Synthesis,characteristics and photochemical studies of novel porphyrazines possessing peripheral 2,5-dimethylpyrrol-1-yl and dimethylamino groups

The synthesis and physicochemical properties of novel porphyrazines possessing an alternate system of two peripheral substituents, 2,5-dimethylpyrrol-1-yl and dimethylamino, are presented. All the macrocycles were subjected to HPLC purity studies. Spectroscopic studies of magnesium(II) porphyrazine encompassed steady state absorption, emission measurements, including fluorescence decays, transient absorption spectra, and thermoluminescence. Additionally, magnesium(II) porphyrazine was found to be a moderate photosensitizer with singlet oxygen generation values of 0.12 and 0.14 in DMF and DMSO, respectively. Comparison of the quantum yields of singlet oxygen generation before and after deoxygenation showed that the photodynamic effect of magnesium(II) porphyrazine is governed by the photosensitization mechanism II. Magnesium(II) and manganese(III) porphyrazines were characterized using X-ray crystallography.     

A novel lutetium(III) acetate phthalocyanine directly substituted with N,N’-dimethylaminophenyl groups via CC bonds and its water-soluble derivative for photodynamic therapy

In this study, the novel 4-(N,N′-dimethylamino)phenyl substituted lutetium(III) acetate phthalocyanine (2) and its quaternized derivative (3) were synthesized via a Suzuki-Miyaura coupling reaction between tetrakis(iodo) lutetium(III)acetate phthalocyanine (1) and 4-(N,N-dimethylamino)phenylboronic acid, and subsequent quaternization using dimethyl sulfate, respectively. The obtained phthalocyanine 3 exhibited excellent solubility in water which is important for photodynamic therapy applications. Photophysical properties such as fluorescence quantum yield and fluorescence lifetime, and photochemical properties such as singlet oxygen generation and photostability were investigated to determine their suitability for photodynamic therapy. The lutetium(III) phthalocyanines, especially quaternized derivative 3, showed promising properties as potential photosensitizers for the treatment of cancer, producing higher singlet oxygen (Φ_Δ = 0.59) than motexafin lutetium (Φ_Δ = 0.31) which is a clinically used lutetium texaphyrin photosensitizer.     

New soluble methylendioxy-phenoxy-substituted zinc phthalocyanine derivatives: Synthesis, photophysical and photochemical studies

The syntheses of new three phthalonitriles (1, 2 and 3), together with photophysical and photochemical properties of the resulting peripherally and non-peripherally tetrakis- and octakis 3,4-(methylendioxy)-phenoxy-substituted zinc phthalocyanines (4, 5 and 6) are described for the first time. Complexes 4, 5 and 6 have been synthesized and characterized by elemental analysis, IR, ¹H NMR spectroscopy, electronic spectroscopy and mass spectra. Complexes 4, 5 and 6 have good solubility in organic solvents such as CHCl₃, DCM, DMSO, DMF, THF and toluene and are mainly not aggregated (except for complex 6 in DMSO) within a wide concentration range. General trends are described for singlet oxygen, photodegradation, fluorescence quantum yields, triplet quantum yields and triplet life times of these complexes in DMSO and toluene. Complex 4 has higher singlet oxygen quantum yields, fluorescence quantum yields, triplet quantum yields and triplet life times than complexes 5 and 6. The effect of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (4, 5 and 6) are also reported.     

Comparative studies of photophysical and photochemical properties of solketal substituted platinum(II) and zinc(II) phthalocyanine sets

A complete set of platinum(II) solketal substituted phthalocyanines has been synthesized and characterized. To evaluate their potential as Type II photosensitizers for photodynamic therapy, comparative studies of their photophysical and photochemical properties with analogous zinc(II) series have been achieved: electronic absorption, fluorescence quantum yields, lifetimes, and fluorescence quenching by benzoquinone, as well as singlet oxygen generation and photodegradation. It appears that platinum(II) phthalocyanines are worth being used as Type II photosensitizers, as they exhibit good singlet oxygen generation and appropriate photodegradation.     

