Structure and electronic properties for a newly synthesized red fluorescent material

The ground-state structure and electronic properties of a newly synthesized red fluorescent material, 2-[3-(2-{4-[(2-hydroxy-ethyl)-methyl-amino]-phenyl}-vinyl)-5, 5-dimethyl-cyclohex-2-enylidene]-malononitrile (A31), are investigated using a hybrid density-functional theory (DFT) approach, B3LYP, and the 6-31G* basis set. We have obtained four geometrical isomers. The theoretical infrared (IR) spectrum calculated by B3LYP/6-31G* level of theory is in very good agreement with our experimental measurement. The cation and anion are optimized to clarify the effects of the hole and electron injections and the energies needed by injections are estimated.     

Vibrational spectra and structure of some oxalic acid/substituted pyridine (methyl-, amino-, and dihalogeno-) complexes: Hydrogen bond features

The Raman and infrared spectra of some polycrystalline substituted pyridine/oxalic acid complexes have been investigated and assignments in terms of group frequencies are given. Various hydrogen bonds (NH?O, OH?O, OH?N) are distinguished and crystal structures are proposed. For the stronger bases (methyl- or aminopyridines with pk_a ≈ 6) proton transfer occurs. The 1/1 complex contains infinite chains of hydrogen oxalate ions linked by strong OH?O hydrogen bonds with vOH between 2000 and 800 cm⁻¹. R_OH?O distances are 2.47–2.62 Å). The substituted pyridinium cations are linked to the chain backbone by medium NH?O hydrogen bonds with NH?O lengths of 2.71–2.81 Å. The 3,5-dichloropyridine forms a 2/1 adduct without proton transfer, in accordance with its pk_a (0.6), and strong OH?N hydrogen bonds occur (vOH about 2000 cm⁻¹ and ). Finally, the 2,6-dihalogenopyridine derivatives do not form complex with oxalic acid, presumably because of steric hindrance.     

Earth Alkaline Tetrathiosquarates: Syntheses and Crystal Structures of MgC4S4 · 6 H2O and CaC4S4 · 4 H2O

Concentrated aqueous solutions of magnesium chloride and calcium nitrate, respectively, allow on addition of the potassium salt of tetrathiosquarate, K₂C₄S₄ · H₂O, the isolation of the earth alkaline salts MgC₄S₄ · 6 H₂O ( 1 ) and CaC₄S₄ · 4 H₂O ( 2 ) as orange and red crystals. The crystal structure determinations ( 1 : monoclinic, C2/c, a = 17.2280(7), b = 5.9185(2), c = 13.1480(4) Å, β = 104.730(3)°, Z = 4; 2 : monoclinic, P2₁/m, a = 7.8515(3), b = 12.7705(5), c = 10.6010(4) Å, β = 93.228(2)°, Z = 4) show the presence of C₄S₄^2? ions with almost undistorted D_4h symmetry having average C–C and C–S bond lengths of 1.451Å and 1.659Å for 1 and 1.451Å and 1.655Å for 2 . The structure of 1 contains discrete, octahedral [Mg(H₂O)₆]²⁺ complexes. Several O–H····O and O–H····S bridges with H····O and H····S distances of less than 2.50Å connect cations and anions. The structure of 2 is built of concatenated, edge‐sharing Ca(H₂O)₆S₂ polyhedra. The Ca²⁺ ions have the coordination number eight, C₄S₄^2? act as a chelating ligands towards Ca²⁺ with Ca–S distances of 3.14Å. The infrared and Raman spectra show bands typical for the molecular building units of the two compounds.     

Spektroskopische Eigenschaften von Di(phthalocyaninato)metallaten(III) der Seltenen Erden Teil 1: Elektronische Absorptionsspektren und Schwingungsspektren

