Phthalocyanines in Photobiology and Their Medical Applications

Synthesis, Spectral, and Fluorescence Studies of Fluorophenyl Methoxy Substituted Nickel Phthalocyanine Complex

The synthesis, characterization, spectral, fluorescence properties of bis(4-fluorophenyl)-methoxy substituted nickel phthalocyanine were reported for the first time. The new compound has been characterized by elemental analysis, UV-Vis, FT-IR, 1H-NMR and mass spectra. The aggregation behaviour of this compound was investigated in the different solvent and concentrations of in CHCl3. Phthalocyanine complex did not show any aggregations. The fluorescent properties of the compound in five different solvents such as CHCl3 CH2Cl2 THF, DMF, DMSO were explained. Phthalocyanine complex gave the highest fluorescence quantum yield in CHCl3 and the lowest fluorescence quantum yield in DMSO.

Structure and electrochemical properties of carbon nanostructures derived from nickel(II) and iron(II) phthalocyanines

Mesoporous carbons containing up to 3.6 at.% N and 4.4 at.% O and exhibiting graphitic character have been prepared from Ni(II) and Fe(II) phthalocyanines by direct pyrolysis or by HTC + pyrolysis, and subsequently applied as supercapacitor materials. No mesoporous templates or doping post-treatments were used, and the catalytic effect of Ni(II) and Fe(II), naturally present in the precursor molecules, allowed obtaining graphitic carbons at temperatures ≤ 900 °C. Metals were encapsulated in the core of onion-like structures with no contact with the electrolyte, so that electrodes were prevented from degradation during device operation. The materials exhibited high rate capabilities up to 1 V s^-1, higher interfacial capacitances than a wide variety of materials possessing higher surface areas, and high capacitance retentions up to 99% at 5 A g^-1 current density throughout 10 000 charge-discharge cycles. The electrochemical performances of the phthalocyanine-derived carbons are due to their graphitic character and to the pseudocapacitance contribution of the surface groups through Faradaic reactions. This work opens a new way to obtain carbon materials from a great family of metal phthalocyanines, since the central metal and the radicals of the latter can be varied to tune the carbon properties for specific applications.

Synthesis, characterization of new phthalocyanines and investigation of photophysical, photochemical properties and theoretical studies

This work describes the synthesis, spectral, aggregation and fluorescence properties of bis 4-[(4-tert-butylbenzyl)oxy substituted metal free (2), magnesium (3), zinc (4) and nickel (5) phthalocyanines. The syntheses of the novel compounds were confirmed by FT-IR, UV-vis, mass and NMR spectroscopy techniques, as well as elemental analysis. The effects of the nature of the central metal on the photophysical parameters of the phthalocyanine complexes are reported in this study. The photochemical properties (singlet oxygen quantum yields and photodegradation quantum yields) and photophysical properties (fluorescence behavior and fluorescence quantum yield) of the complexes were reported in different solutions (dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) and tetrahydrofuran (THF)). However, energy minimized structure, vibrational frequency, molecular orbital levels and electronic absorption spectra were obtained by DFT calculations which supported the experimental results.

Singlet oxygen quantum yields and photostability of planar binuclear phthalocyanines

The singlet oxygen ([Formula: see text]O[Formula: see text] quantum yield of the near-infrared absorbing ([Formula: see text] [Formula: see text] 839 nm) planar [Formula: see text]-conjugated binuclear zinc phthalocyanine (ZnPc) was measured and compared to the [Formula: see text]O[Formula: see text] quantum yields of the mononuclear and the planar binuclear phthalocyanine without [Formula: see text]-conjugation between Pc rings. In addition, the photooxidative stability of the [Formula: see text]-conjugated binuclear Pc was determined and compared to the stabilities of the mononuclear ZnPc and the known near-infrared photosensitizer, zinc tetra-tert-butylnaphthalocyanine ([Formula: see text] 761 nm). The results are explained by DFT calculations and cyclic voltammetry.

Synthesis, spectroscopic, and cellular properties of α-pegylated cis-A2B2- and A3B-types ZnPcs

A series of pegylated cis-A₂B₂- or A₃B-type ZnPcs, substituted on the α-positions with tri(ethylene glycol) and hydroxyl groups, were synthesized from a new bis-phthalonitrile. A clamshell-type bis-phthalocyanine was also obtained as a byproduct. The hydroxyl group of one ZnPc was alkylated with 3-dimethylaminopropyl chloride to afford a pegylated ZnPc functionalized with an amine group. All mononuclear ZnPcs were soluble in polar organic solvents, showed intense Q absorptions in DMF, and had fluorescence quantum yields in the range 0.10-0.23. The clamshell-type bis-phthalocyanine adopts mainly open shell conformations in DMF, and closed clamshell conformations in chloroform. All ZnPcs were highly phototoxic to human carcinoma HEp2 cells, particularly the amino-ZnPc mainly protonated under physiological conditions, which showed the highest phototoxicity (IC₅₀ = 0.5 μM at 1.5 J/cm²) and dark cytotoxicity (IC₅₀ = 22 μM), in part due to its high cellular uptake. The ZnPcs localized in multiple organelles, including mitochondria, lysosomes, Golgi and ER.

