applications. Cluster functionalisation chemistry has recently been extended to make isomers of nanomolecules and these have been isolated in collaboration with Japanese scientists. He has recently demonstrated supramolecular functionalisation of clusters. Such clusters help assemble 1D nanostructures, leading to precise 3D structures. Simple methods of synthesis and analysis have been some of the focal themes of his research. In a recent work, molecular ionization was demonstrated at 1 V from a carbon nanotubes-impregnated paper. This methodology was used to collect high quality mass spectra of diverse analytes. Besides the advantage of low internal energy of the ions, which preserves fragile species and intermediates, the methodology helps in miniaturising mass spectrometry. Ion-based chemistry is now used to synthesise structures such as metal grasslands, extending over cm2 areas. He discovered noble metal nanoparticle-based drinking water purification methods and developed the world's first drinking water filters utilising nanochemistry. The chemistry he developed was reductive dehalogenation of halocarbons at noble metal nanoparticle surfaces which when applied to several of the common pesticides present in surface waters of India, resulted in their degradation at room temperature and extremely low concentrations, of the order of parts per billion. The process when occurs on supported nanoparticles, trace concentrations of halocarbon pesticides can be removed from a flowing water stream. Water purifiers based on this technology have been introduced in the market since 2007. As a result of this innovation, many activities have started in India and elsewhere and we are now certain of the impact of nanomaterials in clean water. About 1.5 million of these filters have been sold in the market till 2016. IIT Madras received over Rs. 230 lakhs in royalties from this finding, the first of its kind in the Indian university system, in terms of royalty earnings and reach from a single patent. He developed several new technologies in the recent past to tackle various other contaminants such as arsenic, lead, mercury and organics in water, which are the subject of a few issued and filed patents. Such capabilities to bring contaminant concentrations under drinking water norms using diverse nanomaterials, feasible synthesis of such materials in quantities, creation of viable processes for their implementation along with the use of efficient sensors would make clean drinking water affordable using nanomaterials. A critical problem in achieving this goal is the development of advanced and affordable materials with no or reduced environmental impact. Some of the