Research topics being pursued by the Omary group:
The Omary group is pursuing research into optoelectronic applications of luminescent materials. State-of-the-art spectroscopic instruments are being used for these studies such as: modern luminescence systems for steady-state and time-resolved measurements, tunable laser sources, molecular UV-VIS-NIR absorption and diffuse reflectance spectrophotometers, resonance Raman systems, and optical cryostats for temperature-dependent measurements down to liquid helium temperature (4.2 K) for solids and solutions. Modern DFT and ab initio computations are also being used to further characterize the electronic structure of the materials studied. Several classes of compounds are being synthesized and studied, including:
• Phosphorescent materials for
light-emitting
display devices (LEDs):
We are designing synthetic strategies to
enhance the
phosphorescence of organic and inorganic luminophores. In one
approach,
conventional organic fluorophores are made to exhibit room-temperature
phosphorescence in the solid state owing to either an external or
internal heavy atom effect in systematically designed systems that
contain d10 metals (e.g., see papers 25 and 33 below).
In another approach, metal-based emissions in monomeric, oligomeric,
and polymeric coordination
compounds of monovalent coinage metals (e.g., see papers 28-30, and 32
below). The
enhancement of phosphorescence should lead to LEDs with stronger
electroluminescence quantum efficiency (QE), as the maximum theoretical
internal
QE is usually 25% for fluorescent LEDs while it can be up to 100% for
phosphorescent LEDs.
• Charge-Transfer Complexes as Solar
Cell Dyes:
We have been synthesizing "black absorbers"
that are capable of absorbing strongly across the visible region and
into the
near infrared (NIR) region. One useful class consists of
(diimine)(dithiolate) compounds of
d8 transition metals (PtII,
PdII, and NiII) with
anchoring groups (e.g., carboxylate or phosphonate) attached to the
diimine in
order to allow their adsorption on the surface of a wide band gap
semiconductors such as TiO2 or SnO2. The band gap
of such
semiconductors is in the UV region, too high to overlap with the
desired solar
spectral range, but attaching dyes of charge transfer complexes to the
surface
of the semiconductor results in efficient absorption of the solar
radiation. A second class involves donor-acceptor
neutral and ionic compounds in which the donor is a d8 complex and the acceptor is an organic compound such as various
TCNX nitriles and poly(nitro)-9-fluorenones. These binary
materials absorb strongly
across the visible and into a significant portion of the NIR region and
we have
discovered that there is no need to have conventional anchoring groups
in such
complexes (e.g., see paper 26 below).
RECENT
PUBLICATIONS-since 2002
33.
Omary, M. A.; Rawashdeh-Omary,
M. A.; Diyabalanage, H. V. K.; Dias,
H. V. R. “Blue Phosphors of Dinculear and Mononuclear Copper (I) and
Silver(I)
Complexes with Fluorinated Pyrazolate Ligands” Inorg.
Chem. 2003, 42, 8612-8614.
32.
Hettiarachchi, S. R.; Patterson, H. H.; Omary, M. A. “"Write/Read/Erase"
with Laser Irradiation of Dicyanoargentate(I) Doped and Pure Crystals”
J.
Phys. Chem. B 2003, 107,
14249-14254.
31.
Dunbar, K. R.; Schelter, E. J.; Palii, A. V.;
Ostrovsky, S. M.; Mirovitskii, V. Y.; Hudson, J. M.; Omary, M. A.;
Klokishner, S. I.; Tsukerblat, B. S. “Unusual Magnetic Behavior of
Six-Coordinate,
Mixed-Ligand Re(II) Complexes: Origin of a Strong Temperature
Independent
Paramagnetism” J.
Phys. Chem. A 2003, 107, 11102-11111.
30.
Barakat, K. A.; Cundari, T. R.; Omary,
M. A. “Jahn-Teller Distortion in
the Phosphorescent Excited State
of Three-coordinate Au(I) Phosphine Complexes” J. Am. Chem.
Soc. 2003, 125,
14228-14229.
29. White-Morris,
R. L.; Olmstead, M. M.; Balch, A. L.; Elbjeirami, O.; Omary, M. A. “Orange
Luminescence and Structural Properties of Three Isostructural
Halocyclohexylisonitrilegold(I) Complexes”, Inorg.
Chem. 2003, 42, 6741-6748.
28. Dias,
H. V. R.; Diyabalanage, H. V. K.; Rawashdeh-Omary, M. A.; Franzman, M.
A.; Omary,
M. A. “Bright, Tunable Phosphorescence of a Trinuclear Copper (I)
Complex:
Luminescence Thermochromism, Solvatochromism, and Self-Tuning” J. Am. Chem.