Synthesis, photophysical and photochemical properties of poly(oxyethylene)-substituted zinc phthalocyanines

The synthesis, photophysical and photochemical properties of the tetra- and octa-poly(oxyethylene)substituted zinc (II) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, triplet state and fluorescence quantum yields, and triplet and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The effects of the substituents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (3a, 5a and 6a) are also reported. The singlet oxygen quantum yields (Phi(Delta)), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.60 to 0.72. Thus, these complexes show potential as Type II photosensitizers. The fluorescence of the complexes was quenched by benzoquinone (BQ).     

Solvent and central metal effects on the photophysical and photochemical properties of 4-benzyloxybenzoxy substituted phthalocyanines

The synthesis and characterization of new peripherally tetra-4-benzyloxybenzoxy substituted metal-free, zinc and lead phthalocyanines are described for the first time in this study. The influence of various organic solvents and the nature of the central metal ion on the spectroscopic, photophysical and photochemical properties has been investigated. General trends are described for photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds in different solvents. Photophysical and photochemical properties of phthalocyanine compounds are very useful for photodynamic therapy applications. Especially high singlet oxygen quantum yields are very important for Type II mechanism. The studied phthalocyanine compounds showed good singlet oxygen generation and these compounds show potential as Type II photosensitizers. The fluorescences of the studied compounds are effectively quenched by 1,4-benzoquinone in different solvents.     

Synthesis, photophysical and photochemical properties of substituted zinc phthalocyanines

The synthesis, photophysical and photochemical properties of the 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}oxy) and 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}thio) zinc(ii) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, (1)H and (13)C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, fluorescence and triplet excited state quantum yields, and triplet state and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The fluorescence of the complexes was quenched by benzoquinone (BQ). The effects of the substitution on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (6, 7 and 8) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The substituted Zn(II) phthalocyanines showed high triplet and singlet oxygen quantum yields. High singlet oxygen quantum yields are very important for Type II mechanism. Thus, these complexes show potential as Type II photosensitizers.     

Synthesis,photophysical and photochemical properties of tetra- and octa-substituted gallium and indium phthalocyanines

The synthesis, photophysical and photochemical properties of the tetra- and octa-[4-(benzyloxyphenoxy)] substituted gallium(III) and indium(III) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, ¹H NMR spectroscopy and electronic spectroscopy. General trends are described for quantum yields of photodegredation, fluorescence quantum yields and lifetimes, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulfoxide (DMSO). Substituted indium phthalocyanine complexes (7b–9b) showed much higher quantum yields of triplet state and shorter triplet lifetimes, compared to the substituted GaPc derivatives due to enhanced intersystem crossing (ISC) in the former. The gallium and indium phthalocyanine complexes showed phototransformation during laser irradiation due to ring reduction. The singlet oxygen quantum yields (Φ_Δ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.51 to 0.94. Thus, these complexes show potential as photodynamic therapy of cancer.     

Photolysis of methyl-parathion thin films: Products,kinetics and quantum yields under different atmospheric conditions

The present study focuses on the photodegradation of methyl-parathion thin films, an organophosphate insecticide, under different atmospheric conditions. The latter include nitrogenated, oxygenated and ozonated atmospheres, under low and high relative humidity conditions. Addition of oxygen to the atmospheric mixture did not seem to affect the reaction rates and quantum yields. Relative humidity affect was minor, with a small enhancement in reaction rate under 254 nm radiation. The addition of ozone (to either dry or humid atmosphere), at all concentrations tested, largely enhanced degradation rates. In the absence of ozone, the obtained quantum yields for photolysis of methyl-parathion thin films under 254 and 313 nm were 0.024 ± 0.007 and 0.012 ± 0.005, respectively. These values are higher than the values previously reported for solutions of methanol and water. Although the presence of molecular oxygen and water vapors did not seem to affect much the reaction rates, it did have a certain effect on the resulted products. More polar products were obtained under oxygenated and ozonated atmospheres, as well as dimers under ozone conditions. The reaction on thin films has yielded more toxic products than usually found in solutions, adding alkylphosphate esters in addition to the oxons formed normally.     

