When Design Meets Function: The Prodigious Role of Surface Ligands in Regulating Nanoparticle Chemistry

The underlying power of “interplay of forces” in controlling the properties and functions at the nanoscale is highlighted in this perspective. This interplay is achieved by installing attractive and repulsive forces, via proper ligand chemistry, which will guide the nanomaterials to interact with their surroundings as per the need. Along with improving the existing properties, the balancing of attractive and repulsive forces holds the prospects of imparting newer functions as well. The concept of “ligand-directed interplay of forces” is extensively practiced by our group and others for addressing many challenges in the areas of self-assembly, catalysis, light harvesting, and nanomedicine. The journey has been rewarding so far in terms of achieving many important feats in nanoscience, such as self-assembly under equilibrium and nonequilibrium regimes, outplaying ligand poisoning in nanocatalysis, channelizing the flow of energy and electron in donor–acceptor systems, multicolor photopatterning using a single nanohybrid system, biospecific targeting and therapy, and so on. As evident from this perspective, the diversity of the areas benefited showcases the breadth and depth of the impact that surface ligands and interplay of forces can have in material science. Furthermore, the implementation of the “ligand of choice” approach is one way to realize distinct and specific functions from a limited set of nanomaterials. All the examples of “ligand-directed studies” mentioned in this perspective are based on the regulation of, primarily, electrostatic forces emanating from the charged surface ligands. Thus, it will be logical to try various combinations of ligands and forces, which means that the area of “ligand-directed nanochemistry” will keep on advancing beyond our predictions. Looking forward, there is plenty of room at the NP surface.