A new chemosensor (L1) is synthesized and its spectral response were screened with most alkali, alkaline earth,transtion and lanthanide meatl ions in THF-water (2:3, v/v, pH 7.2, 20mM HEPES buffer) medium. This is found to bind four different transition metal ions such as Hg2+, Cu2+, Ag+ and Ni2+ in mixed aqueous solution at neutral pH; while binding affinity towards the Hg2+ is found to be an order of magnitude higher as compared to other three cations mentioned. Experimental results reveal that the L1 could be used for colorimetric detection of Hg2+, present in the lower organism like Pseudomonas putida

A tetrapyrrole-based chromophore was obtained through the methanolysis of C-phycocyanin extracted from Spirulina platensis, and was found to act as a selective receptor for Hg2+ at physiological pH conditions.