Chemical Crystallography and Materials Design High resolution non ambient X-ray diffraction studies aimed at understanding the nature of chemical bonding on a quantitative basis forms the central theme of research of our group. The offshoot of such studies generate design elements required for realizing components which could be put to practice to obtain novel functional materials. The phase behavior of such materials (both organic and inorganic origin) offers to generate a variety of hitherto unexplored materials. Experimental and theoretical charge density studies provide a quantitative basis to unravel intra- and intermolecular interactions involving group IV to group VII elements in terms of the so called sigma-hole formalism. The topological analysis followed by interaction energy calculations point to a common platform for all such intermolecular interactions, for example halogen bonding, chalcogen bonding, pnicogen bonding and carbon (tetral) bonding. Studies using variable temperature X-ray diffraction techniques on selected hydrated minerals offer an understanding of phase separation upon dehydration leading to (i) generation of futuristic materials and (ii) pathways of mineral evolution. Co-crystallization to explore organic molecule crystal form diversity including solvates, solid solutions, eutectics, salts, ionic liquids, solid dispersions and supramolecular gelators with particular emphasis on cocrystals and eutectics. The inputs allow for (i) design of functional materials displaying ferroelectric, dielectric and ionic and proton conducting behaviour; (ii) improvisation in the performance of active pharmaceutical ingredients(APIs). Design of small molecule inhibitors (potent and highly selective) to block C-Jun-N-terminal Kinase (a key component in the cell signaling pathway) as a preliminary step to prevent cancer proliferation in cells is being pursued in collaboration with biological sciences division. In situ cryo crystallography techniques are employed to obtain useful hints on polymorphism, polytypism in molecular crystals, which are necessary inputs to unravel pathways to crystal growth mechanisms.