In vivo mTHPC photobleaching in normal rat skin exhibits unique irradiance-dependent features

We report measurements performed on the normal skin of rats in vivo, which provide information on the photobleaching kinetics and mechanisms of the photosensitizer meso-tetrahydroxyphenyl chlorin (mTHPC). Loss of mTHPC fluorescence was monitored using in vivo fluorescence spectroscopy during photodynamic therapy (PDT) performed using 650 nm laser irradiation. The bleaching was evaluated for irradiances of 5, 20 and 50 mW cm(-2). Two distinct phases of mTHPC photobleaching were observed. In the first phase there was no obvious irradiance dependence in the loss of fluorescence vs fluence. The second phase was initiated by an irradiance-dependent discontinuity in the slope of the bleaching curve, after which the photobleaching rates showed an irradiance dependence consistent with an oxygen-dependent reaction process. To investigate the unusual shape of the in vivo bleaching curves, we measured the PDT-induced changes in O2 concentrations in mTHPC-sensitized spheroids irradiated with 2, 5 and 20 mW cm(-2) of 650 nm light. The oxygen concentration data indicated no unusual features within the range of fluences where the discontinuities in fluorescence were observed during in vivo spectroscopy. The fluorescence from the in vivo bleaching experiments thus reports a phenomenon that is not reported by measurements of the photochemical oxygen consumption in the spheroids.     

Fluorescence anisotropy imaging reveals localization of meso-tetrahydroxyphenyl chlorin in the nuclear envelope

We have measured the intrinsic fluorescence anisotropies of six photosensitizers in homogeneous solution, and we have imaged the anisotropies of these sensitizers in tumor cell monolayers using polarization-sensitive laser-scanning confocal microscopy. The intrinsic anisotropies are unremarkable and are within the approximate range of 0.2–0.27. In cells, however, very interesting behavior is exhibited by meso -tetrahydroxyphenyl chlorin (mTHPC). Polarization-sensitive images of mTHPC's fluorescence show a pronounced banding of alternating high and low anisotropy consistent with an ordering of the sensitizer in the nuclear envelope, indicating that this structure is a target of photodynamic damage with this sensitizer. None of the other sensitizers exhibits localization to the nuclear envelope. The frequency distributions of the intracellular anisotropies of the sensitizers exhibit variable peaks and widths. An unusual case is that of Photofrin, with a peak in its anisotropy frequency distribution of –0.12. The change from a positive intrinsic anisotropy in homogeneous solution to a negative value in cells suggests an environmentally induced change in the relative orientations of the absorption and emission dipole moments.     

An example of an iron (III) porphyrin with spin mixed ground state

The paper reports synthesis and physical characterisation of a new iron(III) porphyrin which shows unusual features of quantum mechanically mixed ground state in its magnetic properties. Magnetic susceptibility (300−3·6 K) and M?ssbauer spectroscopy (300−77 K) studies of the compound are described and discussed with reference to some bacterial ferricytochromeC' exhibiting similar spin-mixed ground state.     

Studies on some radical transfer reactions. Part I. Hydrogen atom abstraction from some organic substrates by ȮH radicals

Polymerization of methyl methacrylate was carried out in aqueous and nonaqueous media in the presence of some sulfonated and carboxylic organic compounds, hydroxyl radicals generated from hydrogen peroxide being used as initiators of polymerization. The occurrence of radical transfer reactions by way of hydrogen atom abstraction from the organic substrates by the ?H radicals was demonstrated by the detection of sulfonate and carboxyl endgroups in the respective polymers. It was found that the radical transfer reactions were more favored in aqueous media than in nonaqueous systems.     

Phase transformation studies on Mn−Al−C alloy,by DSC and electrical resistivity measurements

Phase transformation studies carried out on Mn?Al?C permanent magnet alloy employing DSC and electrical resistivity measurements, are reported and discussed. The transformation of the hexagonal Mn?Al phase (disordered and non-magnetic) to the ferromagnetic fct phase proceeds via the formation, in at least two stages, of the ordered orthorhombic phase. The activation energy for the formation of the fct phase is ≈34.65 kcal/mol. Microstructural changes occurring at various stages of the transformation are also studied.     

