NIR emitting ytterbium chelates for colourless luminescent solar concentrators

A new oxyiminopyrazole-based ytterbium chelate enables NIR emission upon UV excitation in colorless single layer luminescent solar concentrators for building integrated photovoltaics.     

An elementary method for the calculation of the set of character degrees of somep-groups

Letq be a power of a prime numberp. In this work, we present an elementary method to find out the set of irreducible character degrees of the Sylowp-subgroups ofSp(2n,q) whenq is odd. This simplifies the proof of Previtali [4], where this result was first obtained. This method also works for the groups of unitriangular matrices over finite fields. Research supported by the Basque Government and the University of the Basque Country UPV 127.310-EB160/98.     

Determination of lysinoalanine by high performance liquid chromatography

This work suggests an HPLC method for qualitative and quantitative determination of N^ε(2-amino-2-carboxyethyl)-L -lysine (LAL). LAL was released from total hydrolysates of various proteins of animal origin and derivatized with dansyl chloride. The performance of two different columns, Spherisorb 3S TG and μ-Bondapack C₁₈, was compared; better resolution and quantitative response were obtained with the former. The mobile phase was a mixture of 0.01 M phosphate buffer (pH 7) and acetonitrile. Linear response and quantitative repeatability were tested for both detectors used (UV-Vis set at 254 nm; fluorimetric set at λ_ex(max) = 360 nm and λ_em(max) = 525 nm). For LAL standard the minimum detectable amount was 0.05 ng, whereas for LAL in actual samples the amount was 0.5 ng (40 μg/g of analyzed proteins). Good analytical repeatability was obtained, resulting in CV % of 4.7 and 3.8 for UV and fluorimetric detectors, respectively. LAL recovery was determined using both detectors; the values obtained were 94 % (fluorimetric) and 92 % (UV). Greater noise levels were observed with the fluorimetric detector and its higher sensitivity could not, therefore, be fully utilized. The highest amounts of LAL were found in the casein (2816 μg/g) and cooked albumin (615 μg/g) samples.     

Groups with three real valued irreducible characters

We obtain strong restrictions on the structure of a Sylow 2-subgroup of a group with at most three real valued irreducible characters. This extends results of Iwasaki, who studied groups with at most two real valued irreducible characters. This research was partially supported by the Spanish Ministerio de Educación y Ciencia, MTM2004-06067-C02-01 and MTM2004-04665, and the FEDER. The first author was also supported by the Programa Ramón y Cajal and the Generalitat Valenciana.     

Dielectric tensor and optical spectra of quaterthiophene crystals

We present an approach to the microscopic calculation of the dielectric tensor near the resonances of mechanical Frenkel excitons in a vibronic coupling regime with one effective mode. The model, applied to the prototypical quaterthiophene crystal, is based on a discrete distribution of charges for the evaluation of the molecular transition moment, whilst the coulombic interactions responsible for the exciton delocalization in the crystal are calculated by the Ewald method. From the calculated tensor we simulate absorbance and reflectance spectra and by a direct comparison with the experimental ones, we identify the origin of some shoulders present in the spectra.     

Vibrational Spectra of Anhydrous Lanthanum,Europium, Gadolinium,and Dysprosium Nitrates and Oxinitrates

IR. and Raman spectra of LnONO₃ (50–4,000 cm^?1, Ln?La, Gd, Eu, and Dy) are reported and discussed. The low frequency region of the spectra reflects the cubic structure of these compounds. The dimensions of the cubic unit cells determined by X-Ray powder diagrams are: 12.81 ± 0.05 Å for EuONO₃, 12.69 ± 0.05 Å for GdONO₃, and 12.67 ± 0.05 Å for DyONO₃. The vibrational frequencies of the nitrato group are consistent with a bidentate nitrate of C_2v symmetry. The synthesis of anhydrous Ln (NO₃)₃ (Ln?La, Gd, Eu, and Dy) by dehydration of the corresponding penta- or hexahydrates is described. The IR. and Raman spectra (50-4,000 cm^?1) are analysed. Splitting of the bands point to a complex structure of these compounds. All six vibrational modes of the nitrato group are observed and the data are again consistent with bidentate NO^?₃ moieties. Finally, an analytical control of the purity of Ln (NO₃)₃ is suggested.     

Change of the reaction pattern by methodological variations in a multicomponent assembly promoted by Ni complexes

The pi-allylnickel complex formed by the addition of trimethylsilyl chloride (TMSCl) to a mixture of [Ni-(cod)2] (cod = 1,5-cyclooctadiene) and a vinyl ketone (Mackenzie complex) carbometalates an acetylene in a completely regioselective manner resulting in the formation of the corresponding vinyl nickel species. This intermediate is capable of controlled quenching in a variety of ways to give different types of compounds: under a CO atmosphere, an acylnickel species is formed that ensues from the carbometalation of the enol ether double bond to form cyclo-pentenone derivatives. Alternatively, if acetylene is present in excess and CO is absent, another acetylene moiety will replace the CO and cyclohexadienes will result instead. Finally, if only an excess of the vinyl ketone is used, the product from a slow double addition of the vinyl ketone across the triple bond is formed. The regioselectivities obtained by the present method are different from those obtained by the involvement of nickel acyclopentadienes as intermediates when the order of addition is reversed.