Chemistry for the Future: A Youth Researcher Lecture on Supramolecular Chemistry
Words by: Jachelle G. Linantud
Once a hopeful and hardworking BS Chemistry student, Asst. Prof. Justine M. Kalaw returned to the University and delivered his talk on “Supramolecular Chemistry of Cyclodextrins and their Derivatives” on March 29, at the Central Laboratory. The annual departmental lecture was hosted by the Department of Chemistry where freshman, sophomore, and senior students of the department participated.
The program started on a light note with Prof. Bernard John V. Tongol, Ph.D. as the moderator recalling the days when Dr. Kalaw was still a student of his, before officially starting the program with the program flow and an opening prayer from Assoc. Prof. Cecilia M. Villaraza, M.Sc. The Asst. Dean of the College of Science, Prof. Ma. Claudette S. Agnes, Ph.D., gave her opening remarks where she highlighted the importance of chemistry in sustainable development. She also addressed the undergraduate students present to relax and listen well during the lecture as this can be a topic in their future research.
Another member of the Department, Acd. Prof. Fortunato B. Sevilla III, Ph.D., reminisced on the days when he was the thesis adviser of Dr. Kalaw during his Bachelor’s and Master’s Degrees, and joked that the older faculty members had to introduce the new and younger faculty members. He mentioned how a DOST scholarship is helpful to those who want to pursue graduate school and that researches made in the Philippines by Filipino scientists can also be published in good research journals. He also mentioned that the road Dr. Kalaw had to take was not an easy one, as he had to repeat his Master’s Degree to transition from Analytical Chemistry to Organic Chemistry when he went to Japan after being part of the teaching staff of the department. However because of this, Dr. Kalaw was able to use Organic Chemistry in Analytical Chemistry, and earned an award from the Society of Cyclodextrin in Japan.
After the introductions, it was Dr. Kalaw’s turn to take the stage of the auditorium. Since Supramolecular Chemistry is not a widely taught subject to undergraduate Chemistry majors, he gave a comprehensive summary on what it is all about. He started with its definition as the “chemistry beyond the molecule” and the “study of various noncovalent interactions”. He also highlighted the difference between Molecular and Supramolecular Chemistry as the former is more of the actual topic of Chemistry, rather than the latter. A timeline of the history of Supramolecular Chemistry and how scientists made further discoveries in recent years was also shared.
The summary on Supramolecular Chemistry was followed by an introduction of Cyclodextrins or CDs, the main part of the day’s lecture. The 1st and 2nd years were only vaguely familiar with the compound as they are still taking Organic Chemistry, while the. 4th years have an idea about it as they already have lessons in Advance Organic Chemistry. Nonetheless, all students were engaged in the lecture. Dr. Kalaw outlined different topics of Cyclodextrins, such as its torus structure, host-guest chemistry, supramolecular assemblies, recent applications, limitations, and modifications.
He also shared some findings from his postgraduate research in a university in Japan, which he divided into two parts. The first part encompassed the “Inclusion Complex Formation in Nonpolar Solvents” where the crystal structure of TIPS-β-CD-Pyrene Inclusion Complex was shown and that benzene molecules stabilize the inclusion complex. The synthesis of 2-O-Modified TBDMS-β-CD was also highlighted where a substitution reaction using pyridine as the base molecule yields 83%. This substitution reaction was a straightforward synthetic reaction with purification done through silica gel chromatography, and analysis through H NMR. An increase in fluorescence in the fluorescence titration of pyrene means that the guest molecule pyrene and host molecule are actually reacting with each other. Dr. Kalaw also presented a proposed structure for this inclusion complex of pyrene in cyclohexane. As a summary to the first part, it was stated that there was strong binding to aromatic guests from the aromatic substitutions at the 2-O-position of TBDMS-β-CD even though there were presence of nonpolar solvent molecules. There was also a high chiral selectivity that was shown by the hosts for 1-(1-naphthyl)ethylamine in cyclohexane.
The second part of the lecture focused on the preparation of highly regulated supramolecular assembly of 2-O-methylated-α-CD where different types of channels were introduced, and Dr. Kalaw highlighted that different assembly modes mean different types of morphology. The regulation of α-CD channel assemblies by methylation was also outlined. From the preparation of supramolecular structures of 2-Me-α-CD, he highlighted that inclusion complex dictates the structure being formed, and assembly mode is not affected by type of poor solvent used. From his studies, Dr. Kalaw shared that the X-ray crystal structures of 2-Me-α-CD inclusion complexes takes a lot of time and trial and error process, and that it took him a month to get a crystal structure. To sum up the second part, epitaxial growth on the highly oriented pyrolytic graphite (HOPG) substrate was used to fabricate the microstructures of 2-Me-α-CD/benzene inclusion complex. The facile structure morphology transition of 6-Me-β-CD was realized in methanol and cyclohexane or hexane.
For the last part of the lecture, Dr. Kalaw shared his experiences in Osaka University, where he spent five years for his postgraduate studies. He mentioned that there were three campuses and a specific laboratory for Supramolecular Chemistry wherein the name is derived from the current head professor teaching. He also shared his difficulties as the only international student and how he was sometimes left out during group meetings as his fellow scientists were speaking in Japanese. However, he still encouraged the undergraduate students, especially the 4th years in applying to graduate school in Japan through various fully-funded scholarships for international students.
Towards the end of the Departmental Lecture, an open forum was held where students and members of the faculty went up to the microphone to further discuss some topics they found interesting. Presentation of Certificate of Appreciation with Asst. Dean Prof. Agnes and Dept. Chair Assoc. Prof. Salcedo soon followed. For the closing remarks, Assoc. Prof. Salcedo extended his gratitude to the speaker, saying that “The journey of Dr. Kalaw is an inspiration and. the path to success is not always straightforward. It takes hard work and persistence to take risks.” He referred to the Chemistry Alternative Lecture done last March 28 by his colleague that pressure will create diamonds, as a reminder to the students in attendance. He also addressed this year’s Departmental Lecture as a “Young Researcher Lecture in Chemistry” as this is the Department of Chemistry sending a message that they recognize the value of the student researchers’ contribution and to provide a platform to share ideas. The lecture also increased the visibility of the Department of Chemistry by promoting the work of young researchers and contributing to long-term sustainability and advancement of the field. Lastly, he emphasized the importance of supporting and investing in the future of Chemistry and Science in the Philippines.
