Attachment of electron-withdrawing 2,4-dinitrobenzene groups to a cryptand-based receptor for Cu(II)/H<SUP>+</SUP>-specific exciplex and monomer emissions

In a cryptand-based fluorescent signaling system with the configuration "fluorophore-spacer-receptor", attachment of the electron-withdrawing 2,4-dinitrobenzene groups to the cryptand receptor renders it highly selective for Cu(II). The system exhibits dual monomer and exciplex emissions in the presence of either of Cu(II) and H+ as input with concomitant movements of one of the 2,4-dinitrobenzene groups