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Description:
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This dissertation details the synthesis and analysis of novel supramolecular
species that feature simple fluorinated organomercurials , such as trimeric perfluoroortho -
phenylene mercury ([o -C6F4Hg]3 ) . These organomercurials can complex a variety
of unsaturated substrates including arenes and alkynes . The major emphasis was on
developing molecular architectures that are held together in part by secondary Hg -Calkyne
interactions .
Diphenylpolyynes , hydrocarbons featuring extended regions of unsaturation ,
were found to complex with [o -C6F4Hg]3 in a series of adducts . While the internal
structures of the hydrocarbons themselves were found to be basically unaltered , within
the crystals the polyynes were physically separated from one another by intervening
molecules of [o -C6F4Hg]3 , preventing them from cross -linking . This leads to a
substantial stabilizing effect , for example [o -C6F4Hg]3 and Ph (CC )4Ph form a 2 :1
adduct that is stable at temperatures up to 120 ºC above the pure hydrocarbon .
Adducts of [o -C6F4Hg]3 and molecules containing a 1 ,3 ,5 -triethynyl benzene
core display a variety of novel properties . 1 ,3 ,5 -tris (trimethylsilylethynyl ) benzene
forms binary supramolecular stacks with [o -C6F4Hg]3 . The structure also displays large
cylindrical 1 -dimensional cavities . These cavities are lined with non -polar groups , have
an internal diameter of 6 .2 Å , and remain stable in the absence of guests . The compound
readily interacts with and reversibly adsorbs simple alkanes .
1 ,3 ,5 -tris (phenylethynyl ) benzene forms similar stacks with [o -C6F4Hg]3 , albeit
without the cavities . Upon irradiation with visible and ultraviolet light , this adduct emits a long -lived emission that was hitherto unreported . From computer calculations and
lifetime measurements , it appears this radiation is the phosphorescence of the pure
hydrocarbon .
Intensive structural studies have also been performed on adducts containing
polyaromatic compounds , including phenanthrene , and the organomercurials [o -
C6F4Hg]3 , pentafluorophenyl mercury chloride and bromide . These experiments were
performed to determine if Lewis acid -p complexes could be made with monofunctional
mercury compounds . Polyaromatic hydrocarbons , such as phenanthrene and
diphenylacetylene , were used as the substrates for these investigations . While all the
mercurials formed adducts with the substrates , the photophysical measurements were not
uniform and indicate that [o -C6F4Hg]3 has a stronger heavy -atom effect because of the
cooperativity of the three mercury atoms . |