 As each molecule can give rise to a signal/readout, that can be selectively measured, chemosensors are often said to be non-invasive and consequently have attracted significant attentions for their applications within biological matter, such as within living cells.Many examples of chemosensors have been developed for observing cellular function and properties, including monitoring ion flux concentrations and transports within cells such as Ca(II), Zn(II), Cu(II) and other physiologically important cations and anions, as well as biomolecules.The design of ligands for the selective recognition of suitable guests such as metal cations and anions has been an important goal of supramolecular chemistry.