Highly Sensitive Fluorescent Probes for Zinc Ion Based on Triazolyl-Containing Tetradentate Coordination Motifs

Two new 1,2,3-triazolyl-containing N4-tetradentate ligands show nanomolar affinity for Zn2+ under physiological conditions. Furthermore, they are easily derivatizable to afford fluorescent probes suitable for sensitive Zn2+ detection. Structural characterizations in both solid and solution states suggest that N3 and N2 in the 1,2,3-triazolyl moiety coordinate with Zn2+ in A and B to afford five-membered and six-membered coordination rings, respectively. The probes show sensitive fluorescence enhancement and ratiometric responses to Zn2+.