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Description:
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This dissertation focuses on the phosphorescence of organic chromophores using
perfluoro -ortho -phenylene mercury (1 ) and bis (pentafluorophenyl )mercury (2 ) as
external heavy atom effect inducers . To ascertain the suitability of these luminescent
adducts for OLED applications , several research objectives have been investigated .
To further shorten the triplet lifetimes of adducts involving 1 , a strategy was
developed which combines both internal and external heavy atom effects . Specifically ,
complexes involving 1 and N -methylcarbazole , N -methylindole and the 1 -
halonaphthalenes were investigated . The existence and stability of the complexes could
be confirmed in solution by fluorescence spectroscopy . In the solid state , these adducts
form supramolecular binary stacks where the molecules of 1 alternate with the aromatic
substrate . As a result of the mercury external heavy atom effect , all of these adducts
display intense room temperature phosphorescence of the free arene . With the Nheterocycles ,
the triplet lifetimes were drastically reduced to below 100 mu -s .
To appreciate the origin of the unusual heavy atom effects observed in arene
adducts with 1 , 2 was studied as a monofunctional analog to 1 . By utilizing fluorescence
spectroscopy , naphthalene , biphenyl , and fluorene complexes of 1 and 2 have been
detected in solution . The solid state structure of the adducts with 2 reveal
supramolecular binary stacks . Comparison of the photophysical results supports the
occurrence of cooperative effects between the Lewis acidic mercury centers of 1 , which
make it a more efficient external heavy -atom effect inducer . Polymeric materials which are amenable to deposition in thin layers were
investigated as substrates for 1 and 2 . Both poly (vinyl -2 -naphthalene ) and
poly (vinylcarbazole ) interact with 1 and 2 in solution as evidenced by fluorescence
spectroscopy . With the solid blend 1•PVK , a small doping percentage of 1 results in
white emission , while larger percentages of 1 yield bright orange emission .
This dissertation presents the first structurally characterized ternary complex with
1 , carbazole , and coordinating solvents THF and triethylamine . IR spectroscopy and
short N···O and N···N distances in the solid state indicates that the acidic N -H moiety of
carbazole interacts with the solvent by hydrogen bonding . In the extended structure ,
molecules of 1 and the hydrogen bonded complex alternate to form supramolecules . |