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Recent work has been developed on two new classes of neutral porphyrazine complexes of formulas [(PdCl2)4Py8PzM]·xH2O (Py8Pz = octakis(2-pyridyl)porphyrazinato anion; M = MgII(H2O), ZnII, PdII) and [{Pd(CBT)2}4Py8PzM]·xH2O (M = MgII(H2O), ZnII; CBT = m-carborane-1-thiolate anion). Characterization of all the species has been conducted by IR and UV-visible spectral measurements in a systematic comparison with the corresponding already known mononuclear species [Py8PzM] (M = MgII(H2O), ZnII) and the mono-PdII analogue isolated and presented here for the first time. Comparison includes also the two parent classes of pentanuclear tetrapyrazinoporphyrazines having the more extended π-electron delocalized macrocyclic core Py8TPyzPz. The reported new classes of pentanuclear complexes behave as active photosensitizers in photodynamic therapy (PDT), and due to the high boron content of the CBT derivatives, perspectives for them are open of application in the field of bimodal PDT/BNCT (boron neutron capture therapy) anticancer treatments.

The current study describes the synthesis, electrochemical, computational, and photochemical properties of octa (3-hydroxypropylthio) substituted cobalt (II) (4), copper (II) (5), nickel (II) (6) and zinc(II) (7) phthalocyanine derivatives. These novel compounds were characterized by elemental analysis, 1H, 13C NMR, FT-IR, UV-Vis, and MS. The redox behaviors of these metallophthalocyanines were investigated by the cyclic voltammetric method. The optimized molecular structure and gauge-including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of these phthalocyanines in the ground state had been calculated by using B3LYP/6-31G(d,p) basis set. The outcomes of the optimized molecular structure were given and compared with the experimental NMR values. The photochemical properties including photodegradation and singlet oxygen generation of zinc(II) phthalocyanine were studied in DMSO solution for the determination of its photosensitizer behaviors. © This work is licensed under a Creative Commons Attribution 4.0 International License.

A review of publications on the synthesis and properties of a family of compounds called perinones was carried out. The basic molecule has been known for several decades mainly as a photostable pigment, and in recent years it has become increasingly used in organic electronics. This paper describes the methods of synthesis of low molecular weight compounds and polymers based on that molecule; the basic spectroscopic, photochemical, electrochemical and electronic properties important for the construction of organic electronics and optoelectronics devices are also discussed.

Dissolved organic matter (DOM) is a ubiquitous component in effluents, DOM discharged with an effluent can affect the composition and properties of natural DOM in the receiving waters. As the photophysical and photochemical properties of effluent DOM can be changed by wastewater treatment processes, the effect of UV/chlorine treatment on the photophysical and photochemical properties of DOM was investigated using Suwannee River fulvic acid (SRFA) and Suwannee River natural organic matter (SRNOM) as representatives. Results showed that the absorbance of the two DOM was significantly decreased. The evolution trends of three representative photophysical parameters upon increase of chlorine dosages were observed. Also, a decrease in DOM aromaticity, molecular weight and electron-donating capacity was observed upon increasing chlorine dosage. Quantum yields of excited triplet state of DOM (3DOM*), singlet oxygen (1O2) and hydroxyl radicals (·OH) first decreases and then increased in the UV/chlorine systems upon increasing chlorine dosages due to the different reaction pathways of the two DOM. Moreover, 3DOM* can not only be regarded as a "controller" of other reactive intermediates, but also effectively promote the photodegradation of bezafibrate, which is classified as a persistent organic contaminant. This study gives deep insights into effects of UV/chlorine on the photophysical and photochemical properties of DOM, and is helpful for understanding the dynamic roles of DOM in the photodegradation of micropollutants.

The aim of the present paper was to optimize the properties of phenothiazine photosensitizers (PSs), Azure B and its monobrominated derivative. They were entrapped in multilamellar liposomes of egg phosphatidylcholine (EPC) and dipalmitoylphosphatidylcholine (dpPC). The higher partition coefficient of both PSs in the EPC/water system compared with that of both PSs in the dpPC/water system allowed the selection of EPC to be used for the development of third generation photosensitizers. The optimal phospholipid/phenothiazine ratio and the location of these dyes in the lipid bilayer systems were established. These dyes were found to be located within the polar head group region of the lipid bilayer, which would enhance the effectiveness of the irradiation procedure. In addition, the encapsulation of both photosensitizers in liposomes led to a decrease in the aggregation of these compounds, and consequently to an increase in their singlet oxygen quantum yield (ϕΔ). The encapsulation of the PSs in lipid vesicles significantly increased their photochemical reactivity, doubling the ϕΔ value of AzBBr and increasing that of AzB by 60%. The results obtained demonstrate that the vehiculization of these PSs in liposomes allowed the development of third generation photosensitizers with better photochemical properties to be used in potential therapeutic applications. Fil: Vara, Jimena. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica; Argentina Fil: Sanchez, Julieta Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Química. Cátedra de Química Biológica; Argentina Fil: Perillo, Maria Angelica. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Química. Cátedra de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina Fil: Ortiz, Cristina Susana. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Farmacia; Argentina

