Molecular Dynamics of Lysine Dendrimers. Computer Simulation and NMR

In this chapter we describe application of the method of molecular dynamics (MD) for the computer simulation of the poly‐L‐lysine dendrimers of different generations and at different temperatures. These dendrimers differ from other dendrimers by asymmetric branching which could influence the size and shape of dendrimer as well as their dynamical properties. In particular we have shown that the linear spacers between neighboring branch points in all lysine dendrimers are strongly extended and the angles between short spacers are almost fixed. Due to these reasons the lysine dendrimers are rather rigid and their structural characteristics almost do not dependent on temperature. The dynamical characteristics of lysine dendrimers obtained by MD and NMR methods agree rather well. It was obtained that the local mobility of inner CH₂ groups is smaller than mobility of corresponding terminal groups in agreement with our previous results for the flexible dendrimers. At the same time local orientation mobility of the internal groups depends on the number of generations in lysine dendrimer. This behavior differs from the behavior of flexible dendrimers in which the internal mobility is practically the same for the dendrimers of different generations.