1,096 research outputs found
Long-Range Surface Plasmon Polariton Active Structures Based on Optically-Pumped Dye-Doped Polymer Gain Media
No full textSolid state organic gain medium using optically-pumped dye molecules doped in a polymer host is considered as the top cladding of a long-range surface plasmon polariton (LRSPP) structure to enable active plasmonic devices with interesting applications operating in the near-infrared.The gain media is a thin film of PMMA (poly (methyl methacrylate)) doped with ~ 0.9 wt% organic dye molecules of IR-140 and is pump optically using 8 nsec laser pulses at 810 nm to enable stimulated emission by excited dye molecules to the LRSPP mode at ~ 880 nm.The gain media was modeled through rate equations for a four-level energy system, relating the small signal gain coefficient to the dye photo-physical parameters, dye concentration and pump irradiance. Distributed Bragg reflector (DBR) and distributed feedback (DFB) lasers were proposed using Bragg reflectors based on modulation of the metal stripe width, forming a stepped-in-width Bragg grating in the LRSPP waveguide. Single mode surface plasmon DFB and DBR lasers were designed at 882 nm, by applying coupled-mode theory and transfer matrix method (TMM).The IR-140 doped PMMA gain medium was experimentally characterized. The maximum available material gain was identified for various pump intensities and two possible pump polarization in the gain media using the variable stripe length (VSL) method. The maximum available material gain agreed well with the theoretical gain modeling performed previously.The DFB lasers and passive Bragg gratings were fabricated in the microfabrication laboratories at Center for Research in Photonics in University of Ottawa. Main fabrication processes included electron beam lithography to create stepped-in-width Bragg grating patterns with sharp corners and edges, with features as small as 150 nm.Passive Bragg gratings were successfully characterized by my colleague showing a clear dip in the transmittance spectra (~ 40%) at the designed Bragg wavelength 882 nm.DFB lasers were characterized and successfully demonstrated a highly narrowed (FWHM ~ 0.2 nm) single mode lasing peak at 882 nm. The mode profile from the DFBs’ output facet was captured by an infrared camera showing a tiny bright spot surrounded with dim spontaneous emission
Catalytic activity of some palladium complexes of a phosphorus ylide and structure of a 2-phenylaniline-based palladacycle complex
No full textA six-membered N,C-palladacycle bearing the 2-phenylaniline bidentate ligand (1) and three other palladium complexes of a phosphorus ylide (2, 3 and 4) were utilized in Suzuki reactions between phenylboronic acid and a number of aryl bromides and chlorides. The complexes were found to be capable homogeneous catalysts for a variety of substrates, affording the coupled products in good to excellent yields. The structure of compound I, determined by X-ray diffraction, is also reported
[1,2-Bis(diphenylphosphanyl)ethane-κ2P,P′]{2-[(4-nitrobenzoylmethyl)diphenylphosphanyl]phenyl-κ2C,C′}palladium(II) trifluoromethanesulfonate–dichloromethane–n-hexane (1/1/0.5)
No full textIn the cation of the title compound, [Pd(C26H19NO3P)(C26H24P2)]CF3O3S·CH2Cl2·0.5C6H14, the PdII atom has a slightly tetrahedrally distorted square-planar coordination geometry. The PdC3P and PdC2P2 five-membered metallacycles adopt envelope and twist conformations, respectively. In the crystal, intermolecular C—H...O hydrogen bonds link cations and anions into a three-dimensional network. The dichloromethane solvent molecule is disordered over three orientations with a site-occupancy ratio of 0.5/0.3/0.2. The n-hexane solvent molecule has a crystallographically imposed centre of symmetry
Triphenyl[(4-phenylbenzoyl)methyl]phosphonium trifluoromethanesulfonate
No full textIn the cation of the title compound, C32H26OP+·CF3O3S−, the dihedral angle between the benzene rings of the biphenyl group is 42.37 (8)°. In the crystal, the cations and anions interact through intermolecular C—H...O hydrogen bonds, forming chains parallel to the b axis. These chains are further linked by C—H...π stacking interactions into layers parallel to the bc plane
Orthopalladation of phosphorus ylides in endo position with bidentate ligands
No full textThe ortho-metallated complexes [Pd(2){kappa(2)(C,C)-C(6)H(4)(PPh(2)CHC(O)C(6)H(5)R}(2)(mu-Cl)(2)] (R = Ph (1a), NO(2) (1b), Br (1c)) were prepared by refluxing equimolar mixtures of Ph(3)P=CHC(O)C(6)H(5)R, (R = Ph, NO(2), Br) and Pd(OAc)(2) in MeOH, followed by an excess of NaCl. The dinuclear complexes (1a-1c) react with silver trifluoromethylsulfonate and bidentate ligands [L = bipy (2,2'-bipyridine), phen (phenanthroline), dppe (bis(diphenylphosphino)ethane), dppp (bis(diphenylphosphino)propane)] giving the mononuclear stabilized orthopalladated complexes in endo position [Pd{kappa(2)(C,C)-C(6)H(4)(PPh(2)CHC(O)R}L](OTf) [R = Ph, L = phen (2a), bipy (3a), dppe (4a), dppp (5a); R = NO2, L = phen (2b), bipy (3b), dppe (4b), dppp (5b); R = Br, L = phen (2c), bipy (3c), dppe (4c), dppp (5c); OTf = trifluoromethylsulfonate anion]. Orthometalation and ylidic C-coordination are demonstrated by an X-ray diffraction study of 2c and 3c. In the structures, the palladium atom shows a slightly distorted square-planar coordination geometr