Photophysical and photochemical studies of thifensulfuron-methyl herbicide in aqueous solution

The photophysical and photochemical studies of a sulfonylurea herbicide, thifensulfuron-methyl (THM), have been investigated in a buffered aqueous solution. In the first part, the influence of pH on the spectroscopic properties was studied. This allowed the determination of the ground and excited state acidity constants, pK_a = 4 and 4.4, respectively, thus exhibiting the potential existence of a photoinduced protonation in the singlet state. In the second part, the photolysis kinetics was studied at different pH and varying oxygen concentrations, using an HPK 125 W lamp and followed up by the identification of photoproducts formed under continuous photo-irradiation. The kinetics results suggest that the photolysis process is faster in acidic (k = 3 × 10^?4 s^?1) than in basic medium (k = 9.8 × 10^?5 s^?1). The photolysis products were identified by high performance liquid chromatography HPLC-DAD, HPLC–MS and HPLC–MS–MS. In order to obtain a better understanding of the photodegradation mechanism, a laser flash photolysis study was performed. By comparing the quenching rate constant (k_q = 9.64 × 10⁸ mol^?1 l s^?1) obtained from triplet state quenching by molecular oxygen and from the Stern–Volmer relation (k_q = 0.41 × 10⁸ mol^?1 l s^?1), the role of the singlet state in the photodegradation process was demonstrated. The photoproducts originating from both singlet and triplet excited states have been identified and hypothetical photodegradation pathways of the thifensulfuron-methyl in aqueous solution are proposed.     

Photophysicochemical and fluorescence quenching studies of benzyloxyphenoxy-substituted zinc phthalocyanines

Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetrakis- and octakis(4-benzyloxyphenoxy)-substituted zinc phthalocyanines (1, 2 and 3). General trends are described for photodegradation, and fluorescence quantum yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulphoxide (DMSO) and toluene. The fluorescence of the complexes is quenched by benzoquinone (BQ), and fluorescence quenching properties are investigated in DMSO and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2 and 3) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications.     

Synthesis and characterization of a new soluble metal-free and metallophthalocyanines bearing biphenyl-4-yl methoxy groups

The synthesis and characterization of peripherally tetra-biphenyl-4-yl-methoxy substituted metal-free (4), Ni(II) (5), Cu(II) (6), Zn(II) (7), Co(II) (8) and Pb(II) (9) phthalocyanine derivatives are reported. These new phthalocyanine derivatives show the enhanced solubility in organic solvents and they have been characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–vis, mass spectral data, elemental analysis and thermal analysis methods (TG/DTA). The photophysical (fluorescence quantum yield and lifetime) and photochemical (singlet oxygen generation and photodegradation quantum yield) properties of tetra-biphenyl-4-yl-methoxy substituted zinc (II) phthalocyanine derivative (7) are also investigated. The fluorescence of this phthalocyanine derivative (7) is effectively quenched by addition of 1,4-benzoquinone (BQ).     

Synthesis,characterization, and determination of photophysicochemical properties of peripheral and nonperipheral tetra‐7‐oxy‐3,4‐dimethylcoumarin substituted zinc,indium phthalocyanines

