Construction of fluorescent probes via protection/deprotection of functional groups: a ratiometric fluorescent probe for Cu2+.

Herein a ratiometric fluorescent Cu(2+) probe was rationally constructed in a straightforward manner with the concept of aldehyde group protection/deprotection. The probe showed a ratiometric fluorescent response to Cu(2+) with a large emission wavelength shift (>100 nm) and displayed high selectivity for Cu(2+) over other metal ions due to distinct deprotection conditions. In addition, a Cu(2+)-promoted dethioacetalization mechanism was proposed.