Spectroscopical Properties of Di(phthalocyaninato)metalates(III) of the Rare Earth Elements. Part 1: Electronic Absorption and Vibrational Spectra Di(phthalocyaninato)metalates(III) of the rare earth elements were prepared by the reaction of partially dehydrated lanthanide acetate with molten phthalodinitrile in the presence of potassium methylate and isolated as complex salts with different tetraalkylammonium cations, especially tetra(n-butyl)- and tri(n-dodecyl)n-octylammonium and di((triphenyl)phosphine)-iminium (abbrev.: (ⁿBu₄N), TDOA, PNP). Besides the typical strong π-π* transitions in the B, Q, N regions of the Pc^2? ligands low intensity bands at ca. 10, 11 and 19 kK are observed in the UV-Vis-NIR spectra and assigned to singulet–triplet transitions. In going from La to Lu the B band splits continously due to excitonic coupling extending from 0,71 (La) to 1,92 kK (Lu). The FIR-MIR and resonance Raman spectra are nearly metal independent with the exception of some hypsochromically shifted bands due to C? C and C? N stretching and deformation vibrations of the inner (CN)₈ ring. Only the FIR band at 157 cm^?1 (La) assigned to the asym. Ln? N stretching vibration is shifted to lower energy.     

Multi spectroscopic and computational investigations on the electronic structure of oxyclozanide

The present work contributes to a combined theoretical and experimental investigation on oxyclozanide. The experimental vibrational spectra were characterized by Fourier transform infrared (4000-400 cm^?1), Fourier transform Raman (4000-400 cm^?1), ¹H and ¹³C NMR were recorded in Deuterated methanol, UV–Vis (200–400 nm) techniques and theoretical optimized molecular geometry, harmonic vibrational spectra, magnetic spectra, and electronic spectra was calculated by Density Functional Theory (DFT) employed with B3LYP/6-311++G(d,p) basis set and compared with experimental data. The highest occupied molecular orbital - lowest unoccupied molecular orbital (HOMO-LUMO) energy was also calculated for the titled compound. The intermolecular interactions have been addressed through Hirshfeld surface analysis. In addition, Natural bond orbital (NBO) analyses of the title compound were performed to evaluate the suitable reactivity site and chemical stabilization behavior, Mulliken atomic charge distribution, and molecular electrostatic potential energy surfaces, were calculated to get a better insight into the structure of oxyclozanide. The experimental and theoretical findings suggest an excellent correlation to confirm the structure of oxyclozanide.     

Structural and vibrational investigation of para-nitraminopyridine N-oxide. A combined experimental and theoretical studies

The X-ray and vibrational spectroscopic analysis of para-nitraminopyridine N-oxide are reported. The crystals of investigated compound belong to P2(1) of the monoclinic system, Z=4, a=3.735 A, b=11.767 A, c=14.679 A and beta=93.27 degrees . Room temperature powder infrared and Raman spectra of the title compound and its deuterated analogue were measured. The molecular structure of p-nitraminopyridine N-oxide has been calculated with the aid of density functional (B3LYP) method with the extended 6-311++G(d,p) basis set. The calculated geometrical parameters of investigated molecule in gas phase were compared with experimental X-ray data. The harmonic frequencies, potential energy distribution (PED) and IR intensities of p-nitroaminopyridine N-oxide and its deuterated analogue were calculated with B3LYP method. The assignment of the experimental spectra has been made on the basis of the calculated PED. The time depend Hartree-Fock (TDHF) method was used for calculations of hyperpolarizability beta coefficient.     

Schwingungsspektroskopische Untersuchungen an Trimethylphosphonium-Kationen (CH3)3PX+ (X = H,D) und Kristallstrukturen von (CH3)3PD+SbCl6− und (CH3)3PCl+SbCl6−

Vibrational Spectra of Trimethylphosphonium Cations (CH₃)₃PX⁺ (X = H, D) and Crystal Structures of (CH₃)₃PD⁺SbCl₆^? and (CH₃)₃PCl⁺SbCl₆^? The trimethylphosphonium salts (CH₃)₃PX⁺SbCl₆^? (X = H, D) and (CH₃)₃PH⁺MF₆^? (M = As, Sb) are prepared and characterized by vibrational and NMR spectroscopy (¹H, ³¹P, ¹³C). In addition the crystal structures of (CH₃)₃PD⁺SbCl₆^? and (CH₃)₃PCl⁺SbCl₆^? are reported. (CH₃)₃PD⁺SbCl₆^? crystallizes in the orthorhombic space group Pnma with a = 1555(1) pm, b = 753.1(8) pm, c = 1166(1) pm Z = 4. (CH₃)₃PCl⁺SbCl₆^? crystallizes triclinic in the space group P1 with a = 704.6(4) pm, b = 729.5(3) pm, c = 1391.1(7) pm, α = 89.57(4)°, b? = 88.04(4)°, γ = 74.98(4)° and Z = 2.     

