Azacrown[N,S,O]-modified porphyrin sensor for detection of Ag+, Pb2+, and Cu2+†
One new azacrown[N,S,O]-modified metal-free porphyrin derivative, H2Por-azacrown (1), with the central tetrapyrrole moiety as signaling fluorophore and/or metal ion receptor has been designed, synthesized, and characterized. Addition of Ag+ into this novel metal-free porphyrin compound induces a fluorescence ON–OFF process, while adding Pb2+ leads to absorption/emission-ratiometric signals. Quite interestingly, blue-shift of the Soret band, ratiometric change of Q bands, and dual-signal changes (absorption ratio and fluorescence ON–OFF) associated with the Cu2+ displacement from the 1–Pb2+ system were observed upon addition of Cu2+. These results render this H2Por-azacrown compound a porphyrin-based multi-responsive optical sensor towards Ag+, Pb2+, and in particular Cu2+ with dual-mode detecting potential.