Synthesis of 2,5-Substituted Siloles and Optical Study of Interactions with Mercury(II), Copper(II), and Nickel(II) Cations

Several 2,5-diaryl-1,1-dimethyl-3,4-diphenylsiloles (with aryl = p-cyanophenyl (1), m,p-bis­(methylthio)­phenyl (2), p-N,N-dimethylaminophenyl (3), 2,2′-bipyridin-6-yl (4)) were synthesized and characterized by UV–vis, fluorescence, and NMR spectroscopy, along with crystal structure determinations for 1 and 2. Compounds 1–4 in methylene chloride were combined with 1–10 equiv of M­(ClO4)2 (M = Ni, Cu, Hg) in methanol, and the resulting solutions were monitored by UV–vis and fluorescence spectroscopy. Compound 1 showed slight effects for each metal, 2 exhibited fluorescence quenching selectively for Hg­(II), 3 showed significant changes for all cations, and 4 generally demonstrated fluorescence quenching for all cations. A discussion of the causes behind these changes is also presented.