Prized Science | On faster access to molecules, and quake-resistant buildings
Read about Debabrata Mati's methods leading to valuable molecules and Dipti Ranjan Sahoo's devices and designs to protect buildings hit by earthquakes
Debabrata Maiti, Professor of Chemistry at IIT Mumbai, is one of the recipients of this year’s Shanti Swarup Bhatnagar Prize for Chemical Sciences, sharing it with Akkattu T Biju of IISc Bangalore. Maiti’s work focuses on engineering chemical reactions to yield pharmaceutically and industrially valuable chemicals that would otherwise be difficult to access. In this interview, Maiti explains how his team has developed those reactions by designing tools that modify the structure of various molecules. Read edited excerpts:
Broadly, what is the field of your research?
As synthetic chemists, we aim to make new, harder-to-access chemicals from easily available starting materials. Typically, this is accomplished through the use of cost-efficient and multistep processes. Our goal is to shorten this pathway to a single-step process. Our work has been applying the concept of “valorisation", which is critical to constructing pharmacologically and industrially valuable chemicals from seemingly insignificant molecules.
We take inspiration from nature and employ various tools like engineered metal-ligand complexes [these are complexes in which a molecule or ion is attached to a metal by chemical bonding] and enzymes that are often inaccessible in conventional chemistry for selective molecular framework modification.
What is that exactly?
Organic molecules typically contain lots of carbon-hydrogen (C–H) bonds. Making new molecules would be much simpler and cheaper if you could somehow edit the C– H bonds into new chemical bonds.
We have developed reactions that are driven by catalysis, a process in which the reaction is influenced by substances which themselves remain unchanged at the end of the reaction. Catalysis changes the course of a reaction and makes it easier to access under much simpler and milder conditions.
In one of our recent works, our team developed a counter-intuitive chemical reaction to simplify the production of biologically important compounds. The reaction activates unreactive C–H bonds to form essential compounds called lactones, which are found in natural products and pharmaceuticals.
Editing the C–H bonds is not easy. We don't want to activate all the C–H bonds of the molecules at the same time; that would not be of any practical use. There is also the question of selectivity, when multiple similar C–H bonds are present in the molecule, and you only need to activate one. To achieve selectivity, our group has mainly focused on discovering new organometallic catalysts and the design of ligands.
What are the implications of such research?
C–H activation has just started to show the promise of delivering a sustainable and economical chemical transformation. The processes we have created simplify the manufacturing of life-saving medications, agrochemicals, and critical commodities.
Our team at IIT Bombay is working on catalyst design for transforming organic molecules to prepare natural products, drug molecules and materials in step and atom-economic fashion. These conceptual developments have significantly impacted materials research, agrochemicals and pharmaceuticals industry.
We have been closely working with research-focused companies aiming at new drug discovery, agrochemicals and materials. Based on our recent discovery, a chemical called Maiti-Bera-Modak Auxiliary” is now commercially available from Sigma-Aldrich while “Maiti-Bag Auxiliary” from Tokyo Chemical Industry.
A seismic shift in building resilience
What goes into the research of making a building resistant to earthquakes?
My group has been working on three aspects of seismic-resilient infrastructure. One aspect is the development of energy-absorbing devices. We have developed three different types of these devices (called structural fuses) using locally available materials. The goal is to make them easily available and affordable.
The other aspects of our work are the use of novel materials for seismic-resilient infrastructure, and new seismic design methods. We have also proposed a performance-based plastic design method, which provides designers with the flexibility to design a new structure for a targeted seismic intensity level in a simplified way. It also allows them to make a decision on the cost and time required to upgrade existing seismically deficient structures.
How do structural fuses work?
These are energy-absorbing devices, which are developed in order to overcome a problem associated with metallic substances, such as steel and aluminium, which tend to buckle under compression loading, thereby making them ineffective in resisting seismic loads. Structural fuses seek to restrain such buckling and maximise the energy-absorbing capacity. Depending on the site constraints, these devices may be installed diagonally between joints of members, or partially filling the panel or just below the beams of buildings.
For each one of the three types of structural fuses we have developed, we have carried out prototype testing and application on building frames to study their effectiveness under earthquake loading. These devices are not only very effective and inexpensive, but also ready for on-site production and installation. In some of these devices, novel smart materials available in India have been adopted.
How do you develop such materials?
One of the objectives of seismic-resilient structures is to make them usable during and after an earthquake event. Very often, structures exhibit deformation after an earthquake, leaving them in a tilted position due to some damage. Although this damage may not be severe as far as safety is concerned, no one would occupy a tilted structure. To bring them back to their original position, we have developed self-centring structural systems using smart materials that have sufficient strength, deformability and re-centring characteristics. We have tested these materials in the laboratory for mechanical characteristics and quantifying their earthquake-resistant properties.
What makes your seismic design methods novel?
Currently, the earthquake-resistant design method being followed is primarily based on the lateral force a building would be exposed to. This method assumes that a force-based approach should provide adequate safety against structural collapse by ensuring prescribed detailing. Many past earthquakes have shown, however, that such a design method may not be adequate to provide safety and serviceability for important structures, such as hospitals.
On the other hand, a performance-based design method, which my research group works on, provides complete information on the weakest elements that require more attention, the level of safety for a particular intensity of an earthquake, and the maximum earthquake impact that the structure can survive during the design stage.
Other areas of our research include cold-formed steel structures, column-free steel structures, composite hybrid columns, high-strength steel and advanced seismic testing methods. To date, we have filed six patents on passive vibration control devices.
The Shanti Swarup Bhatnagar Prizes for Science and Technology were awarded to 12 researchers in seven disciplines. The annual prizes, given by the Council of Scientific and Industrial Research, recognise scientists under the age of 45 for notable or outstanding research. Read interviews of all 12 awardees in the Prized Science series