Synthesis of highly functionalised dendrimers based on polyhedral silsesquioxane cores

A number of dendrimers based on polyhedral silsesquioxane cores have been synthesised and characterised. The new molecules are prepared by repetitive hydrosilation/alkenylation reactions, which provide a facile and high yield route to dendrimers with a high density of branch ends per generation. Judicious choice of hydrosilating agent [HSiCl3, H(CH3)SiCl2 or H(CH3)(2)SiCl] produces dendrimers with varying numbers of chain ends, and alkenylating agents of different lengths produce molecules with different physical properties. The 24-vinyl functionalised dendrimer, 5, has been characterised using single-crystal X-ray diffraction techniques.