Study of the torsion-rotation Hamiltonian for symmetric tops using the millimeter wave spectrum of methyl silane

The torsion-rotation Hamiltonian for symmetric tops has been tested in methyl silane by combining recent anticrossing molecular beam measurements in the ground torsional state (v = 0) with pure rotational spectra taken for v as high as 4. The earlier microwave data set which consisted of J = 1 ← 0 and 2 ← 1 has been greatly extended by studying millimeter transitions for J = 4 ← 3, 5 ← 4, and 13 ← 12. An analysis of the 72 rotational frequencies for v ≤ 2 and the 15 anticrossing data for v = 0 yielded an excellent fit using 14 rotational, torsional, and distortion constants including the effective values for the A rotational constant and the barrier height V₃. No satisfactory fit could be obtained when the data set was extended to include measurements for (v = 3) or (v = 4). For each of these higher torsional levels, the difference between the observed frequencies and the predictions based on the best (v ≤ 2) constants can be expressed in terms of a shift δB_v in the B rotational constant, where δB_v is a smooth function of the torsional energy. This disagreement is of particular interest because it may result from the fact that the molecule passes from hindered to free rotation as v is increased from 2 to 4. The possibility of perturbation by a low-lying vibrational level is considered briefly. The information contained in the different types of spectra is discussed; the redundancy relations are treated and a Fourier expansion of the diagonal torsional matrix elements is introduced. For ¹²CH₃²⁹SiH₃, ¹²CH₃³⁰SiH₃, and ¹³CH₃²⁸SiH₃ pure rotational spectra for v = 0 were studied briefly in natural abundance. The results were combined with existing data for two deuterated symmetric rotors to obtain a structure based only on symmetric top rotational constants.     

Indoprofen upregulates the survival motor neuron protein through a cyclooxygenase-independent mechanism

Most patients with the pediatric neurodegenerative disease spinal muscular atrophy have a homozygous deletion of the survival motor neuron 1 (SMN1) gene, but retain one or more copies of the closely related SMN2 gene. The SMN2 gene encodes the same protein (SMN) but produces it at a low efficiency compared with the SMN1 gene. We performed a high-throughput screen of approximately 47,000 compounds to identify those that increase production of an SMN2-luciferase reporter protein, but not an SMN1-luciferase reporter protein. Indoprofen, a nonsteroidal anti-inflammatory drug (NSAID) and cyclooxygenase (COX) inhibitor, selectively increased SMN2-luciferase reporter protein and endogenous SMN protein and caused a 5-fold increase in the number of nuclear gems in fibroblasts from SMA patients. No other NSAIDs or COX inhibitors tested exhibited this activity.     

Rational design of ordered mesoporous carbon with controlled bimodal porosity via dual silica templating route

Combining both nano-replication and nano-imprinting techniques using dual silica templates provides a simple way to synthesize ordered mesoporous carbons with bimodal pore size distributions ( approximately 1.5 nm and approximately 3.5 nm).     

Synthesis and fluorescence enhancement of oligophenylene-substituted calix[4]arene assemblies

Tetra-oligophenylene substituted calix[4]arene assemblies containing up to three phenylene units have been synthesized by a convergent approach using Suzuki cross-coupling and their optical properties were investigated and compared with the corresponding monomer.     

Dihydrogen-bond-promoted catalysis: catalytic hydration of nitriles with the indenylruthenium hydride complex (eta(5)-C(9)H(7))Ru(dppm)H (dppm = bis(diphenylphosphino)methane)

The indenylruthenium hydride complex (eta(5)-C(9)H(7))Ru(dppm)H was found to be active in catalyzing the hydration of nitriles to amides. The chloro analogue (eta(5)-C(9)H(7))Ru(dppm)Cl was, however, found to be inactive. Density functional theory calculations at the B3LYP level provide explanations for the effectiveness of the hydride complex and the ineffectiveness of the chloro complex in the catalysis. It is learned that the presence of a Ru-H.H-OH dihydrogen-bonding interaction in the transition state lowers the reaction barrier in the case of (eta(5)-C(9)H(7))Ru(dppm)H, but in the chloro system, the corresponding transition state does not contain this type of interaction and the reaction barrier is much higher. A similar dihydrogen-bond-promoting effect is believed to be responsible for the catalytic activity of the hydrotris(pyrazolyl)borato (Tp) ruthenium complex TpRu(PPh(3))(CH(3)CN)H in CH(3)CN hydration. The chloro analogue TpRu(PPh(3))(CH(3)CN)Cl shows no catalytic activity.     

