A novel class of sulphonate group containing unsymmetrical squaraine dyes has been synthesized. These dyes show a selective and sensitive affinity towards Hg2+ in methanol and are practically insensitive to most other environmentally and biologically relevant metal ions. Isothermal titration calorimetric (ITC) studies and High Resolution Mass Spectral (HRMS) analysis indicate a 1: 1 binding mode. 1H and 13C NMR of the isolated Dye… ...