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. In another approach, metal-based emissions in
monomeric, oligomeric, and polymeric coordination compounds of
monovalent
coinage metals. 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.
RECENT
PUBLICATIONS-since 2003
42. Sinha, P.; Wilson, A.
K.; Omary,
M. A. “Beyond a T-Shape”, J. Am. Chem. Soc. 2005,
127,
12488-12489. PDF
41. Omary, M. A.;
Rawashdeh-Omary,
M. A.; Gonser, M. W. A.; Elbjeirami, O.; Grimes, T.; Cundari, T. R.;
Diyabalanage, H, V. K.; Palehepitiya Gamage, C. S.; Dias, H. V. R.
“Metal
Effect on the Supramolecular Structure, Photophysics, and Acid/Base
Character
of Trinuclear Pyrazolato Coinage Metal Complexes”, Inorg. Chem.
2005,
in press (Published on the Web September 10, 2005). PDF
40. Burress, C.; Elbjeirami,
O.;
Omary, M. A.; Gabba”, F. P. “Five-Order-of-Magnitude Reduction of
the
Triplet Lifetimes of N-Heterocycles by Complexation to a
Trinuclear
Mercury Complex”, J. Am. Chem. Soc. 2005, 127,
12166-12167.PDF
39. Mohamed, A. A.;
Rawashdeh-Omary, M.
A.; Omary, M. A.; Fackler, J. P., Jr. “External
heavy-atom effect of gold in a supramolecular acid-base p stack” Dalton Trans. 2005,
2597”2602.
38. Vorontsov, I. I.;
Kovalevsky, A. Yu.;
Chen, Y-S.; Graber, T.; Novozhilova, I. V.; Omary, M. A.; Coppens,
P. “Shedding
Light on the Structure of a Photo-induced Transient Excimer by
Time-resolved
Diffraction” Phys. Rev. Lett. 2005, 94,
193003/1-193003/4.
37. Dias, H. V. R.;
Diyabalanage, H. V.
K.; Eldabaja, M. G.; Elbjeirami, O.; Rawashdeh-Omary, M. A.; Omary,
M. A.
“Brightly Phosphorescent Trinuclear Copper(I) Complexes of Pyrazolates:
Substituent Effects on the Supramolecular Structure and Photophysics”, J.
Am. Chem. Soc. 2005, 127, 7489-7501.PDF
36. Omary, M. A.;
Sinha, P.;
Bagus, P.S.; Wilson, A.K. “Electronic Structure of Mercury Oligomers
and
Exciplexes: Models for Long-range/Multi-center Bonding in
Phosphorescent
Transition Metal Compounds”, J. Phys. Chem. A 2005,
109, 690-702.PDF
35. Omary, M. A.;
Mohamed, A. A.;
Rawashdeh-Omary, M. A.; Fackler, J. P., Jr. “Photophysics of
Supramolecular
Binary Stacks Consisting of Electron-rich Trinuclear Au(I) Complexes
and
Organic Electrophiles” Coord. Chem. Rev. 2005, 249,
1372-1381.
34. Elbjeirami, O.; Omary,
M. A.;
Stender, M.; Balch, A. L. “Anomalous structure-luminescence
relationship in
phosphorescent gold(I) isonitrile neutral complexes” Dalton Trans.
2004,
3173 - 3175.
33. Omary, M. A.;
Rawashdeh-Omary,
M. A.; Diyabalanage, H. V. K.; Dias, H. V. R. “Blue Phosphors of
Dinuclear and
Mononuclear Copper (I) and Silver(I) Complexes of
3,5-Bis(trifluoromethyl)pyrazolate and the Related
Bis(pyrazolyl)borate” Inorg.
Chem. 2003, 42, 8612-8614.PDF
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.PDF
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.
PDF
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.PDF
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. PDF
28. Dias, H. V. R.;
Diyabalanage, H. V.
K.; Rawashdeh-Omary, M. A.; Franzman, M. A.; Omary, M. A.
“Bright
Phosphorescence of a Trinuclear Copper (I) Complex: Luminescence
Thermochromism, Solvatochromism, and “Concentration Luminochromism”“ J.
Am.
Chem. Soc. 2003, 125, 12072-12073. Recognized
as a “Heart-Cut”
item in the November 17, 2003 issue. “Heart Cut” is an electronic
feature
journal by the American Chemical Society that highlights the most
interesting
new publications. PDF
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.PDF
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.PDF
25.
Omary, M.
A.; Kassab, R. M.; Haneline, M. R.; Elbjeirami, O.; Gabba”,
F. P.; “Enhancement
of the Phosphorescence of Organic Luminophores Upon Interaction with a
Mercury
Trifunctional Lewis Acid”, Inorg. Chem. 2003, 42,
2176-2178. PDF