A new sensor 2-((E)-(3-(1H-imidazol-1-yl)propylimino)methyl)-5- (diethylamino)phenol (1) based on the combination of diethylaminosalicylaldehyde and imidazole groups was designed and synthesized as a Hg2 + selective colorimetric chemosensor. Upon treatment of 1 with mercury ions, sensor 1 showed a color-change from colorless to yellow in a mixture of H 2O/DMF (5:95), while many other ions such as Al3 +, Zn2 +, Cd2 +, Cu2 +, Fe2 +, Mg 2 +, Cr3 +, Ag+, Co2 +, Ni 2 +, Na+, K+, Ca2 +, Mn 2 + and Pb2 + had no influence. Notably, this chemosensor could distinguish clearly Hg2 + from Cu2 +, Ag +, Fe2 + and Pb2 +. The underlying signaling mechanism is a ligand-to-metal charge-transfer (LMCT) process. Compound 1 showed the serial formation of the 1:1 and the 1:2 complexation between 1 and Hg 2 +. This two-step binding mode was proposed based on the UV titration, 1H NMR titration and ESI-mass studies.
Bibliographical noteFunding Information:
Financial support from Nowon Institute of Science Education for the Gifted and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Korean Ministry of Education, Science and Technology ( 2012001725 , 2011K000675 , and 2012008875 ) is gratefully acknowledged.
- LMCT process
- Mercury ion
- Naked-eye detection