Interaction mechanisms between poly(amido-amine) and nano-silicon dioxide

摘要

To gain insight into the attachment of iSi~+ (SC) and iFSiO ~- (SOA) ions (regarded as guests) to the lowest generation, -NH _2-terminated poly(amidoamine) (PAMAM) dendrimers (regarded as host) in the gas phase, density functional theory is used to investigate the structures and energetics of the complexes with B3LYP/6-31+G (d) and HF/6-31G basis sets. The initial parameters are obtained through the initial optimizations at the HF level using the most basic STO-3G basis set. Various initial configurations of the ions bound to PAMAM are tested, and four stable conformers are found, i.e., types A to D. Types 1A and 2C are the most stable due to the chemical bond formations of Si-N° and Si-O, respectively. For type B, SC coordination to amide O sites occurs via electrostatic induction. For type D, SOA coordination to amide hydrogen and amine hydrogen sites occurs via hydrogen bond interaction. Spatial hindrance, electrostatic induction force, and hydrogen-bond interaction play important roles in the complexation process.