Synthesis and Characterization of 2-Phenylaniline Cyclopalladated Complexes
No full textReaction of the dinuclear complex [Pd{kappa 2-N2',C1-2-(2'-NH2C6H4)C6H4}Cl](2) (1) with ligands (L = 4-picoline, sym-collidine) gave the six-membered palladacycles [Pd{kappa 2-N2',C1-2-(2'-NH2C6H4)C6H4}Cl(L)] (2). The complex 1 reacted with AgX (X = CF3SO3, BF4) and bidentate ligands [L-L = phen (phenanthroline), dppe (bis(diphenylphosphino)ethane), bipy(2,2'-bipyridine) and dppp (bis(diphenylphosphino) propane)] giving the mononuclear orthopalladated complexes [Pd{kappa 2-N2',C1-2-(2'-NH2C6H4)C6H4}(L-L)] (3) [L-L = phen, dppe, bipy and dppp]. These compounds were characterized by physicochemical methods, and the structure of [Pd{kappa 2-N2',C1-2-(2'-NH2C6H4)C6H4}Cl(L)] (L = sym-collidine) was determined by single-crystal X-ray analysis
Synthesis and application of orthopalladated complex of 4-phenylbenzoylmethylenetriphenylphosphorane as a high active catalyst in the Suzuki cross-coupling reactio
No full textThe ortho-metallated complex [Pd(mu-Cl){kappa(2)(C,C)-[C6H4(PPh2CHC(O)C6H4-Ph-4)}](2) (2a) was prepared by refluxing of Pd(OAc)(2) and ((Ph)(3)PCHCOC6H4-Ph-4) (PhBPPY) of in CH2Cl2 followed by addition of an excess of KCl in MeOH Complex (2a) reacts with triphenylphosphine to give the mononuclear derivative [Pd(Cl)(PhC6H4COCHPPh2C6H4)(PPh3)] (3a) whose crystal structure has been determined by single crystal X-ray diffraction. The Suzuki reactions of aryl bromides and chlorides of varying electron density using complex (3a) as an efficient catalyst were performed, giving the cross-coupling products in good to excellent yields
Correction to: Destructive Roles of Fibroblast-Like Synoviocytes in Chronic Inflammation and Joint Damage in Rheumatoid Arthritis (Inflammation, (2021), 44, 2, (466-479), 10.1007/s10753-020-01371-1)
No full textFollowing the publication of the original article, the corresponding author noticed that the second corresponding author has not been mentioned. The below statement must be added to the correspondence section: Jafar Karami; Department of Immunology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. E-mail: [email protected]; [email protected] The original article has been corrected. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
Synthesis and structural studies of cyclopalladated complexes of secondary benzylamines
No full textDi-nuclear cyclopalladated acetato-bridged complexes derived from secondary benzylamines, [Pd2{(C,N)-C6H4CH2NH(R)}2(μ-OAc)2] (R = Et (1), R = t-Bu (2)) were obtained by refluxing of corresponding benzylamines and Pd(OAc)2 in a 1:1 M ratio. Complex 1 was also prepared by heating the bis-amine complex [Pd(OAc)2(PhCH2NH(Et))2] (3) in toluene at 60 °C. Complex 3 reacted with an excess of NaCl to give [Pd(Cl)2(PhCH2NH(Et))2] (4). Metathetical reaction of 1 and 2 with an excess of NaCl or NaBr afforded the corresponding dimers [Pd2{(C,N)-C6H4CH2NH(R)}2(μ-X)2] (X = Cl, R = Et (5); X = Cl, R = t-Bu (6); X = Br, R = t-Bu (7)). The cationic complex [Pd(C,N)-C6H4CH2NH(Et)(phen)]BF4 (8) can be obtained by reacting chloro bridge dimer 5 with AgBF4 and 1,10-phenanthroline (phen). Neutral ligands split the halide bridges in 6 and 7 to give monomeric complexes [Pd(C,N)-C6H4CH2NH(t-Bu)X(L)] (X = Cl, L = PPh3 (9); X = Br, L = Me3Py (10)). Complexes 1–10 were fully characterized by elemental analysis, IR and NMR spectroscopies. In addition, the crystal structures of 2, 3, 4, 8, 9 and 10 were determined by single-crystal X-ray diffraction analysis. In all these structures, the palladium atom shows a distorted or slightly distorted square-planar geometry
New structure for adder with improved speed, area and power
No full textAdders are the main parts of processing circuits and play an important role in all mathematical operations like subtraction, multiplication, division, etc. Carry Look ahead Adder (CLA) is one of the fastest adder structures that is widely used in the processing circuits. In this article a new structure for adder is proposed. The results show that compared to the previous common Modified Carry Look ahead Adder (MCLA) structure, the proposed structure has very smaller on-chip area and delay and also it has lower power consumption. Using the proposed structure a 64-bit adder is designed and results are presented. The circuit is designed in TSMC 0.18μm CMOS technology with 1.8v power supply and simulated with HSPICE.Fatemeh Karami H. and Ali K. Horestan
- …