Soc. 2003,
125, 12072-12073.
27. Maspero,
A.; Kani, I.;
Mohamed, A. A.; Omary, M. A.; Staples, R. J.; Fackler, J. P.,
Jr.
"Syntheses and Structures of Dinuclear Gold(I) Dithiophosphonate
Complexes
and the Reaction of the Dithiophosphonate Complexes with Phosphines:
Diverse
Coordination Types",
Inorg.
Chem. 2003, 42, 5311-5319.
26. Smucker, B.
W.; Hudson,
J. M.; Omary, M. A.; Dunbar, K. R. “Structural, Magnetic, and
Optoelectronic Properties of Diimine-dithiolato Pt(II) and Pd(II)
Complexes and
their Charge-Transfer Adducts with Nitrile Acceptors”, Inorg.
Chem. 2003, 42,
4714-4723.
25. Omary,
M. A.; Kassab,
R. M.; Haneline, M. R.; Elbjeirami, O.; Gabbaï, F. P.;
“Enhancement of
the Phosphorescence of Organic Luminophores Upon Interaction with a
Mercury
Trifunctional Lewis Acid”, Inorg.
Chem. 2003, 42,
2176-2178.
26. Smucker, B.
W.; Hudson,
J. M.; Omary, M. A.; Dunbar, K. R. “Structural, Magnetic, and
Optoelectronic
Properties of Diimine-dithiolato Pt(II) and Pd(II) Complexes and their
Charge-Transfer Adducts with Nitrile Acceptors”, Inorg.
Chem. 2003, 42, 4714-4723.
25. Omary, M. A.; Kassab,
R.
M.; Haneline, M. R.; Elbjeirami, O.; Gabbaï, F. P.;
“Enhancement of the
Phosphorescence of Organic Luminophores Upon Interaction with a Mercury
Trifunctional Lewis Acid”, Inorg.
Chem. 2003, 42,
2176-2178.
24. Assefa, Z.;
Omary,
M. A.; McBurnett, B. G.; Mohamed, A. A.; Patterson, H. H.;
Staples,
R. J.; Fackler, J. P., Jr. "Syntheses, Structure and Photoluminescence
Properties of the 1-Dimensional Chain Compounds [(TPA)2Au][Au(CN)2]
and (TPA)AuCl (TPA = 1,3,5-Triaza-7-phosphaadamantane)" Inorg. Chem.2002,
41, 6274-6280.
23.
Hettiarachchi, S. R.;
Rawashdeh, M. A. -O.; Kanan, S. M.; Omary, M. A.; Patterson, H.
H.;
Tripp, C. P. “Spectroscopic Studies on “Exciplex Tuning” for
Dicyanoaurate(I)
Ions Doped in Potassium Chloride Crystals”
J. Phys.
Chem. B. 2002,
106, 10058-10064.
22. Fischer,
P.; Lucas, B.;
Omary, M. A.; Larochelle, C. L.; Patterson, H. H. “Reversible
Luminescence Thermochromism in Dipotassiumsodium
Tris[dicyanoargentate(I)] and
the Role of Structural Phase Transitions”
J.
Solid State
Chem.2002, 168, 267–274.
21. Kani, I.; Omary,
M.
A.; Rawashdeh, M. A. -O.; Lopez-Castillo, Z.; Flores, R.; Akgerman,
A.;
Fackler, J. P., Jr. “Homogeneous catalysis in supercritical carbon
dioxide with
rhodium catalysts tethering fluoroacrylate polymer ligands”, Tetrahedron
2002,
58, 3923-3928.
20. Rawashdeh,
M. A. -O.; Omary,
M. A.; Fackler, J. P., Jr. "Argento-aurophilic Bonding in
Organosulfur
Complexes. The Molecular and Electronic Structures of the
Heterobimetallic Complex AgAu(MTP)2" Inorg.
Chim. Acta
(special issue) 2002, 334, 376-384.
19. Burini, A.; Fackler, J. P., Jr.; Galassi, R.; Macchioni, A.; Omary, M. A.; Rawashdeh, M. A. -O.; Pietroni, B. R.; Sabatini, S.; Zuccaccia, C. “19F, 1H-HOESY and PGSE NMR Studies of Neutral Trinuclear Complexes of AuI and HgII: Evidence for Acid-Base Stacking in Solution”, J. Am. Chem. Soc. 2002, 124, 4570-4571.
This page is
maintained by
Mohammad Omary
Last updated April 8, 2004