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Department of Inorganic and Physical Chemistry

  • Spectroscopy as a tool

Atoms are the basic unit of study to chemists, and different kinds of spectroscopy one of the most important tools. Most of what we know about the structure of atoms and molecules comes from studying their interaction with light (electromagnetic radiation). By dissecting the light from a particular object, chemists can infer different properties of the object. Each element has a characteristic spectrum (pictured on the right).

Credits: Structure of Atom modified from HowStuffWorks. Spectra from N G Douglas, Leiden University.

The Department in a sense straddles two sides of the same coin. Inorganic chemistry deals with synthesis and properties of inorganic compounds, which are mostly metal complexes, organic-inorganic composites and salts. Physical chemistry investigates the interactions between molecules and ions within a particular material, the rate and mechanism of a chemical reaction and energy transfers during reactions.

We use rechargeable batteries almost every day now, in our mobile phones and laptop computers, without thinking twice about them. N Munichandraiah and his lab work on rechargeable lithium-ion batteries and other low cost, efficient materials that can provide cheap clean energy in the future, like novel polymers.

Polymers are extremely large molecules made of repeating smaller units. Polythene is the most common example — it’s actually polyethylene, and is made of repeating units of ethylene, a hydrocarbon similar to methane. S Ramakrishnan and his group focus on the synthesis and study of polymers and their properties.

Organometallic complexes, which contain a metal ion along with biomolecules like proteins, are involved in the body’s biochemical pathways. Akhil Chakravarty’s group designs complexes that are toxic to cells, which can be used to stop the spread of tumours. B R Jagirdar’s laboratory also works on organometallic compounds, focussing more on how they catalyse different reactions. The group also works on materials chemistry, including research into materials that can be used for storing hydrogen. Metalloproteins are proteins with a metal ion in them, like the oxygen carrier haemoglobin in our blood, which contains iron. G Mugesh and his group are developing methods to mimic the activity of metalloprotein enzymes. A G Samuelson works on “metallo-drugs” — organometallic compounds that can be possible therapeutics. They have identified a complex containing copper that is especially active against tumour cells.

The nano scale forms the premise for P S Mukherjee’s lab. Enhancing reactivity of materials by bringing them together in an enclosed space — something similar to what enzymes do — is one focus of research. Another is to make magnetic nanoparticles even smaller — this can increase the ability of storage devices like your hard drive to store data.

E Arunan studies weak inter-molecular forces called Van der Waals forces. The group also works on rates of chemical reactions - why they occur, how to predict their behaviour and the rate at which they occur. Atanu Bhattacharya works on special kinds of chemical reactions which involve materials in their gaseous state. The group observes the fate of the chemicals involved at a very fine time scale — one-trillionth of a second or less. P Thilagar’s group uses an interdisciplinary approach to design new molecules and materials, to be used as catalysts, for chemosensory applications and in electronics.

S Sampath has been working on surface chemistry — the behaviour of solid-solid and solid-liquid interfaces. Batteries are a good example, where metals and in contact with a liquid medium. Prof. K. L. Sebastian’s group work on building theoretical models for various intermolecular processes using both statistical mechanics and quantum mechanics. S Vasudevan’s group works in the area of physical chemistry and spectroscopy of materials with special emphasis on layered solids and porous materials.

Siva Umapathy’s group uses a technique called spectroscopy to study molecular structure. Light with wavelength comparable to the size of molecules (about ten million times smaller than a millimetre) is used to obtain information like molecular weight and arrangement of component units. The group uses Raman spectroscopic techniques to probe a variety of phenomena in molecules and materials. M Nethaji uses X-ray crystallography to study molecular structure. When a beam of X-rays hit a crystal, they get “diffracted” into characteristic patterns, which can be studied to understand the structure of the crystal.

By training a laser beam on a sample, P K Das and his group study specific properties (nonlinear optical properties) of molecules and materials. They are working on detecting atmospheric pollutants like polycyclic aromatic hydrocarbons (PAHs) in very small concentrations using infrared spectroscopy; they are also working on nanoparticle based sensors that can detect diseases and toxic chemicals.

E D Jemmis and his group use theoretical techniques (like quantum theory) to study molecules and materials with unusual bonding. Binny Cherayil’s group uses theoretical models to describe how biomolecules influence cellular events. For instance, in reactions involving proteins, a change in the three dimensional structure can influence the rate of the reaction. Sai Ramesh and his group use computer simulation to understand different processes like the role of a solvent in a chemical reaction or photochemistry of small molecules. Upendra Harbola and his group work on many body quantum calculation to understand electron flow in molecules.

Debasish Manna from G Murugesh’s lab has written a paper discussing the synthesis,  structure and mechanism of action of thyroid hormones, including physiological conditions that result from under and overproduction of the hormone (Accounts of Chemical Research; doi: 10.1021/ar4001229).

Rajesh Chalasani and Sukumaran Vasudevan have developed “capture and destroy” nanomaterials, which can destroy toxic materials like bisphenol A (Bis-A). Bis-A can  mimic naturally occurring hormones in the human body and disrupt regular function. Made of iron oxide and titanium dioxide, these materials can be recovered after they clean up water, making them recyclable.