Interaction Mechanism of Nano-silicon Dioxide Modified by Poly(amidoamine) Dendrimers

To gain insight into the attachment of ≡Si⁺ (SC) ion (regarded as guest) to the lowest generation, NH₂-terminated poly(amidoamine) (PAMAM) dendrimers (regarded as host) in the liquid phase, density functional theory is used to investigate the structures and energetics of the host-guest complex. The effect of solvent on the structures and energetics is also investigated. Various initial configurations of the ion bound to PAMAM are tested, and two stable conformers are found, i.e, types A (≡Si⁺ is bound to the amine site) and C (≡Si⁺ is bound to the amide site). Types A and C are the most stable due to the chemical bond formations of Si-No(amine nitrogen atoms) and Si-O, respectively. The IR spectra for the lowest energy conformers are thoroughly analyzed and compared with the available experimental data.