A poly(ethylene glycol) (PEG)-conjugated silicon(IV) phthalocyanine axially substituted with (PEG1000) chains (SiPc-PEG) was synthesized, and this novel phthalocyanine was characterized by [Formula: see text]H-NMR, FT-IR and UV-Vis spectrophotometric methods. Elemental analysis data were beneficial for the evaluation of the chemical structure of the new compound. The total number of (O–CH[Formula: see text]–CH[Formula: see text] units was calculated as 44 and the structure of the new PEG-conjugated silicon phthalocyanine was determined by the use of integral areas in [Formula: see text]H-NMR spectrum and the ratio of SiPc:PEG1000 was found as 1:2. The photophysical and photochemical properties were determined in both DMSO and aqueous solutions. In addition, the photocytotoxicity of the novel PEG-conjugated silicon(IV) phthalocyanine was also examined by testing against human cervical-carcinoma (HeLa) and hepato-carcinoma cells (HuH-7). The IC[Formula: see text] value for the SiPc-PEG compound was determined as 0.28 [Formula: see text]M for HeLa cells and 0.4 [Formula: see text]M for HuH-7 cells. These results imply that HeLa cells are apparently more responsive to photodynamic therapy (PDT) treatment by SiPc-PEG than HuH-7 cells at low concentrations (up to 0.5 [Formula: see text]M) of the studied photosensitizer. Additionally, SiPc-PEG showed antibacterial activity against Escherichia coli at 48 h of incubation, the viabilities of E.coli cultures exposed to 1000 [Formula: see text]g/mL and 2500 [Formula: see text]g/mL SiPc-PEG concentration were reduced by about 90%, and the additional growth inhibitory effect of photoactivation was also observed clearly at these efficient concentrations. To conclude, the novel compound may have a high potential for photodynamic therapy.

Date du colloque: 12/2008; Photosensitive materials attract many attention due to their potential application in optical devices such as optical data storage, optical communication, ...[1]. Coumarines and their analogues are well-known for their reversible photoinduced cyclodimerisation properties, leading to cyclobutane-based dimers (scheme) [2]. This equilibrium can be tuned according to the wavelength which is applied, and the resulting systems are of course dramatically structurally and electronically different. Therefore, the coumarine system offers a unique opportunity for applications in various fields involving conjugated molecular frameworks. In the area of photonics and nonlinear optics one of the great advantages of functionalized materials lies on the photochemical properties of the polymer. In the present work, homo- and copolymers built from the free radical polymerization of methacrylic monomers incorporating a coumarin side-group have been synthesized and structurally characterized. Results of photochemical and optical activities of the corresponding polymers will be presented.

Escherichia coli photolyase catalyzes the repair of cyclobutane pyrimidine dimers (CPD) in DNA under near UV/blue-light irradiation. The enzyme contains flavin adenine dinucleotide (FAD) and methenyltetrahydrofolate (MTHF) as noncovalently bound light sensing cofactors. To study the apoprotein-chromophore interactions we developed a new procedure to prepare apo-photolyase. MTHF-free photolyase was obtained by binding the C-terminal His-tagged holoenzyme to a metal-affinity column at neutral pH and washing the column with deionized water. Under these conditions the flavin remains bound and the defolated enzyme can be released from the column with 0.5 M imidazole pH 7.2. The MTHF-free protein was still capable of DNA repair, showing 70% activity of native enzyme. Fluorescence polarization experiments confirmed that MTHF binding is weakened at low ionic strength. Apo-photolyase was obtained by treating the His-tagged holoenzyme with 0.5 M imidazole pH 10.0. The apo-photolyase thus obtained was highly reconstitutable and bound nearly stoichiometric amounts of FAD(ox). Photolyase reconstituted with FAD(ox) had about 34% activity of native enzyme, which increased to 83% when FAD(ox) was reduced to FADH(-). Reconstitution kinetics performed at 20 degrees C showed that apo-photolyase associates with FADH(-) much faster (k(obs) approximately 3,000 M(-1) s(-1)) than with FAD(ox) (k(obs)=16 [corrected] M(-1) s(-1)). The dissociation constant of the photolyase-FAD(ox) complex is about 2.3 microM and that of E-FADH(-) is not higher than 20 nM (pH 7.2).

