Mohammad Esteghamatian

Bio: Mohammad Esteghamatian is an academic researcher from Xerox. The author has contributed to research in topics: Electroluminescence & Tetrahedral molecular geometry. The author has an hindex of 4, co-authored 4 publications receiving 556 citations.

Synthesis, Structure, and Electroluminescence of BR2q (R = Et, Ph, 2-Naphthyl and q = 8-Hydroxyquinolato)

Abstract: Three 8-hydroxyquinolato (q) boron compounds B(C2H5)2q (1), BPh2q (2), and B(2-naph)2q (3) have been synthesized by the reaction of 8-hydroxyquinoline with an appropriate BR3 compound. Compounds 1−3 have a tetrahedral geometry as demonstrated by the structure of 1 determined by a single-crystal X-ray diffraction analysis. Compounds 1−3 emit a green-blue color at λmax = 495−500 nm when irradiated by UV light. The electroluminescent (EL) properties of 2 and 3 were examined by fabricating EL devices using 2 and 3 as the light-emitting layer, respectively. The devices of 2 produce a yellow-green light with broad emission spectra, attributed to the formation of an exciplex of 2 with the N,N‘-di-1-naphthyl-N,N‘-diphenylbenzidine (NPB) in the hole transport layer while the intrinsic EL emission of compound 3 was observed. Both 2 and 3 were found to be good electron transport materials in EL devices.

Isomerism and Blue Electroluminescence of a Novel Organoboron Compound: BIII2(O)(7‐azain)2Ph2

Abstract: Bright blue light with a maximum at 450 nm is emitted by both structural isomers of the novel, stable BIII2 (O)(7-azain)2 Ph2 (7-azain=7-azaindole anion) on irradiation with UV light. The isomer shown in the picture has approximate C2 symmetry (the other isomer approximate Cs symmetry) and electroluminesces when used as the emitting layer in an electroluminescent device.

Isomerie und blaue Elektrolumineszenz einer neuartigen Organoborverbindung: BIII2(O)(7‐azain)2Ph2

Abstract: Helles blaues Licht mit einem Maximum bei 450 nm emittieren die beiden Strukturisomere des neuartigen, stabilen BIII2(O)(7-azain)2Ph2 (7-azain = 7-Azaindol-Anion) beim Bestrahlen mit UV-Licht. Das im Bild gezeigte Isomer ist nahezu C2-symmetrisch (das nicht gezeigte andere Isomer etwa Cs-symmetrisch) und elektroluminesziert auch, wenn es als emittierende Schicht in einem Elektrolumineszenz-Bauelement verwendet wird.

Advances in the Synthesis of Organoborane Polymers for Optical, Electronic, and Sensory Applications

Abstract: The past decade has witnessed renewed interest and numerous unexpected discoveries in the area of main group organometallic chemistry. Unusual bonding modes have been uncovered,1-4 new materials have been developed,5,6 and new applications are being pursued.7-12 With respect to new materials with unusual properties, an exciting field is the development of hybrid polymers that combine main group elements with typical organic structures in one framework.13,14 Among main group organic-inorganic hybrid polymers, those involving Group 14 and Group 15 elements have received tremendous attention over the past several decades, with silicones, polysilanes, and polyphosphazenes among the most thoroughly studied materials.15-17 A variety of other classes of new polymers containing not only silicon and phosphorus,18-22 but also the heavier homologues, such as germanium, tin, arsenic, and antimony have been introduced more recently.23-26

Efficient blue emission from siloles

Abstract: 2,3,4,5-Tetraphenylsiloles with different 1,1-substituents on the ring silicon atoms, i.e., 1,1-dimethyl-2,3,4,5-tetraphenylsilole (1), 1-methyl-1-(3-chloropropyl)-2,3,4,5-tetraphenylsilole (2), 1-methyl-1,2,3,4,5-pentaphenylsilole (3) and hexaphenylsilole (4), are synthesized and characterized. While all the siloles emit intense blue light readily observable by naked eyes under normal room illumination conditions, the film of their acyclic cousin without silicon, namely 1,2,3,4-tetraphenylbutadiene (5), does not fluoresce, revealing the vital role of the planar and rigid silacyclopentadiene ring in the solid-state photoluminescence process. The electronic transitions of the siloles can be tuned by varying the 1,1-substituents, and the inductive and conjugating effects of the aromatic rings confer low LUMO energy levels and high emission efficiencies on the phenyl-substituted siloles. The electroluminescence device of the 1-phenylsilole 3 shows a high brightness (4538 cd m−2 at 18 V) and an excellent external quantum efficiency (0.65% at 17 V and 94 mA cm−2).

Impact of donor-acceptor geometry and metal chelation on photophysical properties and applications of triarylboranes.

Abstract: Three-coordinate organoboron compounds have recently found a wide range of applications in materials chemistry as nonlinear optical materials, chemical sensors, and emitters for organic light-emitting diodes (OLEDs). These compounds are excellent electron acceptors due to the empty pπ orbital on the boron center. When accompanied by electron donors such as amines, these molecules possess large electronic dipoles, which promote donor−acceptor charge-transfer upon excitation with light. Because of this, donor−acceptor triarylboranes are often highly luminescent both in the solid state and in solution. In this Account, we describe our research to develop donor−acceptor triarylboranes as efficient blue emitters for OLEDs. Through the use of hole-transporting donor groups such as 1-napthylphenylamines, we have prepared multifunctional triarylboranes that can act as the emissive, electron transport, or hole transport layers in OLEDs. We have also examined donor−acceptor compounds based on 2,2′-dipyridylamine or...

Luminescent materials: locking π-conjugated and heterocyclic ligands with boron(III).

Abstract: Multidisciplinary research on novel organic luminescent dyes is propelled by potential applications in plastic electronics and biomedical sciences. The construction of sophisticated fluorescent dyes around a tetrahedral boron(III) center is a particular approach that has fueled the creativity of chemists. Success in this enterprise has been readily achieved with simple synthetic protocols, the products of which display unusual spectroscopic behavior. This account is a critical review of recent advances in the field of boron(III) complexes (excluding BODIPYs and acetylacetonate boron complexes) involving species displaying similar coordination features, and we outline their potential development in several disciplines.