A　series　of　new　ruthenium(II)　polypyridine　complexes　appending　with　thioether　groups　were　designed,　synthesized　and　characterized.　The　sensing　ability　of　the　complexes　toward　mercury　ions　were　studied　by　electronic　absorption　and　emission　spectra,　and　the　reaction　of　the　complexes　with　mercury　ions　were　also　confirmed　by　ESI　mass　spectroscopy　and　(HNMR)-H-1　spectroscopy.　The　thioether　groups　would　react　with　mercury　ion　fast　to　form　aldehyde　group　leading　to　the　significant　change　in　the　spectra.　The　color　of　the　complex　changed　from　yellow　to　orange　after　addition　of　mercury　ions,　and　the　color　of　the　emission　changed　from　red　orange　to　dark　red　with　a　large　red　shift　(similar　to　80　nm).　Importantly,　these　kinds　of　ruthenium(II)　complexes　show　a　unique　recognition　of　mercury　ions　over　other　metal　ions.　The　complexes　with　more　thioether　groups　also　showed　a　better　sensitivity　toward　mercury　ions,　this　is　good　strategy　for　the　further　design　of　the　new　phosphorescent　probes　for　sensing　of　mercury　ions.　(C)　2019　Elsevier　B.V.　All　rights　reserved.