3,5-dihydroxybenzylalcohol based dendrimers: structure evaluation and molecular encapsulation in generations 1-5

摘要

Geometric characterization of 3,5-dihydroxybenzyl alcohol (DHBA)-based dendrimers has been achieved using molecular mechanics MM+ method and the PM3 semi-empirical molecular orbital theory. Optimization of DHBA-based dendrimer generations 1-5 (DG1-5) showed that DG1-3 have a relatively open structure with no internal spaces of any particular size or shape, while DG4 and 5 assume a more globular structure with well-defined internal cavities. Encapsulation of disperse red 1 (DR1) into the cavities of these dimethylsilyl linked DHBA-based dendrimers led to a blue shift in the lambda(max) of DR1, and transmission electron microscopy (TEM) showed a rectangular shape of dendritic aggregates containing DR1. Catalytic activity of (COD)RhCl(PPh2(CH2)(3)OH) encapsulated in dendritic aggregates below and above critical aggregation concentration (cac) of generations 1-4 was examined. A significant decrease in catalytic conversion of 1-decene to decane in dendrimer generations 4 upon going from a concentration below cac to above cac was observed.