Boronic acid-linked fluorescent and colorimetric probes for copper ions

The first examples of boronic acid-linked fluorescent and colorimetric chemosensors for copper ions are reported; the monoboronic acid-conjugated rhodamine probe displays a highly selective fluorescent enhancement with Cu2+ among the various metal ions whereas the fluorescence of the bisboronic acid-conjugated fluorescein probe is selectively quenched by Cu2+, probably by way of a PET mechanism.