Synthesis of water-soluble cobalt and zinc phthalocyanines with cationic substituents

Hexadecasubstituted CoPc and ZnPc containing different number of N-methylpyridiniumoxy groups and chlorine atoms were synthesized. It was shown that increasing number of cationic groups leads both to increased solubility of complexes in dipolar aprotic organic solvents and in water, and to increased contribution of monomeric form in aggregation equilibrium in water up full disaggregation.

Axial coordination of zinc and silicon phthalocyanines to silver and gold nanoparticles: an investigation of their photophysicochemical and antimicrobial behavior

This work reports on the axial coordination of zinc phthalocyanine and bis-(1,6-hexanedithiol) silicon phthalocyanine to silver and gold nanoparticles. Red shifting of absorption spectra of the phthalocyanine complexes was observed after conjugation with the nanoparticles. An improvement in the photophysicochemical behavior and antimicrobial activity was achieved in the presence of metal nanoparticles for both complexes. A decrease in triplet lifetimes was observed for all the phthalocyanine metal nanoparticle conjugates. The Zn phthalocyanine complex gave the highest triplet and singlet oxygen quantum yield in the presence of gold nanoparticles. On the other hand, the bacterial inhibition was found to be best for the Si phthalocyanine derivative in the presence of nanoparticles compared to the Zn phthalocyanine counterpart. The highest antimicrobial activity was achieved for both conjugates against B. subtilis compared to S. aureaus both in the dark and under illumination with light.

Synthesis, spectral properties, cation-induced dimerization and photochemical stability of tetra-(15-crown-5)-phthalocyaninato indium(III)

The novel 2,3,9,10,16,17,23,24-tetra-(15-crown-5)phthalocyaninato indium(III) hydroxide [(15 C 5)4 Pc ] In ( OH )(I) was obtained by direct interaction of tetra-(15-crown-5)-phthalocyanine with indium acetylacetonate with 90% yield. The set of UV-vis, 1 H NMR and MALDI-TOF spectroscopy data allowed the unambiguous interpretation of complex structure. It was shown that the developed synthetic approach can be also used for synthesis of indium(III) 2,3,9,10,16,17,23,24-octabutoxyphthalocyanine [( BuO )8 Pc ] In ( OH )(II). Photophysical characteristics (fluorescence and singlet oxygen quantum yields) of I were established. The photochemical stability of I was compared with tetra-(15-crown-5)-phthalocyanine H 2[(15 C 5)4 Pc ] and aluminum(III) complex [(15 C 5)4 Pc ] Al ( OH ). It was found that cation-induced formation of cofacial dimers [2I × 4MX] ( M = K +, Rb +, X = CO 32-, OPic -, OPiv -, SO 42-, ClO 4-, Br -) resulted in significant enhancement of complex photostability.

Synthesis and biological investigations of a ZnPc-antiCEA bioconjugate for imaging of colorectal cancer

Two zinc(II) phthalocyanines (ZnPcs) were conjugated with a monoclonal antibody (MAb) directed against carcinoembryonic antigen (CEA), using an in situ activated carboxylic acid on the ZnPcs. The bioconjugate with the highest ZnPc/MAb ratio of 3 was investigated in vitro for its ability to target and fluorescently label human colorectal HT-29 cells. The ZnPc-CEA MAb 2 was observed to efficiently target HT-29 cells, about 37 times more than unconjugated ZnPc. Furthermore, in the presence of a 4-fold excess of unlabelled anti-CEA antibody, the fluorescence signal of 2 was reduced by ~90% showing that the targeting is CEA-mediated. These studies further confirm the high specificity of Pc-antibody conjugates for antigens over-expressed on tumor cells and warrant further investigations of these immunoconjugates and their derivatives for imaging of colorectal cancer.

