Triazolyl Alkoxy Fischer Carbene Complexes in Conjugationwith Ferrocene/Pyrene as Sensory Units: Multifunctional Chemosensorsfor Lead(II), Copper(II), and Zinc(II) Ions.

Theregioselective 1,3-dipolar cycloaddition reaction of alkoxyalkynyl Fischer carbene complex 1with azidomethyl ferrocene 2and with azidomethyl pyrene 4under solvent-freeconditions yielded the triazolyl Fischer carbene complexes 3(C27H21O6N3FeW) and 5(C33H21O6N3W),respectively. The cation complexation properties of these receptorshave been systematically studied using electrochemical and spectroscopictechniques. The exceptional structural feature existing in these receptorsis the presence of a Fischer carbene moiety, connected to the ferroceneor pyrene moiety through a 1,2,3-triazole ring. Receptor 3contains a redox-active ferrocene moiety and is highly selectivetoward Pb2+ion, whereas receptor 5, havinga fluorescent pyrene unit, selectively recognizes Zn2+andCu2+ions. The binding ability of receptor 3can be inferred either from the redox shift (the anodic shift ΔE1/2= 55 mV) or the highly visual output responsefor Pb2+ion. Receptor 5displays considerablechelation-enhanced fluorescence (CHEF) upon binding with Zn2+and Cu2+ions in an aqueous environment. Further, theproposed binding modes of these receptors and their metal cation complexationproperties have been supported by 1H NMR titration andMALDI-MS and a DFT study. [ABSTRACT FROM AUTHOR]