0000000000328762
AUTHOR
W. Wacławek
Determination of the atmospheric precipitation pH value on the basis of the analysis of lichen cationoactive layer constitution
Studies of equilibria and kinetics of the ion exchange process between the surrounding (water solution) and lichens prove that the number of mobile hydrogen ions bonded in lichens depends on the concentration of hydrogen ions in the precipitation with which the lichens are in contact and the type and concentration of other cations contained in the precipitation. The measurement of these values was suggested; as a result, it enabled to determine the pH of precipitation by determination of mobile cations bonded in exposed or naturally grown lichens. The studies were conducted on Hypogymnia physodes lichens.
Evidence of Back Charge Transfer in DMBP-TCNQ3
The single crystal conductivity of (N,N'-dimethyl-4,4'-bipyridinium)2+(7,7,8,8-tetracyanop- quinodimethanide)3 2-, DMBP-TCNQ3, exhibits an anomaly at 170 K which may be attributed to a phase transition and, also, a change in activation energy at 135 K which may be attributed to the onset of extrinsic behaviour. Above 135 K the conductivity varies as σ = σ0 exp(-E2/kT) where σ300K. = 1 S cm-1 and Ea = 0.18 eV. In the high temperature region the thermoelectric e.m.f. saturates to a temperature independent value of S = - 20 μVK-1 whereas for the related monoquaternised salt, [N-phenyl-4-(4'-pyridyl)-pyridinium]+(TCNQ)2 -, ØBP-TCNQ2, S = - 55 μVK-1. The thermoelectric data may be interpreted in…
Spectral studies of zinc octacarboxyphthalocyanine aggregation
The association of zinc octacarboxyphthalocyanine, was studied using UV–vis absorption and fluorescence emission spectroscopy; the effects of dye concentration, pH and solvents on spectra were discussed. Calculations showed that the dye dimerized in aqueous solutions ranging from 5.0 × 10−7 to 5.0 × 10−5 mol/dm3, at 25 °C. The dimerization constant of 106 dm3/mol and the spectral Q band shift of 1185 cm−1 imparted by dimerization indicated strong π–π interactions between phthalocyanine molecules. Red S1 fluorescence of the dye monomer was observed in various solutions which was quenched owing to molecular association and other factors. The strong influence of pH on both aggregation and fluo…
Spectroscopic and electrochromical properties of metallophthalocyanines in silicate bulks and thin films prepared by the sol–gel method
Abstract Magnesium phthalocyanine (MgPc) and praseodymium bisphthalocyanine (Pr(Pc) 2 ) have been entrapped in bulks and thin films of porous silicate xerogels prepared via the sol–gel method. The electronic absorption data obtained for the complexes immobilized in bulk sol–gel matrices indicate the formation of complex equilibria between their monomeric forms and respective agglomerates. Thin xerogel films doped with metallophthalocyanines and connecting two slides of transparent ITO electrodes display changes in the absorption spectra caused by varying of the applied voltage. These changes appear to be reversible in certain ranges of the applied voltages.
Ion equilibrium in lichen surrounding.
In laboratory conditions, the ionic equilibriums between a solution and a cation-active layer of epiphytic lichens Hypogymnia physodes immersed in the solution were examined. It was found that such equilibriums, due to exchange of mobile cations: H, Na, K, Ca, and Mg, are established in natural conditions between a lichen and atmospheric water.
Spectroscopic and physicochemical properties of rare-earth phthalocyanines entrapped in sol-gel glasses
Abstract The electronic absorption spectra of samarium and neodymium phthalocyanines in DMSO and entrapped in glasses obtained via the sol-gel technique have been obtained. Decrease in concentration of metallophtalocyanines in DMSO leads to observed changes in the relative intensifies of the two bands in the Q-band region. This behavior could be explained by the shifts in equilibrium between the LnPc 2 and LnPc + forms, caused by the dilution. In view of this interpretation, the entrapment of the metallophthalocyanines in the sol-gel glass matrices shifts the diphthalocyanine ⇆ monophthalocyanine equilibrium towards the monophthalocyanine (LnPc + ) form.
Quantitative relations between different concentrations of micro- and macroelements in mosses and lichens: the region of Opole (Poland) as an environmental interface in between Eastern and Western Europe
We examined the concentration of selected metals: Al, Mn, Fe, Cu, Zn, Cd and Pb, as well as activity of 137Cs in samples of moss and lichen, collected in the area surrounding Bory Stobrawskie, a wood complex situated in southern Poland. The concentration of metals was determined by atomic absorption spectrometry. The activity of 137Cs was determined by gamma spectrometry. We used these results, as well as results published in the literature, to determine the correlation between the concentration of analytes in lichens and in mosses. The analysis of the function ln(cx,moss) = lna + bln(cx,lichen) indicated with high degree of certainty that the concentration levels of analytes accumulated in…
Investigation of phthalocyanine crystals exposed to NO2 ambient gas
Crystals of free base phthalocyanine (H2pc) and its unsubstituted metal derivatives Mpc (where M=Ni, Cu, Zn, Pb, and pc=C32H16N8 2−=phthalocyanine ligand) were examined after being exposed to NO2 ambient gas. Scanning electron microscopy (SEM) supported by X-ray microprobe analysis (EDAX), UV–Vis and FTIR spectroscopy as well as X-ray powder diffractometry (XRD) were applied to study the crystals chemistry and surface morphology. The NO2 molecules were found to penetrate the crystal unit which led to the breakdown of the phthalocyanine macrocycle. The surface of the doped crystals has been scaled and covered by a layer composed predominantly of phthalimide. Despite vacuum desorption, it has…