Azacrown[N,S,O]-modified porphyrin sensor for detection of Ag+, Pb2+, and Cu2+

Abstract

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.