Solvent effect and amine interference on colorimetric changes of azobenzene-conjugated dithiaazadioxo crown ether mercury sensor

Abstract The colorimetric behavior of an azobenzene-based dye containing dithiaazadioxo ring for Hg 2+ -detection was investigated in diverse solvents. The mercury specific ligand shows hypsochromic changes in pure and aqueous MeCN upon Hg 2+ -binding while strong bathochromic shift was observed in chloroform. In both solvent systems, dithiaazadioxo ring is revealed to be indispensable to the selective detection of mercury ion, and several binding schemes in different solvents were proposed on the selective Hg 2+ binding. Grafted on cationic polymer (PEI) through amide coupling, it was observed that the ligand basically maintains the Hg 2+ detection capability, but substantially hindered by amine moieties in PEI.