Chemosensors describes molecule of synthetic origin that signal the presence of matter or energy. A chemosensor can be considered as type of an analytical device. Chemosensors are used in everyday life and have been applied to various areas such as in chemistry, biochemistry, immunology, physiology, etc. A key requirement of chemosensor function is that analyte binding must occur reversibly thereby analyte concentration can be measured at equilibrium by optical detection of either the chemosensor-bound species or the analyte-free chemosensor. It also permits monitoring dynamic optical response to changing analyte concentrations. Reversible association between the chemosensor and its analyte is a very applicable phenomenon.