A　novel　naphthalene-2,3-diamine-2-salicylaldehyde　(NS)　ligand　and　its　mononuclear　copper(II)　complex　(CuNS)　have　been　synthesized　and　structurally　characterized.　The　UV-vis　absorption　and　emission　spectra　of　NS　showed　obvious　changes　on　addition　of　Cu2+　solution.　The　interaction　of　the　compounds　with　calf　thymus　DNA　and　G-quadruplex　DNA　were　investigated　by　spectroscopic　methods　and　thermal　melting　assay.　The　nucleolytic　cleavage　activity　of　the　compounds　was　investigated　on　double-stranded　circular　pBR322　plasmid　DNA　and　G-quadruplex　DNA　by　electrophoretic　mobility　shift　assay.　The　results　show　that　CuNS　has　a　greater　ability　to　stabilize　G-quadruplex　DNA　over　calf-thymus　DNA.　The　cytotoxicity　of　the　compounds　toward　HpeG2　cancer　cells　was　also　studied,　and　they　showed　significant　potential　for　antineoplastic　effects.