Organometallic photonucleases: synthesis and DNA-cleavage studies of cyclopentadienyl metal-substituted dendrimers designed to increase double-strand scission.

[reaction: see text] A series of metal complex-substituted polyamine dendrimers have been synthesized and examined for their ability to cleave plasmid DNA in a double-stranded manner. While photolysis of the dimetallic spermine derivative and the tetrametallic DAB-Am-4 complex led to double-strand scission, in the larger DAB-Am-8 and DAB-Am-16 systems, DNA aggregation/precipitation was the predominant competing process observed.