Exploring a series of monoethynylfluorenes as alkynylating reagents for mercuric ion: Synthesis, spectroscopy, photophysics and potential use in mercury speciation

New luminescent mononuclear mercury(II) mono- and dialkynylated complexes containing substituted fluorene and fluorenone units [R–CC–HgCH3] and [R–CC–Hg–CC–R] (R = 9,9-dialkylfluorene-2-yl and fluoren-9-one-2-yl; alkyl = H, ethyl, hexyl, octyl, hexadecyl) were prepared in good yields by mercuration of terminal acetylene R–CCH with CH3HgCl and HgCl2 at room temperature via the dehydrohalogenation reaction. The structures of these organomercurial compounds were characterized by IR and NMR spectroscopies, elemental analysis and FAB mass spectrometry. Their optical and photoluminescence spectra were also studied. The structural features of one complex was elucidated by X-ray crystallography in which there is an indication of weak mercuriophicity among the molecules in the solid state. A new protocol is developed for derivatization of inorganic mercury(II) ion into dialkynyl mercury(II) compounds followed by the ready extraction into dichloromethane, which can be analyzed by HPLC technique using UV detection. These results have important implications in the development of analytical procedures for the determination of mercuric ion in aqueous solutions.

Graphical abstractThe synthesis, structural and photophysical characterization of some photoluminescent alkynyl derivatives of methylmercury and inorganic mercury functionalized with substituted fluorene moieties were reported. These metal complexes are potentially useful for the development of a new scheme for derivatization of mercuric ion to Hg(II) alkynyls for HPLC analysis.Figure optionsDownload full-size imageDownload as PowerPoint slide