Colorimetric metal ion sensors - A comprehensive review of the years 2011-2016

A chemosensor is a synthetic chemical system which is capable of binding with an analyte in a selective and reversible manner followed by change in one or more properties of the system in the form of color or fluorescence or redox potentials. The choice of a chromophore has tremendous effect on these properties. The well established and indispensable role of metal ions in connection to their medicinal, biological and environmental concern makes their sensing one of the major research domains out of other domains including detection of anions, bio molecules, pesticides, explosives, etc. Therefore, the number of research articles is growing at a high rate dedicated to pave path for more reliable and sophisticated chemosensors. In this context, continuous compilation of research work is highly desirable (or acceptable) in order to generate a library of chromophores helping the budding researchers to access the present trends in limited (short) time. In this review, we have focused on colorimetric sensors for metal ions, viz. alkali and alkaline earth, Al3+, Cr3+, Mn2+, Fe3+/Fe2+, Co2+, Ni2+, Cu2+, Zn2+/Cd2+, Hg2+, Ag+, Sn4+/Sn2+, Pd2+, Pb2+, Zr4+, Mo6+, due to their numerous advantages such as, easy detection without requiring sophisticated instruments, high selectivity and sensitivity in terms of different color change for different species, over other chemosensors. This work is a comprehensive survey of colorimetric sensors for metal ions developed in the years from 2011 to 2016 (>450 references).