New ferrocene-triazole derivatives for multisignaling detection of Cu2+ in aqueous medium and their antibacterial activity.

Ferrocene-based naphthalene or quinoline receptors 1-4 linked by triazole were designed and synthesized. Their recognition properties of metal cations have been investigated systematically in aqueous environment. Upon addition 1 equiv. of Cu2+ ion, receptors 1 (C23H19FeN3O) and 2 (C22H18FeN4O) showed fluorescent turn-off, enhanced absorption and color variations. At the same time, receptor 1 also caused the perturbation of redox potential after addition 1 equiv. of Cu2+ ion. Therefore, receptors 1 and 2 behaved as naked-eye chemosensors and fluorescent probes for Cu2+ without interference by other ions and with low detection limit. In addition, receptor 1 could also be considered electrochemical sensor for Cu2+ having excellent sensitivity and selectivity. However, increasing the molecules flexibility resulted in the lower selectivity of ion recognition in the case of receptors 3 (C24H21FeN3O) and 4 (C23H20FeN4O). Furthermore, this series of compounds were nontoxicity and receptor 1 exhibited certain antibacterial activity.