The synthesis and characterisation of photophysical, electrochemical and photochemical properties of rulhenium(II) polypyridyl containing hydroquinone triazole or pyrazole moieties are described. The characterisations described involve, HPLC, ^Hnmr, UV/vis/NIR spectroscopy, fluorimetry, electrochemistry, spectroelectrochemistry, laser flash photolysis, and resonance Raman spectroscopy. In the main chapter of this thesis the investigation of a series of Ru(II) complexes bound to pyridyltriazole ligands bridged to pendent electroactive phenol, hydroquinone and quinone moieties is described. A novel synthesis for oxidation of the hydroquinone containing complex is described, employing benzeneselininc acid which, in a one pot reaction under very mild conditions, the hydroquinone may be completely oxidised without concomitant oxidation of the quinone. None of the complexes described exhibit intramolecular electron transfer from any of the electroactive groups under neutral conditions. This was associated with endoergonic AG values for intramolecular electron transfer in these complexes under neutral conditions. At high pH however, intramolecular electron transfer was observed in all complexes containing the electroctive aryl groups. This was associated with intramolecular hole transfer from the Ru(III)* to the phenolate, semiquinone or anionic hydroquinone formed from these ligands at high pH. This electron transfer is ranges around 2 x 10() s-1 in neutral acetonitrile, it is therefore rather a slow transfer, however, the resulting charge separated state is stable over several microseconds. The electron transfer processes also persist at cryogenic temperatures, and outside the glass phase are largely temperature independent. These complexes were therefore described as simple abiotic models for photosynthesis, this is particularly the case for the hydroquinone containing complex, which also exhibits an electrochemically induced intramolecular proton transfer verified by electrochemical and spectroelectrochemical measurements. In the second part of this thesis the synthesis and characterisation of mononuclear and dinuclear 0,N coordinated Ru(II) complexes to hydroquinonepyrazole and phenolpyridyltriazole were described. The mononuclear complexes exhibit intense, broad range, visible absorbances, with Xmax tailing to 800 nm, they are photostable, luminescent and electroactive. Luminescence in complexes bound via 0,N are normally rare. The dinuclear 0,N coordinated complexes produced stable mixed valence states. These mixed valence states exhibit class II behaviour, i.e. weakly coupled, electronic communication between the metal centres. This interaction is particularly weak in the complex bridged by the phenolpyridyltriazole, which shows an intervalence transition of unusually high energy. Most interestingly, this complex, which is luminescent in the (II)-(II) state exhibits increased luminescence in the mixed valence state, whereby it appeared that the unoxidised N,N coordinated side of this complex became isolated from the Ru(III)0,N side of the complex in the excited state. Finally, a novel synthesis for the deuteration of bipyridyl was described, this synthesis is a one pot, high yield reaction, that was considerably easier than that available in current literature. The properties of complexes containing deuterated bpy are described and the value of employing deuterat ion as a means of ascertaining the position of the LUMO was discussed.

An eye lens is constantly exposed to the solar UV radiation, which is considered the most important external source of age-related changes to eye lens constituents. The accumulation of modifications of proteins and lipids with age can eventually lead to the development of progressive lens opacifications, such as cataracts. Though the impact of solar UV radiation on the structure and function of proteins is actively studied, little is known about the effect of photodamage on plasma membranes of lens cells. In this work we exploit Fluorescence Lifetime Imaging Microscopy (FLIM), together with viscosity-sensitive fluorophores termed molecular rotors, to study the changes in viscosity of plasma membranes of porcine eye lens resulting from two different types of photodamage: Type I (electron transfer) and Type II (singlet oxygen) reactions. We demonstrate that these two types of photodamage result in clearly distinct changes in viscosity - a decrease in the case of Type I damage and an increase in the case of Type II processes. Finally, to simulate age-related changes that occur in vivo, we expose an intact eye lens to UV-A light under anaerobic conditions. The observed decrease in viscosity within plasma membranes is consistent with the ability of eye lens constituents to sensitize Type I photodamage under natural irradiation conditions. These changes are likely to alter the transport of metabolites and predispose the whole tissue to the development of pathological processes such as cataracts.