benefit of the world at large and developing world in particular. Along with such studies, he pursued fundamental problems of relevance to the science of ice surfaces. For studies of ultrathin surfaces of molecular solids such as ices, he developed unique instrumentation, an important aspect of his research. Pradeep discovered several atomically precise clusters or nano molecules of noble metals. These are molecules composed of a few atom cores, protected with ligands, especially thiols which are fundamentally different from their bulk and plasmonic analogues in terms of their optical, electronic, and structural properties. Such clusters show distinct absorption spectra and well-defined luminescence, mostly in the visible and near-infrared regions, just as molecules. He introduced several new synthetic approaches to make new clusters (a summary of the methods is presented in reference), showed some of the very first examples of chemistry with such materials and developed applications with them. Most recent of these examples is the introduction of inter-cluster reactions between clusters, which demonstrate that nanoparticles behave like simple molecules and stoichiometric reactions of the type, A + B → C + D, can be written for these processes, where A, B, C and D are nanoparticles. To describe the structure and properties of such clusters, his group has introduced a system of nomenclature for such systems in general. This kind of chemistry performed with isotopically pure nanoparticles of the same metal has shown that metal atoms in nanoparticles undergo rapid exchange in solution as in the case of water. The important atomically precise clusters he discovered are: Ag7/8, Ag9, Au23, Ag152 and the smallest molecular alloy, Ag7Au6. He created methods to form highly uniform nanotriangles and introduced a new family of materials called mesoflowers. Combining luminescent atomically precise clusters with mesoflowers and nanofibres, he developed sensors at sub-zeptomole levels which are probably the limits of fast molecular detection. A single mesoflower has been shown to detect nine molecules of trinitrotoluene (TNT). A recent example of this chemistry is the detection of 80 ions of Hg2+ with single nanofibers. A number of atomically precise luminescent clusters have been made in proteins and their growth involves inter-protein metal transfer. These clusters were shown to be excellent biolabels. Early examples of cluster functionalisation were demonstrated by him and the methods he introduced are shown to impart properties such as fluorescence resonance energy transfer to such systems and these methodologies are now used for