Herein,　we　present　an　effective　strategy　based　on　coordination　induced　deaggregation　signaling　to　create　water-soluble　fluorescent　probes　for　the　detection　of　mercury　ion　by　introducing　the　thioether　group　linkage　into　squaraine-aniline　dyads.　Three　unsymmetrical　squaraine　dyes　tethered　with　thiopodand　chains　in　different　length　were　synthesized　accordingly.　The　deaggregation　process　of　the　aggregated　squaraine　dyes　triggered　by　Hg2+　was　elucidated　in　detail.　Firstly,　the　aggregation　behavior　of　squaraine　dyes　with　varying　thioether　chains　in　aqueous　solutions　has　been　investigated.　Secondly,　the　complexation　ability　of　squaraines　with　Hg2+　was　found　to　be　strengthened　by　increasing　the　length　of　the　thioether　chain.　Additionally,　an　aggregated　squaraine　solution　was　designed　by　adding　trace　amount　of　non-ionic　surfactant　to　solubilize　the　dye　in　pure　water　for　the　detection　of　Hg2+.　Significantly,　the　aggregated　state　of　squaraine　molecules　was　selectively　broken　by　Hg2+　ions　despite　a　wide　range　of　other　interfering　metals　in　water　media.　Under　optimum　conditions,　the　fluorescence　recovery　was　linearly　proportional　to　the　concentration　of　Hg2+　between　0.03　and　1.8　mu　M　and　the　detection　limit　was　as　low　as　6.6　nM　(1.3　ppb).　Further　study　of　the　mechanism　by　absorption　and　emission　spectroscopy,　MS,　H-1　NMR　and　IR　titration　showed　that　a　1:　1　complex　was　formed　between　squaraine　and　Hg2+　ion.　(C)　2014　Elsevier　B.V.　All　rights　reserved.