The photochemical and photophysical properties of peripheral and nonperipheral zinc and indium phthalocyanines containing 7‐oxy‐3,4‐dimethylcoumarin synthesized were investigated in this study. 7‐Hydroxy‐3,4‐dimethylcoumarin ( 1 ) was synthesized via Pechmann condensation reaction and then the phthalonitrile derivatives [4‐(7‐oxy‐3,4‐dimethylcoumarino)phthalonitrile ( 2 ) and 3‐(7‐oxy‐3,4‐dimethylcoumarino)phthalonitrile ( 3 )] were synthesized by nucleophilic aromatic substitution. Phthalocyanine compounds containing coumarin units on peripheral ( 4 and 5 ) and nonperipheral ( 6 and 7 ) positions were prepared via cyclotetramerization of phthalonitrile compounds. All compounds' characterizations were performed by spectroscopic methods and elemental analysis. The phthalocyanine derivatives' ( 4–7 ) photochemical and photophysical properties were studied in DMF. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yields) properties of these novel phthalocyanines ( 4 – 7 ) were studied in DMF. They produced good singlet oxygen (e.g., Φ_Δ = 0.93 for 7 ) and showed appropriate photodegradation (in the order of 10^?5), which is very important for photodynamic therapy applications.     

Novel gallium(III) phthalocyanine derivatives – Synthesis,photophysics and photochemistry

The syntheses of gallium(III) chloride phthalocyanine {(Cl)GaPc}, octaphenoxyphthalocyaninato gallium(III) chloride {(Cl)GaOPPc} and octakis(4-tert-butylphenoxy)phthalocyaninato gallium(III) chloride {(Cl)GaOTBPPc}; as well as their photophysical and photochemical parameters are hereby presented. Fluorescence quantum yields do not vary much among the three metallophthalocyanines (MPcs); therefore it was concluded that the effect of the substituents is not significant amongst (Cl)GaPc, (Cl)GaOPPc and (Cl)GaOTBPPc. Solvents effects, however, had an effect on the results. Triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. We have also reported photodegradation and singlet oxygen quantum yields. There was no clear correlation between the later parameters. It was, however, established that the three MPcs were stable.     

Synthesis, photophysical and photochemical properties of aryloxy tetra-substituted gallium and indium phthalocyanine derivatives

The synthesis, photophysical and photochemical properties of the tetra-substituted aryloxy gallium(III) and indium(III) phthalocyanines are reported for the first time. General trends are described for photodegradation, singlet oxygen, fluorescence, and triplet quantum yields and triplet lifetimes of these compounds. The introduction of phenoxy and tert-butylphenoxy substituents on the ring resulted in lowering of fluorescence quantum yields and lifetimes, and triplet quantum yields, and an increase of k_IC, k_ISC, and k_F. Photoreduction of the complexes was observed during laser flash photolysis. The singlet oxygen quantum yields (Φ_Δ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.41 to 0.91. Thus, these complexes show potential as Type II photosensitizers.     

Synthesis, characterization and comparative studies on the photophysical and photochemical properties of metal-free and zinc(II) phthalocyanines with phenyloxyacetic acid functionalities

The synthesis and characterization of new peripherally and non-peripherally tetra-substituted metal-free and zinc(II) phthalocyanines with 2-, 3- and 4-phenyloxyacetic acid functionalities are described for the first time in this study. The new compounds have been characterized by elemental analysis, FT-IR, UV-Vis, MALDI-TOF and ¹H-NMR spectra. Photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds are studied in dimethylformamide (DMF). The influence of the substituent position on the phthalocyanine framework (non-peripherally or peripherally), central metal ion (metal-free or zinc) and the position of the COOH group (2-, 3- or 4-position on the phenyloxyacetic acid) on the spectroscopic, photophysical and photochemical properties have been investigated. Non-peripherally zinc(II) phthalocyanines (1b and 2b) and peripherally zinc(II) phthalocyanine (4b) gave good singlet oxygen quantum yields (Φ_Δ) (0.37, 0.39 and 0.38, respectively) which indicate the potential of the complexes as photosensitizers in applications of PDT.     

