scientist.

Prof. Dr. Barış Kışkan: Yusuf Hoca will be remembered in the department and among his colleagues mostly for his diligence, dedication to his job, practicalness, sociability, liking to give advice and criticize, giving credit to those who deserve it and paying attention to this issue.

Assoc. Prof. Dr. Muhammet Ü. Kahveci: Whoever is asked about Yusuf Hoca, they will tell you about his identity as a jocular, cheerful, and equally good and qualified scientist.

Assoc. Prof. Dr. Ali Görkem Yılmaz: To answer this question as someone who was his student, he was a difficult person in the student’s perception. With my current mindset, I see that he is actually not a difficult person at all. He was someone who always pushed you for success and increased your productivity.

Res. Asst. Dr. Hüseyin Cem Kılıçlar: He had a very special place. This is not something that can be explained and only those who know him can understand. He was a father to some and an elder brother to others. However, the truth is that his place was different and very big for everyone.

“Like light that is the key to his work, he became a light for the future”

— In your opinion, how and in what way will Yusuf Yağcı Hoca be remembered the most?

Prof. Dr. Nergis Arsu: I have known Yusuf Hoca for about 30 years. He was a scientist who would be a role model for young people interested in scientific studies and his door was open to anyone who wanted to work with him. He was an extraordinary scientist who worked with incredible joy and reflected this joy to others. In fact, he explained this very well in his article “The Joy of Science” he wrote for a magazine years ago. As the saying goes, “scientists are boring”; this was not true for him. On the contrary, he enjoyed life as much as he enjoyed science. Yusuf Hoca was not an ordinary scientist. The biggest reason or his purpose of humbly sharing his achievements was to bring the distance to science closer and make it enviable. With the poems he recited at congresses, the dance activities, and the songs he sang, he actually reflected the aspects of life that a hardworking scientist enjoyed. And he was very successful in that, too. Like light that is the key to his work, he became a light for the future.

Prof. Dr. Barış Kışkan: Yusuf Hoca will surely be remembered for his academic achievements. Although this is clear, those who know him will remember him for his strong social aspect and, relatedly, fondness for soccer. For Yusuf Hoca, playing soccer was the reflection of his social side rather than a sports activity.

Assoc. Prof. Dr. Muhammet Ü. Kahveci: He would kid with everyone, whether they were a student, professor, administrative staff, dean or even rector, make jokes and establish a very good dialog with people in this way. He loved people so much that he would kid even with people he didn’t know. Our esteemed Yusuf Hoca will be remembered as a pioneering scientist, a wonderful supervisor, a cheerful and jocular friend, an ambitious soccer player and an excellent husband. I will always keep him in my heart with his cheerful voice that is always in my ears and his cherished memory. I once again wish God’s mercy to my Yusuf Hoca.

Assoc. Prof. Dr. Ali Görkem Yılmaz: I will remember him mostly for his fun, motivating and humorous sides.

Res. Asst. Dr. Hüseyin Cem Kılıçlar: I will remember him with songs: “Strangers in the Night”, “Twist”, “Elveda Meyhaneci”... By the way, he is never out of my mind. Every morning as I enter the organic floor, I look at the windows above his room to see if the lights are on; when people are getting off his service bus, I look at people to see if he is getting off too; every time I return from the cafeteria, I look at the window of his room to see if it is open; I will not sit idly at the office, worrying if he will come and give us his sweet roasting; when I go to the service bus in the evening, I look left and right to see if we will meet each other there … These habits haven’t gone away for a year, and I don’t think they will. He would come to us and say that he was here, he was working, and we should work too. He can now say these without coming.

About the interviewees

Prof. Dr. Nergis Arsu (Yıldız Technical University): She started her scientific studies with Yusuf Yağcı after her PhD and continued until Prof. Dr. Yağcı’s passing away. Arsu and Yağcı families were seeing each other closely.

Prof. Dr. Barış Kışkan (Istanbul Technical University): He completed his master’s and PhD under Yusuf Yağcı’s supervision. Having worked with Yağcı for over 17 years, Prof. Dr. Kışkan continued to work in Yağcı’s laboratory for some time after receiving the title of professor as well.

Assoc. Prof. Dr. Muhammet Ü. Kahveci (Istanbul Technical University): He conducted his master’s and PhD studies with Prof. Dr. Yağcı. He was among the people who were very close to Yağcı socially.

Assoc. Prof. Dr. Ali Görkem Yılmaz: He continued his academic studies with Prof. Dr. Yusuf Yağcı for 17 years, starting from the time of his undergraduate graduation research.

Res. Asst. Dr. Hüseyin Cem Kılıçlar (Istanbul Technical University): He did his PhD with Yusuf Yağcı. He was among the students Prof. Dr. Yağcı trusted and appreciated the most and closest to him in the last two years of his life. 

¹ (Li, Z.; Zou, X.; Shi, F.; Liu, R.; Yagci, Y., Highly efficient dandelion-like near-infrared light photoinitiator for free radical and thiol-ene photopolymerizations. Nature Communications 2019, 10 (1), 3560.)