The meaning of the very different OH bandshapes in infrared fundamental and overtone regions of H-bonded methanol

Infrared spectra of methanol in solvents were discussed in the fundamental and overtone region in dependence on the temperature. One absorption band is observed in the fundamental region of the OH stretching vibration, however, the overtone band is splitted into two or more bands. The intensity ratio of the overtone bands changes characteristically with the temperature and with the H-bond strength. This behavior will be explained by different OH transitions, taking into account the OO vibration. A modified Lippincott-Schroeder procedure was used for the calculations of energy values. The splitting of the overtone bands could be assigned to the transitions E(v=0,v′) → E(v=2,v′) and E(v=0,v′) » E(v=2,v′+1), with v′ as OO vibrational quantum-number.     

Some spirobiindane based 1H-pyrazolo [3,4-b] quinoline chromophore as novel chromophore for light-emitting diodes

An influence of phenoxy groups for the luminescent and electroluminescent properties of spiro-compounds with pyrazolo [3,4-b] quinoline structure (fluorophore) chromophore has been studied. All the compounds exhibit strong fluorescence in solution and in solid state as well. The prepared compounds were used as dopant chromophore in PVK polymer matrices for electroluminescent (EL) and light-emitting diode (LED) devices with configuration ITO/PEDOT-PSS/PVK/PQ/Ca/Al. Role of the bathochromic shifts and solvent polarity in absorption and photoluminescent maxima is considered. Relation between the number of pyrazoloquinoline chromophore and presence of phenyl group on the fluorescence spectra is explored. Polarizability of the particular pyrazoloquinoline compounds on the solvatochromic effects is investigated. Possible ways of enhancement of the brightness in the light-emitting properties of the mentioned chromophore are discussed.     

A Simple Method for the Preparation of Substituted Phenoxyacrylic Acid Phenyl Esters

A simple and efficient synthesis of phenoxyacrylic acid phenyl esters via one pot esterification and Michael-type addition starting from propynoic acid and an excess of an appropriate phenol is described.     

Oxygen induced surface segregation of Cu on the Au0.7Cu0.3(100) surface

The oxygen induced surface segregation of Cu on the Au_0.7Cu_0.3(100) surface was investigated by means of LEED and AES techniques. The dissociative adsorption of O₂ did not take place on this clean surface for a long time exposure at least up to 10⁴ L, and so the oxygen was forcibly introduced onto the surface through a pre-deposition of few a layers of Cu and its successive oxidation. The oxygen coverage was controlled by a heat treatment, which leads the system to a thermal equilibrium state. For the clean surface, the segregation of Au was clearly observed and the surface concentration of Au was estimated to be about 86%, greater than the bulk concentration of 70%. At low coverages below 0.16 ML, no remarkable oxygen induced segregation of Cu was observed. But, above 0.2 ML, the surface concentration of Cu was proportional to the oxygen coverage. The (2 × 4) LEED pattern was observed in a wide range of oxygen coverage. The maximum intensity of the (2 × 4) was observed at about 0.45 ML.     

Oxidation of 2,4,6-trichlorophenol catalyzed by iron phthalocyanines covalently bound to silica

The covalent attachment of an iron phthalocyanine with chlorosulfonyl substituents (FePcSO₂Cl) onto a functionalized 3-aminopropyl-silica has been achieved. This supported catalyst FePcSO₂Cl-silica is able to degrade a recalcitrant pollutant like 2,4,6-trichlorophenol (TCP) with hydrogen peroxide as oxidant. In order to improve the catalytic efficiency of the grafted iron phthalocyanine complex, modifications of the macrocycle substituents, passivation of the silica surface, variation of the loading of the carrier and addition of an organic cosolvent to the reaction mixture were carried out.     

Application of semi-permeable membrane dialysis/ion trap mass spectrometry technique to determine polybrominated diphenyl ethers and polychlorinated biphenyls in milk fat

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are hazardous food contaminants, their maximum legally allowable levels in food and environment are in the low pg g⁻¹ range. Therefore some highly selective and sensitive analytical methods must be used to determine them. The 96/23/EC Directive implemented by EC Decision of 12 August 2002 requires recovery rate of an analyte at a concentration below 1 ng g⁻¹ within the 50–120% range at relative standard deviation (RSD) as low as possible.     

Ring opening in the amination of 3-X-1,2,4-triazines [1,2]. A 15N study

Evidence, based on ¹⁵N-labelling studies, has been obtained that the amino-dechlorination of 3-chloro-1,2,4-benzotriazine by potassium amide in liquid ammonia occurs according to an S_N(AE)^ipso process, while the amino-dechlorination of 3-chlorophenanthro[9,10-e]-1,2,4-triazine reacts for more than 90% according to a process involving a ring opening reaction [S_N(ANRORC)^ipos substitution].