Supra-molecular chemistry, conceptually founded as a research field in its own in the 1960s is a rapidly growing field at the borderline of several disciplines such as bio(organic) chemistry, material sciences and certainly the classical chemistry topics, i.e. (in) organic and physical chemistry. Selective binding of ions is an important area of supra-molecular chemistry research in terms of ion detection, transport and sensing. Currently, there is a surge of interest in the development of tailor-made sensor molecules, able to act as chromogenic sensors for a specific analyte as colorimetric sensors are simple-to-use diagnostic tools for sensing purposes that allow 'naked eye' detection of ions without resort to any spectroscopic instrumentation. In this book, the detailed photophysical studies of anthracene-9,10-diones bearing electron-rich coordinating sites at 1 / 1,8 or 1,4 positions for metal ions through color change have been elaborated. Also, the paradigm shift from selective to differential receptors has been used for single molecular receptor based simultaneous analysis of multiple analytes.