The synthesis, photophysical and dielectric properties of ball-type dinuclear zinc phthalocyanine

The synthesis of ball-type dinuclear Zn(II) phthalocyanine containing four 4,4′-(9H-fluorene-9,9-diyl)diphenol substituents at the non-peripheral position is presented. The structure of the synthesized compound was characterized using elemental analyzes, and UV-vis, FT-IR,1H NMR and mass spectroscopies. The ΦFvalue was 0.16 and ΦTvalue was 0.72. The complex showed reasonably long triplet lifetimes with τT7210 μs in DMSO. The frequency and temperature dependence of the dielectric properties of ZnPc were also investigated in the frequency range of 40–105Hz and in the temperature range of 300–440 °K. It has been observed that both dielectric constant ε′ and dielectric loss ε″ decrease with the rise in frequency as they increase with the rise in temperature. The decrease in ε′ with increasing frequency is attributed to the fact that as the frequency increases, the polarizability contribution from orientation sources decreases and finally disappears.

A comparative study on photophysical and photochemical properties of zinc phthalocyanines with different molecular symmetries

The five possible non-peripherally substituted zinc(II) phthalocyanines with different molecular symmetries (Pc1–Pc5) were synthesized from statistical condensation of the phthalonitrile derivatives (A and B). 2-[2-(2-ethoxyethoxy)ethoxy]-1-[2-((2-ethoxyethoxy)-ethoxy)ethoxymethyl]ethyloxy and 2′-[(tert-butoxycarbonyl)amino]ethoxy groups were used as substituents. The structures of the new compounds were characterized using elemental analysis and spectroscopic data including IR, 1H and 13C NMR, electronic absorption and mass spectra. The photophysical and photochemical properties of these new compounds were investigated in DMSO. The effect of the molecular symmetry of phthalocyanine molecules on the photophysical and photochemical properties was compared in this study.

Protonation of some non-transition metal phthalocyanines — spectral and photophysicochemical consequences

The photophysics and photochemistry of phthalocyanine complexes of magnesium (MgPc), aluminum chloride (ClAlPc) and zinc (ZnPc) are studied in N,N′-dimethylformamide (DMF). The values obtained for the photophysical and photochemical parameters are normal for simple metallophthalocyanine (MPc) complexes. Protonation of the azomethine bridges reduced the photoactivities of the complexes considerably; however the excited triplet states of the protonated species are more stable towards ground state oxygen. The interaction of the non-protonated MPcs with ground state oxygen is shown to be diffusion-assisted, with bimolecular rate constant values of the order of 1010 M-1.s-1. MgPc could not be protonated; it was easily demetalated by the protonating acid. The kinetics of the demetalation yielded the rate equation: Rate = 0.1[MgPc][H+]2/3

Photophysics and photochemistry of octaglucosylated zinc phthalocyanine derivatives

The ground state electronic absorption spectra, photophysics and photochemistry of amphiphilic octaglucosylated zinc phthalocyanines containing oxygen or sulfur bridges are presented. Triplet quantum yield values for the two dyes (in DMF and DMSO) vary between 0.71 and 0.84, while singlet quantum yield values lie between 0.63 and 0.75. Fluorescence lifetimes were determined experimentally by time correlated single photon counting and semi-empirically by fluorescence quenching techniques; and values from both methods were within the same range. Kinetic data were obtained for the quenching of the triplet state of the phthalocyanines by ground state molecular oxygen; the bimolecular collisional quenching rate constant range between 2.35 × 108 and 1.13 × 109 M-1.s-1. These values suggest that triplet states of the dyes are effectively quenched by ground molecular oxygen.

Synthesis and crystal structure of a novel phthalocyanine-calixarene conjugate

We report the synthesis and crystal structure of a novel phthalocyanine-calixarene conjugate (Pc-Calix) derived from a calixarene-based phthalonitrile (Pn-Calix). Crystal structures confirm the retention of the full cone configuration of the calixarene unit, which is thus suitable for the binding of appropriate chemical species. This new conjugate may find application as a molecular sensor in which the calixarene acts as the binding site and the perturbations of the optical properties of the phthalocyanine reports the presence of the binding species.

Electrochemical, spectroscopic and microscopic studies of new manganese phthalocyanine complexes in solution and as self-assembled monolayers on gold

Four new manganese(III) phthalocyanines (3a–d), octasubstituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups, respectively, were synthesized. Their specific electrochemical, spectroscopic and microscopic properties in solution and as self-assembled monolayers on gold were characterized. The UV-vis spectra confirmed red-shifted Q bands for all the complexes, due to the effect of the central metal and the electron-donating substituents. Three redox couples were visible during cyclic voltammetry studies for the four complexes, and spectroelectrochemistry confirmed the couples as corresponding to MnIIIPc-2/MnIIPc-2 (II) (metal reduction), MnIIPc-2/MnIIPc-3 (III) (ring reduction) and MnIIIPc-1/MnIIIPc-2 (I) (ring oxidation). Electrochemistry was also used to determine the blocking characteristics of the MnPc self-assembled monolayers on gold, which proved to be highly dependent on the type of substituent. Other methods of characterization included Raman spectroscopy, atomic force and scanning electrochemical microscopy analyses of the SAMs.

