A newchromogenicreceptor,4-((2,4-dichlorophenyl)diazenyl)2-(3-hydroxypropylimino)methyl) phenol, hasbeendesignedandsynthesizedforquantitativeandlow-costdetectionofvariousbiological anions andcations.Thedyewascharacterizedbyelementalanalyses,infrared,UV–visible spectroscopy, and NMRspectroscopy.UpontheadditionofF and H2PO4 to thesolutionofchemosensorinDMSO, the dramaticnakedeyedetectablecolorchangeswereobservedfromyellowtoredandorangewitha limit ofdetection(LOD)of1.66106 mol. L1 and 1.24106 mol. L1 at roomtemperature,re- spectively.Thechemosensorshowedvisualchangestowardscations,suchasAl3þ, Cu2þ, Fe3þ, andCr3þ, in DMSO/water(9:1).Thedetectionlimitofreceptor L for theanalysisofAl3þ ion wascalculatedtobe 3.02106 mol. L1. Theanionrecognitionpropertyofthereceptorviaprotontransferwasmonitored by UV–visible titrationand 1HNMR spectroscopy.Thebindingconstant(Ka) andstoichiometryofthe host–guest complexesformedweredeterminedbytheBenesi–Hildebrand (B–H) plotandJob'smethod,
