Synthesis and characterization of new luminescent complexes of
osmium, rhodium and iridium. Electrochemistry, photochemistry
and photophysics of these luminescent complexes. Exploring
potential uses as light harvesting agents, photochemical and
electrochemical catalysts, and emissive DNA labels.
Developing new methodologies for undergraduate science
education.
Research
Rhodium Polypyridyl Complexes. My students and I have
developed a high yield, three step synthesis for making mixed
bidentate ligand complexes of rhodium. We compared the
microwave and conventional synthesis of the first step using a
simple procedure—a vast improvement over the current literature
procedures. We made the second intermediate, a triflate,
again developing an improved synthesis over the literature, and
demonstrated its versatility by synthesizing eighteen different
mixed ligand systems in high purity. We are extending this
synthetic method to tridentate ligands again using a triflate
intermediate. We have synthesized six new mixed tridentate
ligand complexes and are currently finishing the characterization
of these compounds.
Osmium Bipyridine Complexes. As a part of an ongoing project
on the synthesis and spectroscopic studies of osmium compounds with
interesting electrochemical and photochemical properties, my
students and I have synthesized several complexes with alkyl,
phenyl, halide, pyridine, and phosphine ligands. All of these
complexes contain the bis-(2,2'-bipyridine)-carbonyl osmium(II)
moiety and use a triflate intermediate as the starting point for
this chemistry. To date we have isolated and characterized
three sets of cis:trans isomers—methyl, ethyl, phenyl.
In order to explore the generality of the triflate intermediate and
to study electronic effects, we have developed synthetic and
purification procedures for a series of halide complexes and are
currently characterizing them. Prior to our work only the
chloride complex has been synthesized and characterized. We
are currently synthesizing a series of triflate precursors with ten
different bipyridines. Once we have completed this, we will
attach pyridine to each and characterize these as model systems for
the osmium pyridylporphyrin systems detailed below.
In order to determine the effect of substitution of phosphine
ligands on the electronic properties of the osmium moiety, we have
synthesized bis-(2,2'-bipyridine)-carbonyl-phosphine osmium(II)
complexes using eleven different substituted
triarylphosphines. Characterization of these complexes is
currently underway.
In order to determine the effect of substitution of diimine ligands
on the electronic properties of the osmium moiety, we have
synthesized bis-(diimine)-carbonyl-triphenylphosphine osmium(II)
complexes using eight different substituted bipyridine and
1,10-phenanthrolines ligand. Characterization of these
complexes is currently underway.
Osmium Complexes Linked to Porphyrins. My colleague, Dr.
Alison G. Hyslop, and I have synthesized and characterized two
osmium pyridylporphyrin complexes. These compounds are of
interest because they exhibit energy and/or electron transfer
between the porphyrin and the metal center and may be of use in
light harvesting processes such as solar energy collection and
storage panels. Building on our original osmium-porphyrin
work, my research group and I are currently preparing a series of
osmium(II) complexes with different bipyridines to attach to the
pyridylporphyrin. The goal of these experiments is to
determine the effect of electron donating and electron withdrawing
groups on the balance between energy and electron transfer.
We have synthesized nine precursors, each with a different
bipyridine, and have begun to react them with pyridylporphyrin.