Darstellung,Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalyse der bindungsisomeren Chlororhodanoiridate(III) trans-[IrCl2(SCN)4]3− und trans-[IrCl2(NCS)(SCN)3]3−

Preparation, Crystal Structures, Vibrational Spectra, and Normal Coordinate Analysis of the Linkage Isomeric Chlororhodanoiridates(III) trans-[IrCl₂(SCN)₄]^3? and trans-[IrCl₂(NCS)(SCN)₃]^3? By treatment of Na₂[IrCl₆] with NaSCN in 2N HCl the linkage isomers trans-[IrCl₂(SCN)₄]^3? and trans-[IrCl₂(NCS)(SCN)₃]^3? are formed which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. X-ray structure determinations on single crystals of trans-(n-Bu₄N)₃[IrCl₂(SCN)₄] ( 1 ) (monoclinic, space group P2₁/a, a = 18.009(4), b = 15.176(3), c = 23.451(4) Å, β = 93.97(2)°, Z = 4) and trans-(Me₄N)₃[IrCl₂(NCS)(SCN)₃] ( 2 ) (monoclinic, space group P2₁/a, a = 17.146(5), b = 9.583(5), c = 18.516(5) Å, β = 109.227(5)°, Z = 4) reveal the complete ordering of the complex anions. The via S or N coordinated thiocyanate groups are bonded with Ir? S? C angles of 105.7–109.7° and the Ir? N? C angle of 171.4°. The torsion angles Cl? Ir? S? C and N? Ir? S? C are 3.6–53.0°. The IR and Raman spectra of ( 1 ) are assigned by normal coordinate analysis using the molecular parameters of the X-ray determination. The valence force constants are f_d(IrS) = 1.52 and f_d(IrCl) = 1.72 mdyn/Å.     

Reaction of bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) with PhCCo3(CO)9: synthesis and X-ray characterization of the dmpdmh-bridged polymorphs of PhCCo3(CO)7[(MeO)2PN(Me)N(Me)P(OMe)2]

The tricobalt cluster PhCCo₃(CO)₉ reacts with the bis(phosphanyl)hydrazine ligand bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) to give the monosubstituted cluster [PhCCo₃(CO)₈]₂(dmpdmh) and the disubstituted cluster PhCCo₃(CO)₇(dmpdmh) as the major products. This latter cluster contains a bridging dmpdmh ligand. Both IR and NMR spectroscopies (³¹P and ¹H) have been employed in the solution characterization of these two clusters. The solid-state structure of PhCCo₃(CO)₇(dmpdmh) was unequivocally established by X-ray diffraction analysis, which has revealed the presence of two different polymorphs for this particular cluster. The first polymorph crystallizes in the monoclinic space group P2₁/n, a = 9.7127(7) Å, b = 17.025(2) Å,c = 16.894(1) Å, = 96.245(5)°, V = 2777.0(4) ų, Z = 4, and d _calc = 1.689 g/cm³; while the second polymorph crystallizes in the orthorhombic space group Pbca, a = 16.925(2) Å, b = 16.208(2) Å, c = 20.541(3) Å, V = 5635(1) ų, Z = 8, and d _calc = 1.665 g/cm³.     

Experimental and numerical studies of weak blast waves in air

Effects of viscosity and vibrational nonequilibrium on the profile of a weak, spherical N-wave in air are experimentally and numerically studied. Weak blast waves were generated, in a quiescent air dome, by spark discharges and exploding wires and observed by high frequency response microphones over 40 meters. Some similarity relationships were obtained from the blast wave experiments. For observed N-waves having less than 100 Pa peak overpressure, the peak overpressure p _f and the duration of the positive phaset _d+ are found to vary with the radial distance from the sourcer as p _f r ^–1.38 andt _d + r ^0.19, whilst the rise time of the blast wave t _f linearly increases with distance. Similar trends were also found for the negative phase of the blast wave. Numerical simulations were carried out to compare with the blast wave data. The Navier-Stokes equations for spherical symmetric flows were solved by coupling with a relaxation equation for vibrational excitation of oxygen using the random choice method (RCM) adapted to supercomputing with an operator splitting technique. The resultant N-wave profiles are in good agreement with the experimental results. The numerical results clearly indicate that the wave-easing process due to the dispersive effect of vibrational relaxation plays a dominant role in determining the rise time of the N-wave.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1990.