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　Hg　2+　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　Hg　2+　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　μM　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,　1H　NMR　and　IR　titration　showed　that　a　1:1　complex　was　formed　between　squaraine　and　Hg2+　ion.　©　2014　Elsevier　B.V.