Computational study of the complexation of metal ion precursors in dendritic polymers

Metal ions are important for medical, environmental and catalytic applications. They are used as precursor molecules for the manufacture of metal nanocatalysts, which are promising materials for an array of biomedical, industrial, and technological applications. Understanding the effect of the environment upon a metal ion-dendrimer system constitutes a step closer to the understanding of the liquid phase templated synthesis of metal nanoparticles. In this dissertation we have used computational techniques such as abinitio calculations and molecular dynamics (MD) simulations to investigate the complexation of Cu(II) and Pt(II) metal ions to a polyamidoamine (PAMAM) dendritic polymer from structural, thermodynamic, and kinetic viewpoints. First, we analyze the local configuration of a low generation polyamidoamine dendrimer to understand the role of intramolecular interactions. Then, we examine the local configuration of dendrimer outer pockets in order to determine their capacity to encapsulate water within. Next, the complexation of Cu(II) with a small ?OH terminated dendrimer in presence of solvent and counterions is investigated. This relatively simple system gives insight on how cationic species bind within a dendrimer. The complexation of potassium tetrachloroplatinate, commonly used precursor salt in dendrimer templated synthesis of platinum and bimetallic platinum-containing nanoparticles, with PAMAM dendrimer has been the subject of several experimental reports. So we investigate the complexation of potassium tetrachloroplatinate within a dendrimer outer pocket in order to understand the effect of dendrimer branches, Pt(II) speciation, pH, solvent and counterions upon it. Our study shows that dendrimer branches can improve the thermodynamics but can also preclude the kinetics by raising the energy barriers. Our study provides an explanation of why, where Pt(II) and how Pt(II) binds. We believe that these molecular level details, unaccessible to experimental techniques, can be a helpful contribution toward furthering our understanding of the complexation of Pt(II) and the starting point to study the next step of dendrimer templated synthesis, the reduction of Pt(II) into platinum nanoparticles inside pockets.