A　novel　fluorescence　sensor　was　designed　and　synthesized　for　detecting　Cu2+　with　high　sensitivity　and　selectivity.　The　sensor　showed　a　large　red-shift　in　UV-vis　spectra　and　obvious　decline　of　fluorescent　intensity　in　fluorescence　emission　spectra　upon　the　addition　of　Cu2+.　Bio-imaging　studies　and　flow　cytometric　analysis　revealed　that　this　sensor　was　cell-permeable　and　could　be　used　for　detection　of　changes　of　intracellular　Cu2+,　suggesting　the　suitability　of　this　sensor　for　biological　application.　Cell　cytotoxicity　studies　demonstrated　it　was　capable　of　chelating　excess　Cu2+in　vitro　to　modulate　the　biological　functions　of　Cu2+　with　low　cytotoxicity.　Therefore,　this　compound　could　be　a　promising　fluorescent　sensor　combining　the　abilities　of　either　detection　or　modulation　of　the　biological　function　of　Cu2+　in　biological　conditions.　©　2015　The　Royal　Society　of　Chemistry.