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 2005
60.
Omary, M. A.; Elbjeirami, O.; Palehepitiya
Gamage, C. S.; Sherman, K.; Dias, H. V. R. "Phosphorescence
Enhancement of Naphthalene-Sandwiched Trinuclear Silver(I) Complexes of
3,5-Bis(trifluoromethyl)pyrazolate", Inorg. Chem. 2009, 47, in press: DOI: 10.1021/ic8021326.PDF
59.
Yang, C.; Wang, X.; Omary, M. A. "Crystallographic observation of the dynamic gas
adsorption sites and thermal expansion in a breathable fluorous metal-organic
framework", Angew. Chem. 2009, in press: DOI: 10.1002/anie.200804739: (JOURNAL COVER). PDF
58.
Rabaa, H.; Cundari, T. R.; Omary, M. A. "Combined Tight Binding/DFT Investigation of
the Electronic Structure of Triimine-Platinum(II)/TCNQ Extended Stacks: Theoretical
Prediction of Metallic Behavior", Can. J. Chem. (special issue)
2008, in
press: DOI: 10.1139/V08-175. INVITED ARTICLE. PDF
57.
Elbjeirami, O.; Gonser, M. W. A.; Stewart, B. N.; Bruce, A. E.; Bruce,
M. R. M.; Cundari, T. R.; Omary, M. A. "Luminescence,
Structural, and Bonding Trends upon Varying the Halogen in Isostructural
Aurophilic Dimers", Dalton Trans. 2008, in press: DOI: 10.1039/b81385c; (JOURNAL COVER). PDF
56.
Quevedo-Lopez, M. A.; Alshareef, H. N.; Jia, H.; Bhansali, U.; Avendano, A.; Gnade,
B. E.; Omary, M. A. "Organic Light
Emitting Diodes for Flexible Electronics", Future FAB 2008,
26, 30-36. PDF
55.
Tekarli, S. M.; Cundari, T. R.; Omary,
M. A. "Rational Design of Macrometallocyclic Trinuclear Complexes with
54.
Taylor, T. J.; Elbjeirami, O.; Burress, C. N.; Tsunoda, M.; Bodine, M. I.; Omary, M. A.; Gabbai, F. P. "Complexation
of tolane by fluorinated organomercurials - Structures and luminescence
properties of an unusual class of supramolecular p-coordination
polymers", J. Inorg. Organomet. Polym. 2008, 18, 175-179. PDF
53.
Yang, C.; Wang, X.; Omary, M. A. "Fluorous
Metal-Organic Frameworks for High-Density Gas Adsorption", J. Am. Chem. Soc. 2007,
129, 15454-15455. PDF HIGHLIGHTED IN: a) Angew. Chem. Int. Ed.
2008, 47, 8164-8164. b) THE E-JOURNAL "ENTREPRENEUR"; SEE: http://www.entrepreneur.com/tradejournals/article/177363186.html
52.
Elbjeirami, O.; Omary, M. A.
“Photochemistry of Neutral Isonitrile Gold(I) Complexes: Modulation of
Photoreactivity by Aurophilicity and p-Acceptance Ability”, J. Am. Chem. Soc. 2007, available online. PDF
51.
Arvapally, R. K.; Sinha, P.; Hettiarachchi, S. R.; Coker, N. L.; Bedel, C. E.;
Patterson, H. H.; Elder, R. C.; Wilson, A. K.; Omary, M. A. “Photophysics of Bis(thiocyanato)gold(I)
Complexes: Intriguing Structure-Luminescence Relationships”, J. Phys.
Chem. C 2007,
111, 10689-10699. PDF
50.
Elbjeirami, O.; Burress, C. N.; Gabbaï, F. P.; Omary, M. A. “Simultaneous External and Internal Heavy-Atom
Effects in Binary Adducts of 1-Halonaphthalenes with Trinuclear Perfluoro-ortho-phenylene Mercury(II): A
Structural and Photophysical Study”, J. Phys. Chem. C 2007,
111, 9522-9529. PDF
49.
Omary, M. A.; Colis, J. C.
F.; Larochelle, C. L.; Patterson, H. H. “Optical Memory and Multi-step
Luminescence Thermochromism in Single Crystals of K2Na[Ag(CN)2]3”, Inorg. Chem. 2007, 46, 3798-3800. PDF
48.
Elbjeirami, O.; Yockel, S.; Campana, C. F.; Wilson, A. K.; Omary, M. A. “Photophysics and Bonding in Neutral Gold(I)
Organometallic Complexes with an Extended Aurophilic Supramolecular Structure”, Organometallics 2007, 26, 2550-2560. PDF
47.
Burress, C. N.; Bodine, M. I.; Elbjeirami, O.; Reibenspies, J. H.; Omary, M. A.; Gabbaï, F. P.
“Enhancement of External Spin-Orbit Coupling Effects Caused by Metal-Metal
Cooperativity”, Inorg. Chem. 2007, 46, 1388-1395. PDF
46.
Yang, C.; Messerschmidt, M.; Coppens, C.; Omary,
M. A. “Trinuclear Gold(I) Triazolates: A New Class of Wide-Band Phosphors
and Sensors”, Inorg. Chem. 2006, 45, 6592-6594. PDF
45.
Barakat, K. A.; Cundari, T. R.; Rabaâ, H.; Omary, M. A. “Disproportionation
of Gold(II) Complexes. A Density Functional Study of Ligand and Solvent
Effects”, J. Phys. Chem. B 2006, 110, 14645-14651. PDF
44.
Grimes, T.; Omary, M. A.; Dias, H. V. R.; Cundari, T. R. “Intertrimer
and Intratrimer Metallophilic and Excimeric Bonding in the Ground and
Phosphorescent Excited States of Trinuclear Coinage Metal Pyrazolates: A
Computational Study”, J. Phys. Chem. A 2006, 110, 5823-5830. PDF
43.
Chen, W. –H.; Reinheimer, E. W.; Dunbar, K. R.; Omary, M. A. “Coarse- and Fine-Tuning the Electronic Energies of
Triimine Platinum (II) Square Planar Complexes”, Inorg. Chem. 2006, 45, 2770-2772. PDF
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, 44, 8200-8210. PDF JOURNAL
COVER; URL: http://pubs.acs.org/action/showLargeCover?issue=40364397
40.
Burress, C.; Elbjeirami, O.; Omary, M. A.; Gabbaï, 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.