The Cl replacement reactions of hexachlorocyclotriphosphazene (trimer; N3P3Cl6) with sodium (N-benzyl)aminopropanoxides (1 and 2) produced monospiro- (3 and 4), cis-, and trans-dispirocyclotriphosphazenes (13-16). The monospiro tetrakis-aminocyclotriphosphazenes (5-12) were obtained by the Cl substitutions of 3 and 4 with different secondary amines. The cis- (13 and 14) and trans-dispirophosphazenes (15 and 16) possessed 2 chiral P centers, and they were able to present meso and racemic forms, respectively. Moreover, the structures of compounds 5 and 14 were designated using X-ray data. The absolute configuration of compound 14 was found as SR in the solid state. Analytical and spectroscopic data of the phosphazenes were consistent with their suggested structures. Antimicrobial activities of the benzyl-pendant-armed cyclotriphosphazenes were scrutinized against G(+) and G(-) bacteria and yeast strains. The bacterium most affected by the synthesized compounds was Pseudomonas aeruginosa. Minimum inhibitory concentrations and minimal bacterial concentrations were in the range of 125-500 mu M. Interactions between the phosphazenes (3-12 and 15) and plasmid DNA were studied with agarose gel electrophoresis. The phosphazeneDNA interaction studies of the cyclotriphosphazenes revealed that phosphazenes 3, 4, and 15 had a substantial effect on supercoiled DNA by cleavage of the double helix.