Hydrocarbons pyrene

When a dilute solution of the polynuclear aromatic hydrocarbon pyrene in toluene is irradiated with ultraviolet radiation, it emits a violet... 

The structureless fluorescence spectra of crystalline pericondensed hydrocarbons, pyrene, perylene, and 1,12-benzperylene, on the other hand, are red-shifted by 6000 cm-1 from the 0"-0 molecular fluorescence band,103-105 and in the case of pyrene is virtually identical with the excimer band. As shown schematically in Figure 13, the molecular orientation in a... 

The condensed ring aromatic hydrocarbons pyrene (22), coronene (23), ovalene (24), and circumanthracene (25) have been the subject of... 

Abstract Pressure-sensitive paint (PSP) is applied to the areodynamics measurement. PSP is optical sensor based on the luminescence of dye probe molecules quenching by oxygen gas. Many PSPs are composed of probe dye molecules, such as polycyclic aromatic hydrocarbons (pyrene, pyrene derivative etc.), transition metal complexes (ruthenium(II), osumium(II), iridium(III) etc.), and metalloporphyrins (platinum (II), palladium(II), etc.) immobilized in oxygen permeable polymer (silicone, polystyrene, fluorinated polymer, cellulose derivative, etc.) film. Dye probe molecules adsorbed layer based PSPs such as pyrene derivative and porphyrins directly adsorbed onto anodic oxidised aluminium plat substrate also developed. In this section the properties of various oxygen permeable polymer for matrix and various dye probes for PSP are described. 

J. W. M. Wegener, E. A. Maier, G. N. Kramer, W. P. Cofino, The certification of the contents (mass fractions) of polycyclic aromatic hydrocarbons pyrene, benz(a)anthracene, benzo(a)pyrene, benzo(e)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene and indeno(l,2,3-cd) pyrene in fresh water harbour sediment CRM 535, EUR 17795 EN, 1997, European Commission, Luxembourg, pp. 51. 

Thebenol can be methylated to methebenol and acetylated on evaporation with 30 per cent, potassium hydroxide [7] or fusion with aniline hydrochloride [12] it is demethylated to northebenol, which, like thebenol itself, gives an iodhydrin on heating with concentrated hydriodic acid [7]. Thebenol contains an asymmetric carbon atom, but attempts to resolve it by condensing it with glucose residues yielded only decomposition products [12], The hydrocarbon pyrene [vi] is formed when thebenol is distilled with zinc-dust or reduced with hydriodic acid [7] pyrene is also obtained from thebaine under the same conditions [13]. 

It should not be assumed that all simple mixtures can be analyzed by either of the above techniques. Consider the aromatic hydrocarbon pyrene in the presence of an equal amount of anthracene. The ultraviolet absorption (and fluorescence excitation) spectrum of anthracene completely overlaps that of pyrene. It can be... 

Values for are usually obtained from batch experiments and for a given compound will vary depending on the soil or sediment as is illustrated in Table 3.4 for a polynuclear aromatic hydrocarbon, pyrene " a 15-fold difference. Consideration of the sorbent characteristics, it is clear that, for pyrene, there is no relation between sorption and pH or the amount of clay, however, the association between... 

The photocyanation of pyrene in a microchaimel through an oil-water interface was investigated by Ueno et al. [13]. The microchips employed are made of polystyrene by embossing with a silicone template. The phase transfer reaction proceeds in four steps as depicted in Figure 16.2. In the first step, a photoinduced electron transfer in the oil phase (polycarbonate) occurs from the aromatic hydrocarbon pyrene (DH) to the electron acceptor 1,4-dicyanobenzene (A). The cationic DH " radical is subsequently the target of the nucleophilic attack of the cyanide anion at the oil-water interface. The cyanated product DCN is insoluble in water and goes back into the oil phase. Experiments without a cyanide source (NaCN) in the aqueous phase show no reaction. Hence it can be excluded that the nudeophilic-substituted cyanide originates from the electron acceptor 1,4-dicyanobenzene. 

Figure 2. Open chains (spanning trees ) that could be used for an application of McWeeny s method via eq 16 (section V) in order to perform a ring-current calculation on the conjugated hydrocarbon pyrene (14) (a) the carbon-carbon cr-bond connectivity of pyrene (b) a continuous open chain (from this semi Hamiltonian molecular-graph ) for pyrene (c) circuit completing bonds associated with the open chain in part b. (Adapted and reprinted with permission from ref 3. Copyright 1997 Research Studies Press Ltd.)...

From the above-mentioned aromatic hydrocarbons, pyrene is for sure the most widespread excimer forming fluorescent probe. The fluorescence spectra of pyrene are known to display the characteristic vibronically resolved pyrene band with a maximum at 375 nm, together with a stractureless long-wavelength band (ca. 480 nm). Typically, only at concentrations of pyrene above ca. 10 mol dm , intermolecular excimer formation is clearly observed. For intramolecular excimer formation (concentration independent kinetics) the long-wavelength emission band can be observed for concentrations as low as 10 mol dm . ... 

Boschi, R. and Schmidt, W., Photoelectron spectra of delocalized Jt-s) ems. 2. Photoelectron spectra of polycycHc aromatic hydrocarbons, pyrene and coronene. Tetrahedron Lett., 25,2577,1972. 

---