When the 2026 Nobel Prize in Chemistry was announced on 7 October, I immediately thought of a scientist I have known and admired for many years—Dr. Srivari Chandrasekhar, formerly Director of the CSIR–Indian Institute of Chemical Technology, Hyderabad. The Nobel Prize went to Henri B. Kagan and Kenso Soai for their pioneering discoveries concerning how chemical reactions can favour and amplify one of two mirror-image forms of a molecule. Their work addresses one of chemistry’s most intriguing mysteries: why does life favour one of two molecular forms that are mirror images of each other, much like our left and right hands?

In February this year, I wrote an ode titled A Scientist and a Gentleman, describing my personal bond with Dr. Chandrasekhar. I recalled how, during my first visit to his director’s office, he personally fetched a bottle of water from a small refrigerator instead of summoning an assistant. That simple gesture revealed a humility I have always associated with genuinely great scientists. I also wrote about his formidable achievements in organic synthesis, particularly his work on complex natural products and pharmaceutical compounds, as well as his contributions to developing more environmentally sustainable chemical processes.

Dr. Chandrasekhar is a leading Indian exponent of chiral chemistry and asymmetric synthesis. His work includes methods for constructing the precisely arranged molecular fragments required for complex medicines such as eribulin, an anticancer drug. 

I take particular pride in having known a scientist whose work belongs to the same broad field of molecular science that this year’s Nobel Prize has brought into the global spotlight. You don’t need to land on the moon to enjoy the moonlight!

The word chirality comes from the Greek word cheir, meaning hand. To understand it, hold up your two hands with the palms facing you. Now bring them together in a Namaste, and they match perfectly. Yet, if you place one hand directly over the other, with both palms facing the same direction, they cannot be made to coincide exactly. They are mirror images but not identical objects. In the same way, two chiral molecules can have the same atoms and bonds but differ in the three-dimensional arrangement of those atoms. These two forms are called enantiomers. But why should the orientation of a few atoms matter so much? 

The answer lies in the exquisite selectivity of biological systems. Enzymes, receptors, transport proteins and many other biological structures are themselves chiral. A molecule must often fit into them with the precision of a key entering a lock. A right-handed molecular key may fit beautifully; its left-handed counterpart may fit poorly, fail to work, or engage a different biological target.

Thus, the same molecular formula can conceal two very different biological identities.

This is also how chirality can create ‘impurity’. During ordinary chemical synthesis, a reaction may produce equal amounts of both mirror-image molecules, known as a racemic mixture. If only one form provides the desired therapeutic effect, the other may be regarded as an unwanted stereochemical component. Sometimes it is relatively inactive; sometimes it has a different useful effect; and occasionally it introduces serious risks.

The pharmaceutical industry has learned this lesson through costly experience. Modern drug development increasingly depends on determining which molecular form produces the desired effect and whether the other introduces undesirable consequences. Regulatory authorities accordingly require attention to stereochemical identity, purity and biological behaviour.

This year’s Nobel Prize celebrates a deeper achievement of asymmetric synthesis: chemists need not always create both forms and painstakingly separate them afterwards. They can use appropriately designed catalysts and reaction conditions to favour the desired form from the outset. Kagan’s work demonstrated how a small initial imbalance could produce a disproportionately large preference in the final product. Soai explored an even more fascinating possibility: a reaction in which the chiral product helps generate more of its own handed form, amplifying an initially tiny asymmetry.

This brings me to a question. We know that ordinary glucose is predominantly D-glucose, one particular stereochemical form. Its mirror image, L-glucose, has the same molecular formula, C₆H₁₂O₆, and can taste sweet. But the human body’s glucose transport and metabolic systems have evolved mainly to handle D-glucose. Could L-glucose therefore offer sweetness without substantially increasing blood glucose? 

In principle, this is a scientifically interesting possibility. Because ordinary human metabolism does not use L-glucose in the same way as D-glucose, it has attracted interest as a potential low-calorie sweetening compound. But reduced metabolic utilisation does not automatically establish safety. Its intestinal absorption, tolerance, effects on the digestive system, manufacturing cost and long-term consequences would all require careful evaluation. No wonder L-glucose is not an established replacement for ordinary sugar for people managing diabetes.

Edible oils present a more interesting case. Oils are complex mixtures of triglycerides, molecules in which fatty acids are attached to a glycerol backbone. Some triglycerides are chiral, and the position of specific fatty acids on the glycerol backbone can influence digestion, absorption and physical properties. Digestive enzymes do not necessarily treat every molecular arrangement identically. Indeed, research into structured lipids has explored how modifying these arrangements might influence nutritional and technological behaviour. 

But it would be misleading to conclude that simply increasing the proportion of right-handed or left-handed molecules would make any edible oil safer. There is no universal healthy handedness. The health effects of oils depend on many factors, including their fatty-acid composition, degree of processing, oxidation, cooking conditions and quantity consumed. Chirality and stereospecific positioning provide additional possibilities for research, not a simple shortcut to healthier food.

Asymmetric synthesis helps chemists build complex molecules with the precise three-dimensional architecture needed for biological activity. In a potent anticancer compound, an incorrectly oriented group may compromise activity or introduce an unwanted interaction. Creating the desired stereochemistry is therefore not a decorative refinement but part of constructing the intended medicine itself.

Dr. Chandrasekhar’s achievements acquire special significance in this context. His group’s research on synthesising biologically active natural products and pharmaceutical intermediates required exceptional control over molecular structure. His work on the chiral building blocks of eribulin illustrates the painstaking ingenuity involved in translating complex molecular architecture into practical chemistry. 

I have spent much of my professional life observing how advances in one field make transformative applications possible in another. In defence engineering, materials that were originally developed for demanding aerospace applications found new uses in medical devices. In chemistry, the mastery of molecular handedness can similarly move from an abstract scientific problem to the construction of medicines, specialised materials and perhaps future nutritional innovations.

The field also has a philosophical dimension that fascinates me. Living organisms display a remarkable preference for molecular handedness. Proteins are built almost entirely from L-amino acids, while the sugars essential to energy metabolism and the structure of DNA and RNA predominantly belong to the D-series. The letters L and D, derived from the Latin words laevus (left) and dexter (right), distinguish two different three-dimensional arrangements of atoms, like mirror-image forms of the same molecule. This remarkable preference for one molecular form over the other is among the defining chemical characteristics of life.

It is tempting to extend the metaphor to human life. Two individuals may have similar qualifications, opportunities and intelligence, yet their character may lead them in opposite directions. Knowledge can become an instrument of vanity or an expression of service. Authority can demand submission or encourage independence. The outward structures may look similar, but their consequences can be profoundly different.

That was precisely what impressed me about Dr. Chandrasekhar. His intellectual achievements were accompanied by a disposition towards humility and usefulness. In his office, the simple act of offering a visitor water revealed something that no citation index or scientific award could measure.

The Nobel Prize celebrates a magnificent scientific achievement. For me, it also renews my appreciation for the chemists who devote their lives to mastering matter’s hidden architecture. I feel privileged to know Dr. Srivari Chandrasekhar, a scientist whose command of complex molecular synthesis belongs to this remarkable intellectual tradition.

Chirality teaches us that two molecules can be mirror images of one another and yet behave very differently in life. The same is true of human achievement. Scientific brilliance earns admiration, but when joined with humility and compassion, it becomes something greater. That is why, long before this Nobel announcement, I had come to regard Dr. Chandrasekhar as both a scientist and a gentleman. To me, he has always been a Nobel laureate in his own right, with or without the prize.