Synthesis of charged triazatetrabenzcorroles, phthalocyanines and tetrapyridylporphyrin, and their activities in the co-sensitized photooxidation of 2-mercaptoethanol

Water soluble zwitterionic, as well as cationic and anionic triazatetrabenzcorroles (TBC), phthalocyanines (Pc) and a porphyrin (P) were synthesized and their sensitizer properties investigated. Monomerization of the sensitizers, including their mixtures, in the presence of a detergent was used as a basis for studying the fundamental effect of co-sensitization upon a known model reaction, viz. the photooxidation of 2-mercaptoethanol in aqueous alkaline solutions. Compared to single-component sensitizers, a remarkable improvement of the photocatalytic activity is observed in the case of co-sensitization employing molecules that absorb in different Q and Soret regions.

Synthesis and photobiological properties of novel silicon(IV) phthalocyanines axially modified by paracetamol and 4-hydroxyphenylacetamide

Two novel axial-disubstituted silicon(IV) phthalocyanines (compounds 1 and 2) have been prepared by introducing paracetamol (a common antipyretic analgesic) or its isomer 4-hydroxyphenylacetamide at the axial positions of silicon(IV) phthalocyanine, respectively. Their photophysical and biological properties have been examined. Both compounds are highly soluble and exhibit very similar absorption spectra in N, N-dimethylformamide, which is typical for non-aggregated phthalocyanines. Both compounds are photocytotoxic against HT29 human colon adenocarcinoma cells. Compound 2 shows a very high in vitro photodynamic activity, with the IC50 value down to 15 nM. In contrast, compound 1 exhibits a much lower in vitro photodynamic activity toward HT29 cells, which can be attributed to its higher aggregating trend in the biological medium and lower singlet oxygen quantum yield.

Synthesis and spectral properties of a dihydroxo(phthalocyaninato)antimony(V) complex

The title complex cation, [ Sb ( pc )( OH )2]+, (pc = phthalocyaninate, C 32 H 16 N 82-) has been prepared by oxidizing [ Sb ( pc )] I 3 with tert-butyl perbenzoate and isolated as hexafluorophosphate and triflate salts. These salts are relatively well-soluble in polar solvents (e.g. CH 2 Cl 2, acetonitrile, acetone) without detectable aggregation. In particular, they dissolve relatively well in ethanol and methanol in which [ Sb ( pc ) Br 2]+ or [ Sb ( pc ) Cl 2]+ salts are poorly soluble whereas they have extremely low solubility in 1-chloronaphthalene and CHCl 3, unlike the bromo or chloro analogs. The spectral properties of [ Sb ( pc )( OH )2]+ have been investigated by optical absorption and magnetic circular dichroism spectroscopy. Although its Q band tends to appear at a longer wavelength in a solvent with a larger refractive index, as is the case for its Br and Cl analogs, the Q band positions in donor solvents deviate considerably from linear correlation between Onsager's solvent polarity function. In the Soret band region, spectra of [ Sb ( pc )( OH )2]+ are different in CH 2 Cl 2 and acetonitrile, particularly around the B1/B2 bands, unlike the bromo and chloro analogs. The solvent dependence of absorption spectra and the difference in solubility suggests that the presence of the axial hydroxyl groups endows the phthalocyanine macrocycle with considerable hydrophilicity. It also suggests that there are some specific chemical interactions between the axial hydroxyl groups and the surrounding donor solvent molecules.

The key role of peripheral substituents in the chemistry of phthalocyanines and their analogs

The preparation and optical properties of peripherally substituted phthalocyanines and their analogs (i.e. naphthalocyanines, anthracyanines, aza-analogs of phthalocyanines, and tetraazaporphyrins) have been widely discussed. This review highlights methodologies that have been published in poorly known and mostly unavailable Russian journals.

Synthesis and Photophysical Properties of Annulated Dinuclear and Trinuclear Phthalocyanines

Metal-free mononuclear, dinuclear and trinuclear phthalocyanines were prepared by a mixed cyclotetramerisation of a 1,2,4,5-tetracyanobenzene derivative and 4,5-bis(2,6-dimethylphenoxy)phthalonitrile. For the first time, a pi-electron-conjugated trinuclear phthalocyanine was synthesised with phthalocyanine units connected by common annulated benzene rings. The Q band of the trinuclear compound in solution occurs at lambda = 944 nm whereas those of the dinuclear and mononuclear compounds are at lambda = 853/830 and 701/664 nm, respectively. Fluorescence quantum yields, fluorescence lifetimes and singlet-oxygen quantum yields of the compounds were determined.