Photooxidation of phenol in aqueous nanodispersion of humic acid

Photooxidation of phenol sensitized by Aldrich humic acid (AHA) has been studied in an aqueous solution at neutral and basic pH. Solutions containing phenol and AHA of various concentrations were irradiated with monochromatic light at 253.7 nm or with polychromatic light within the wavelength range of 310–420 nm. The quantum yields of phenol photodegradation under these conditions were determined. At the wavelength of 253.7 nm direct degradation of phenol was much more effective than that sensitized by AHA. With polychromatic light the photooxidation was found to be strongly dependent on pH of aqueous solution and independent on AHA concentration.     

Low-dimensional quantum magnetic systems: Synthesis,structure and magnetic behavior of (2,5-dimethylpyrazine)copper(II) chloride and synthesis and magnetic behavior of bis(2,6-dimethylpyrazine)copper(II) chloride

The synthesis, X-ray structure and magnetic susceptibility of (2,5-dimethylpyrazine)copper(II) chloride (1), and the synthesis and magnetic susceptibility of (2,6-dimethylpyrazine)₂copper(II) chloride (2), are reported. Compound 1 crystallizes in the space group P2₁/c as a coordination polymer of Cu(II) ions bridged by 2,5-methylpyrazine. The resulting chains are magnetically linked via short chloride–chloride contacts. The magnetic susceptibility responds as a uniform Heisenberg chain (2J/k = −20(5) K) with a phase transition to three dimensional order near 5 K. Susceptibility data for compound 2 show that the compound is a linear chain coordination polymer with the copper ions linked by bihalide bridges. A fit to the model for a uniform Heisenberg chain yields 2J = −22.7(2) K.     

A combined laser flash photolysis,density functional theory and atoms in molecules study of the photochemical hydrogen abstraction by pyrene-4,5-dione

The photochemical hydrogen abstraction reaction of pyrene-4,5-dione (3) has been investigated by laser flash photolysis. Excitation (λ = 355 nm) of a degassed solution of 3 in acetonitrile resulted in the formation of a detectable transient with absorption maxima at 380 and 470 nm. This transient decays with a lifetime of around 4.8 μs and is quenched by oxygen. This transient is most probably a triplet state of 3. Addition of hydrogen donors, such as 2-propanol; 1,4-cyclohexadiene or 4-methoxyphenol led to the formation of a new transient with λ_max at 380, 500 nm and a broad absorption at 640 nm. This new transient slowly decays with second order kinetics and was assigned to the semiquinone radical obtained from the hydrogen abstraction reaction. Using DFT and AIM calculations the reactivity of 3 and 9,10-phenanthrenequinone (1) is best interpreted as a proton coupled electron transfer like mechanism for the hydrogen abstraction from 2-propanol.     

Sulfanyl Porphyrazines with Morpholinylethyl Periphery—Synthesis,Electrochemistry, and Photocatalytic Studies after Deposition on Titanium(IV) Oxide P25 Nanoparticles

The syntheses, spectral UV–Vis, NMR, and electrochemical as well as photocatalytic properties of novel magnesium(II) and zinc(II) symmetrical sulfanyl porphyrazines with 2-(morpholin-4-yl)ethylsulfanyl peripheral substituents are presented. Both porphyrazine derivatives were synthesized in cyclotetramerization reactions and subsequently embedded on the surface of commercially available P25 titanium(IV) oxide nanoparticles. The obtained macrocyclic compounds were broadly characterized by ESI MS spectrometry, 1D and 2D NMR techniques, UV–Vis spectroscopy, and subjected to electrochemical studies. Both hybrid materials, consisting of porphyrazine derivatives embedded on the titanium(IV) oxide nanoparticles’ surface, were characterized in terms of particle size and distribution. Next, they were subjected to photocatalytic studies with 1,3-diphenylisobenzofuran, a known singlet oxygen quencher. The applicability of the obtained hybrid material consisting of titanium(IV) oxide P25 nanoparticles and magnesium(II) porphyrazine derivative was assessed in photocatalytic studies with selected active pharmaceutical ingredients, such as diclofenac sodium salt and ibuprofen.