Unsymmetric dendrimers containing a single ureidopyrimidine unit: Generation-dependent dimerization via hydrogen bonding

A new series of unsymmetric Newkome-type dendrimers have been prepared and characterized. These dendrimers contain a single ureidopyrimidine residue covalently attached to their apical positions. In low polarity solvents, the first and second generation dendrimers form highly stable dimers via hydrogen bonding of their AADD ureidopyrimidine units, whereas the third generation dendrimer dimerizes to a very low extent.