Dr. Prakash T. Aryal on the Quiet Logic of Supramolecular Chemistry
Supramolecular chemistry has reshaped how scientists think about matter. Instead of breaking bonds, it builds complexity through the subtle language of non-covalent interactions — hydrogen bonds, π-stacking, van der Waals forces, hydrophobic effects. The field has produced molecular machines, sensors, and drug delivery prototypes that move beyond the limits of covalent synthesis.
Few Nepali chemists have shaped a corner of this field as visibly as Dr. Prakash T. Aryal. Splitting his career between Kathmandu and research posts abroad, he has built a body of work around mechanically interlocked molecules and responsive host systems, with regular publications on molecular recognition and self-assembly.
Australian readers may have crossed paths with his research without realising it. Aryal has co-authored papers with groups in Melbourne and Canberra, contributed to workshops run by the Royal Australian Chemical Institute's organic division, and spent a formative year on the eastern seaboard. His story is also a story of how supramolecular thinking travels — across institutions, across oceans, and across the time-zone gap that separates Kathmandu from Sydney.
This profile traces the path from a schoolboy in Pokhara to a researcher publishing in journals such as Chemistry – A European Journal and Organic Letters. It also looks at the systems he designs, the students he mentors, and the questions he believes supramolecular chemistry is best placed to answer next.
From the hills of Nepal to the molecular frontier
Aryal grew up in Pokhara, where the chemistry of lake sediments and local medicinal plants first caught his attention. He completed undergraduate studies at Tribhuvan University in Kathmandu, where an elective on organic reaction mechanisms revealed how much he enjoyed designing molecules on paper before reaching for a round-bottom flask.
A scholarship took him to the Indian Institute of Technology Bombay for a Master's degree. There, under the supervision of a moving-rotaxane group, he encountered the literature of Nobel laureate Fraser Stoddart, whose later career included years at the University of New South Wales in Sydney and at Northwestern University. Aryal describes that first encounter with mechanically interlocked molecules as the moment he understood chemistry could be architectural rather than merely synthetic.
What supramolecular chemistry actually builds
To readers outside the field, supramolecular chemistry can sound abstract. In practice, it is the chemistry of parts that fit together — crown ethers that grip potassium ions, cucurbiturils that thread onto viologen guests, calixarenes that fold into molecular baskets. The interactions holding these assemblies together are individually weak, but in concert they produce selective, reversible, and often stimulus-responsive behaviour.
This reversibility distinguishes the discipline from classical synthesis. A supramolecular construct can be made to disassemble on command — by changing pH, adding a competing guest, or applying light. That feature has made these systems useful in sensing, catalysis, separations, and the design of molecular machines that perform mechanical work at the nanoscale.
Aryal's research on rotaxanes and functional macrocycles
Aryal's group at the Centre for Applied Chemistry in Kathmandu works on two kinds of architectures. The first are [2]rotaxanes and [2]catenanes built around urea- and amide-derived macrocycles, where a secondary thread can be ejected and re-inserted by switching solvent conditions. The second are calixarene and pillararene hosts functionalised with fluorescent reporters, used to detect nitroaromatic explosives and anions in water.
His team has also reported switchable organocatalysts in which a macrocyclic wheel blocks or exposes an active site depending on temperature. Beamtime at the Australian Synchrotron in Melbourne, paired with complementary measurements at the Australian Centre for Neutron Scattering, an ANSTO facility south-west of Sydney, has helped resolve disorder in interlocked structures that had resisted crystallisation in Kathmandu.
| System | Driving force | Typical use | Reversibility |
|---|---|---|---|
| Crown ether host-guest | Metal–ion coordination | Selective cation extraction | High |
| Cucurbituril inclusion | Hydrophobic effect, carbonyl portals | Drug solubilisation | High |
| Rotaxane shuttle | π-stacking, hydrogen bonding | Molecular switches | Moderate |
| Calixarene sensor | Hydrogen bonding, π-stacking | Anion or explosive detection | High |
| Metal–organic cage | Coordinative bonds | Guest encapsulation, catalysis | Low to moderate |
Working with Australian laboratories
Aryal's Australian links began during a postdoctoral fellowship at the University of Melbourne, where he joined a group working on anion-binding foldamers. The connection continued through ARC-funded Discovery projects that supported exchanges between Kathmandu and a node at Monash University, and students from both institutions now rotate through shared summer schools.
The geographic split is workable but not trivial. Kathmandu sits around four hours and fifteen minutes behind Sydney, which shapes when joint group meetings can run. Australian diplomatic posts in Kathmandu have also helped Aryal and colleagues navigate researcher visa pathways, including the Temporary Skill Shortage visa that has brought several postdoctoral fellows onto his projects.
Mentorship across two hemispheres
Mentorship is the thread Aryal returns to most often. He supervises a cohort of roughly fifteen graduate students at any given time, with co-supervisors located in Brisbane, Adelaide, and Perth. Online journal clubs, run late at night in Kathmandu to suit a 19:00 AEST slot in Brisbane, have become a quiet institution.
He also runs a winter short course on supramolecular chemistry for final-year undergraduates at Tribhuvan University. The course attracts students who might otherwise have drifted into analytical or pharmaceutical chemistry, and a steady stream of those graduates now travel to Australia each year for PhD programs funded through schemes such as the Research Training Program and the Australia Awards.
Service to the Nepali chemistry community
Beyond the bench, Aryal edits a regional bulletin for the Nepali Chemical Society and coordinates an annual conference bringing together academic chemists from South Asia with diaspora researchers in Sydney and Melbourne. The meetings have introduced several Australian chemists to work coming out of Kathmandu labs.
He is also a familiar voice in outreach at Australian schools, contributing video lectures used by chemistry teachers in regional New South Wales and Victoria. His message to school students is consistent: supramolecular chemistry is a field where small, careful design choices at the molecular scale can change the macroscopic behaviour of materials that touch ordinary life.
Where molecular recognition goes next
Aryal sees three open questions shaping the next decade of his group's work. The first is whether rotaxane-based catalysts can be made cheap enough to compete with conventional organocatalysts in pharmaceutical manufacturing. The second is how macrocyclic hosts can be deployed in cleaner water-treatment systems in regions like the Kathmandu Valley, where traditional methods struggle with industrial effluent. The third is whether molecular machines can move from solution-phase curiosities into solid-state devices that Australian materials chemistry groups are well placed to help characterise.
The applications are practical, even when the molecules themselves are not. That tension — between the elegance of a threaded architecture and the messiness of real-world use — is, for Aryal, the part of the discipline worth spending a career on.
For readers who want to follow his published work as it appears, the simplest concrete next step is to set up an RSS or email alert against Aryal's ORCID profile, which lists every paper with co-authors, funding sources, and links to shared data.