Synthesis,Characterization and Molecular Structure of a New Tetrameric Palladium(II) Complex Containing Schiff‐Bases Derived from AMTTO (AMTTO = 4‐amino‐6‐methyl‐1,2,4‐triazine‐thione‐5‐one)

The reactions of AMTTO = 4‐amino‐6‐methyl‐1,2,4‐triazine‐thione‐5‐one (AMTTO, 1 ) with 2‐hydroxybenzaldehyde (salicylaldehyde) and 4‐hydroxybenzaldehyde in methanol under reflux conditions led to the corresponding Schiff‐bases ( H₂L1 and H₂L2 ). The reaction of H₂L1 with palladium acetate in ethanol and additional recrystallization from toluene gave the tetrameric complex [Pd(L)]₄·2C₇H₈ ( 2 ). All compounds were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for H₂L1 at ?80 °C: space group P2₁/c with a = 1285.4(1), b = 707.7(1), c = 1348.2(1) pm, β = 109.32(1)°, Z = 4, R₁ = 0.0328, H₂L2 at ?80 °C: space group P4₃2₁2 with a = 762.5(1), b = 762.5(1), c = 4038.9(2) pm, Z = 8, R₁ = 0.025 and for 2 at ?103 °C: space group C2/c with a = 2862.5(6), b = 2847.6(6), c = 1727.8(4) pm, β = 105.18(3)°, Z = 8, R₁ = 0.0704.     

Spectrophotometric determination of vanadium(v) and its application to vanadium steels containing chromium, molybdenum, tungsten and manganese

A newly synthesized reagent, N-o-toluoyl-N-o-tolylhydroxylamine is used in a sensitive and selective spectrophotometric method for determination of vanadium(V). The method has been successfully applied to vanadium determination in Mn-Mo-Cr-V steels. The system in 2-6M hydrochloric acid medium obeys Beer's law at 510 nm in the range of vanadium concentration from 0.5 to 10.0 mug ml .     

Kinetic study of Cr(VI) sorption on MnO2

The kinetics of adsorption of chromate ions has been investigated radiometrically over a wide range of concentration of chromate ions (10^–6–10^–2M) and temperature (303–323 K). The kinetics of the process follows essentially a first order rate law with respect to adsorptive concentration and obeys the Freundlich adsorption isotherm in the concentration range studied. In addition, the kinetics of desorption of the preadsorbed species also follows a first order rate law and the activation energy for desorption is greater than that of the adsorption process. On the basis of an adsorption kinetic study, the thermodynamic parameters have been calculated. Infrared spectroscopy has shown the chemical interaction of chromate ions on the surface of MnO₂.     

N‐(2‐Amino­benz­yl)‐N,N‐bis­(quinolin‐2‐ylmeth­yl)amine

The title new diquinaldine derivative, C₂₇H₂₄N₄, forms mol­ecular assemblies organized by inter­molecular quinoline π–π stacking [3.356 (3) and 3.440 (3) Å] and both inter‐ and intra­molecular N—H⋯N hydrogen bonds [3.039 (3)–3.104 (3) Å and 129 (2)–172 (2)°]. The combination of such inter­actions provides readily definable contacts that propagate along each crystallographic axis.     

Synthesis,Characterization and Crystal Structure of Dimeric {[(AMTTO)2Ag]NO3}2 (AMTTO = 4‐Amino‐6‐methyl‐1, 2, 4‐triazine‐3(2H)‐thione‐5‐one)

The reaction of 4‐Amino‐6‐methyl‐1, 2, 4‐triazine‐3(2H)‐thione‐5‐one (AMTTO, 1 ) with silver nitrate in methanol led to the dimeric complex {[(AMTTO)₂Ag]NO₃}₂ ( 2 ). 2 was characterized by elemental analyses and IR spectroscopy as well as by X‐ray structure analysis. Crystal data for 2 at ?80 °C: crystal system orthorhombic, space group P2₁2₁2₁ with a = 1043.6(1), b = 1329.6(1), c = 2358.4(1) pm, Z = 8 and R₁ = 0.037. The cation possesses a highly distorted linear coordination sphere in the solid state.