Nanotechnology at Northwestern

Meet Yunyan Qiu, a postdoctoral fellow in the Stoddart Group

By Mark Heiden

October 29, 2020

Yunyan Qiu is a postdoctoral fellow in the Stoddart Group, which harnesses molecular recognition and self-assembly processes in template-directed protocols for the synthesis of functionalized and mechanized molecules, prior to their being introduced into integrated nanosystems.

Where are you originally from?

I grew up in a small town in Jilin Province in the northeastern part of China.

Where did you complete your undergraduate degree?

I completed my undergraduate degree, majoring in pharmaceutical science, at Peking University in China. Then I came to the U.S. and earned my PhD in Chemistry at Carnegie Mellon University under the guidance of Professors Kevin Noonan and Tomek Kowalewski. My graduate research encompassed organometallic chemistry and polymer science with a focus on the rational design of conjugated polymers, as well as developing controlled methodologies to afford well-defined functional materials using metal-catalyzed cross-coupling reactions.

When did you first become interested in chemistry and biochemistry?

I became interested in chemistry in middle school since I was quite good at it at the time. This interest grew in high school, and then I had the opportunity to learn more about it at Peking University and practice medicinal chemistry in Prof. Demin Zhou’s lab, working on chemical modifications of pre-drugs to increase their efficacy.

How do you explain what you study to non-scientists?

My primary research focus in the Stoddart Group is to design and harness artificial molecular machines (AMMs) to produce functional polymers and materials in a controlled manner. Nature has practiced this ability for a very long time as it utilizes enzymatic biomolecular machines, such as DNA polymerases and ribosomes, to produce functional biomacromolecules including DNA and proteins with precise lengths and specific monomer sequences.

Similarly, synthetic chemists have begun to realize molecular synthesis and functionalization by employing wholly synthetic artificial molecular machines based on mechanically interlocked molecules such as rotaxanes (where rings are mechanically interlocked onto dumbbells) and catenanes (where rings are mechanically interlocked with each other). The application of AMMs in the controlled synthesis and modification of functional molecules and materials, however, has not yet reached its full potential, especially in terms of the precision synthesis of polymers and biopolymers.

As a polymer chemist by training, I have developed an ever-increasing amount of interest in exploring practical applications of artificial molecular pumps (AMPs), a subset of AMMs, in polymer chemistry and materials science. In particular, I have worked on harnessing AMPs as precise polyrotaxane synthesizers to produce enthalpically and entropically demanding mechanically interlocked polymers in a controlled manner.

You have recently published several papers on pumps, including the most precise method ever developed for building polyrotaxanes. What attracted you to this subject, and what do you hope to achieve with your research?

As I mentioned previously, I have become fascinated with exploring artificial molecular pumps/machines in the context of polymer chemistry and materials science, considering the background of my graduate study. The excitement of being able to combine what I have learned during my PhD and what I am about to learn here at NU is the primary reason behind my research interest in this subject.

When I joined Fraser’s group, my intuition told me that there would be an enormous amount of opportunities emerging from the marriage of AMMs and polymer chemistry. And indeed, over the past two years, I have been able to investigate in great detail how to utilize artificial molecular pumps to produce polyrotaxanes with deft control over the number of threaded rings. The ability to precisely control the number of threaded rings installed onto any size-fit polymer chains, regardless of non-covalent bonding interactions between the rings and polymer backbones, opens many possibilities to fine-tune the mechanical properties of the resultant slide-ring polymer networks.

Another exciting research direction I am currently working on is to apply AMPs in the production of sequence-controlled polyrotaxanes by means of controlling the specific order of threaded rings. In the near future, I hope these research efforts will pave the way to our having complete control over monomer sequences in synthetic polymers and eventually realize this holy grail of precision polymer synthesis.

What has been a highlight of your time at Northwestern?

From a scientific perspective, I am glad that I am able to present the most recent progress from the Stoddart lab in terms of research on artificial molecular pumps to the whole community. From a personal perspective, I am grateful to learn from the best through everyday interactions with the Stoddart group members, including many talented graduate students and postdocs.

What has been the most challenging aspect of your work or your time at Northwestern?

Being a polymer chemist by training represents both an opportunity and a great challenge to me since I had no prior experiences in supramolecular chemistry and artificial molecular machines. Thankfully, I am a synthetic chemist who enjoys making new molecules very much and has become quite good at it over time. By learning from many talented students and postdocs from Stoddart’s group, I have made myself comfortable with these exciting new research areas.

Can you tell me about your experiences either being mentored or mentoring others?

Over my academic training from undergraduate to graduate, and eventually to my postdoc here at NU, I have been grateful to many of my mentors and supervisors. I started my graduate study at CMU the same year that my PhD advisor Prof Kevin Noonan started his assistant professorship there. I learned a lot from Kevin, not only on how to conduct research but also how to run a newly established research laboratory. These experiences were extremely valuable for me to start my own independent academic career in the U.S.

I have also benefited tremendously from Sir Fraser because he is and will always be giving his full support to young researchers by offering us 100% freedom to explore our own research interests. The opportunity to serve as my own supervisor, design/conduct my own experiments, and write manuscripts from my own perspective is what I need the most to grow into an independent principal investigator in the future.

I was also fortunate to mentor many undergraduate and graduate students during my time at CMU and NU. I guess the biggest moment of joy for me is to be told that they will be admitted to their dream graduate schools, start their dream jobs, or simply follow their hearts to pursue happiness in their lives.

What are your hobbies outside of the lab?

I think it has been a good and useful practice to separate personal life from work. That means I try to devote 100% of my attention at work when I am in the lab and try not to worry about work at all when I am at home. The year 2020, however, has been challenging for me to do this. Outside of the lab, I enjoy watching sci-fi movies and exploring U.S. national parks with my family.