Synthesis and functional properties of strongly luminescent diphenylamino end-capped oligophenylenes

Two novel homologous series of oligophenylenes (OPPs) symmetrically end-capped with diphenylamino groups and asymmetrically end-capped with anthryldiphenylamino groups were successfully synthesized by a convergent approach with use of palladium-catalyzed homo- and cross-coupling of arylboronic acids. The absorption maxima of both diphenylamino end-capped OPP series do not vary with the chain length although the molar absorptivities increase sequentially. On the other hand, the emission maxima slightly shift to longer wavelengths when the phenylene unit increases in the series. All the diphenylamino end-capped oligomers exhibit very large fluorescence quantum yields (81-89%). They also exhibit low first ionization potentials, corresponding to the oxidation of the triarylamino moiety, which are essentially unaffected by the oligomeric length extension. The good thermal stabilities of these oligomers allowed the fabrication of multilayer light-emitting devices and their investigations.     

Dimethylglyoximkomplexe des Kobalts(III) mit aromatischen Diaminen Über α-Dioximkomplexe der Übergangsmetalle, 37. Mitt.

Zusammenfassung Durch Oxydation von Kobalt(II)salz-Lösungen in Anwesenheit von Dimethylglyoxim und aromatischen Diaminen wurden unter doppelter Umsetzung 41 Salze der [Co(HD)₂(o-Phenylendiamin)₂]⁺, [Co(HD)₂(m-Phenylendiamin₂])⁺, [Co(HD)₂-(2-Methyl-p-phenylendiamin)₂]⁺ und [Co(HD)₂(N-Dimethyl-p-phenylendiamin)₂]⁺-Kationen erhalten. Die Koordination von zwei Diaminliganden im Kobalt(III)-bis-dimethylglyoximin-Kern bestätigt dietrans-Konfiguration der [Co(HD)₂(Diamin)₂]⁺-Komplexe. Diese Annahme wurde auch durch UR-spektroskopische Untersuchung bestätigt.

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On-dioxime complexes of transition metals, XXXVII. Cobalt(III)-dimethylglyoxime complexes with aromatic diamines

The oxidation of cobalt(II) salts in presence of dimethyl-glyoxime and aromatic diamines, has been studied. A series of 41 novel complex salts of the cations [Co(HD)₂(o-phenylendiamine)₂]⁺, [Co(HD)₂(m-phenylendiamine)₂]⁺, [Co(HD)₂(2-methyl-p-phenylendiamine)₂]⁺ and [Co(HD)₂(N-dimethyl-p-phenylendiamine)₂]⁺ has been prepared and characterized by means of double decomposition reactions.The coordination of 2 diamine molecules to the Co(III)-dimethylglyoximine-skelet confirms thetrans-configuration of the [Co(HD)₂(diamine)₂ ⁺ complexes.

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Mit 2 Abbildungen     

Quantification of the Activation Capabilities of Lewis/Brφnsted Acid for Electrophilic Trifluoromethylthiolating Reagents

Summary of main observation and conclusion Electrophilic trifluoromethylthiolation has emerged as an important and efficient methodology for installing the SCF3 moiety onto an array of organic molecules.Due to the low reactivities of trifluoromethylthiolating reagents,these transformations often require activation through an exogenous Lewis/Br0nsted acid.We report herein the quantification of the activation capabilities of Lewis/Br0nsted acids for trifluoromethylthiolating reagents through computing the differenee in trifluoromethylthio cation donor ability(Tt+DA)between the"activated"and"unactivated"reagent.A moderate correlation is found to exist between the activation capability and Lewis acidity.     

Trace element profiles in the hair of Nasopharyngeal carcinoma (NPC) patients

The trace element profiles of the scalp hair of NPC patients, aged between 30 and 69, were measured using neutron activation analysis and compared with those of normal healthy people within the same age bracket. The washing method of using detergent and washing powder was found to be comparable to that of using ether. Difference in the mean concentration of each element in the two groups was tested by Student's t-test. A significantly lower value of strontium (Sr) and significantly higher values of arsenic (As), iron (Fe) and vanadium (V) were found in the hair of NPC patients. The relative values of As and Fe found were consistent with the results of other findings on NPC patients, using different measuring methods. The V content in the hair of NPC patients was three times that of healthy people.