Insight into the effects of the anchoring groups on the photovoltaic performance of unsymmetrical phthalocyanine based dye-sensitized solar cells

Push-pull zinc phthalocyanine dyes bearing hexylsulfanyl moieties as electron donors and carboxyethynyl as mono- or di-anchoring groups have been designed, synthesized and tested as sensitizers in dye-sensitized solar cells (DSSCs). The effects of the anchoring groups on the optical, electrochemical and photovoltaic properties were investigated. The incorporation of a carboxyethynyl group in GT23 has a considerable effect on preventing dye aggregation due to its relatively non-planar structure. The mono-anchoring dye bearing a phenyl carboxyethynyl group, GT5, has a higher molar extinction coefficient and sufficient charge injection into the TiO2 conduction band. Therefore, GT5 achieved at least 90% higher power conversion efficiency than the di-anchoring dyes (GT31 and GT32). Time-dependent density functional theory (PBE0/6-31G(d,p)) was also used to calculate the electronic absorption spectra, which predicted very well the measured UV-Vis with an error of up to 0.11 eV for the Q bands and 0.3 eV for the B bands. The longest charge transfer bands are obtained in the visible light region and they correspond to a transfer phthalocyanine core → substituent with a carboxyethynyl group where the absorptions of GT32 (465 nm) and GT31 (461 nm) are red-shifted compared to GT23 (429 nm) and GT5 (441 nm). The interaction energy between the phthalocyanine and a cluster of anatase-TiO2 (H4Ti40O82) was calculated using density functional theory. For all phthalocyanines, the interaction favored is monodentate and corresponds to -O(OH)Ti(TiO2), where the stronger interaction occurs for GT32 (-2.11 eV) and GT31 (-2.25 eV). This study presents the molecular combination of the anchoring groups in zinc phthalocyanine sensitizers, which is one of the effective strategies for improving the performance of DSSCs.

Photodynamic inactivation of Staphylococcus aureus using tetraethylene glycol-substituted Zn(II) phthalocyanine

Methicillin resistant Staphylococcus aureus infections are increasing, especially in intensive care units. A new method for photodynamic inactivation (PDI) generates reactive oxygen species by photosensitization to kill bacteria. We investigated the PDI effect of tetraethylene glycol-substituted Zn(II) phthalocyanine (TEG-P) on S. aureus strains including two standards (ATCC 25923 and ATCC 43400) and 20 clinically isolated methicillin sensitive and 20 methicillin resistance strains. We also investigated three treated groups: 650 nm laser only, TEG-P only and TEG-P + laser, plus one control group. Treatments included 0.5, 1, 2, 4, 8, 16, 32 µg/ml concentrations of TEG-P. No suppression of bacterial growth was observed in the control, laser only and TEG-P only groups whether or not S. aureus was methicillin resistant. Bacterial growth was suppressed by 85% using 8 µg/ml TEG-P and completely suppressed by 32 µg/ml TEG-P in the TEG-P + laser group. A combination of TEG-P + laser treatment may be an alternative to conventional antibiotics for routine treatment of S. aureus infections, although further investigation of the effect at the tissue level is required.

In vivo phototoxic effects of a tetraethyleneglycol-substituted Zn phthalocyanine in tumor bearing rats at an enzymatic level

TEG-Pc, a Zn(II) phthalocyanine tetra substituted in non-peripheral position by tetraethylene glycol chains, proved to have good efficiency during in vitro photodynamic experiments. Its in vivo phototoxic effects have been investigated in tumor-bearing Wistar albino rats at an enzymatic level. The evolution of different oxidative markers are reviewed 6 h after the treatment.

A3B and ABAB aminophthalocyanines: Building blocks for dimeric and polymeric constructs

Mono or diamino phthalocyanines with A3B or crosswise ABAB substitution patterns have been synthesized and used as building blocks for the preparation of dimeric and polymeric phthalocyanines. For this, 4,5-di(dodecylsulfanyl) phthalonitrile was converted into 1,3-diimino-6,7-di-([Formula: see text]-dodecylsulfanyl)-isoiminoindoline and then reacted with 6-nitro-1,3,3-trichloroisoindoline. The nitro functions on the resulting inseparable mixture of A3B and ABAB phthalocyanines were reduced into amines by Na2S and the phthalocyanines could be chromatographically separated. Dimeric phthalocyanine was synthesized by the reaction of the mono-amino AB3 with sebacoyldichloride, and a poorly soluble linear polymeric material was obtained by reaction of the ABAB di-amino phthalocyanine with sebacoyl dichloride.

Peripherally carboxylic acid substituted asymmetric zinc(II) phthalocyanines: Synthesis and photophysicochemical properties

Four asymmetric Zn(II) phthalocyanines (Pc1–Pc4) bearing a carboxylic acid group in the peripheral position have been designed and synthesized to investigate the influence of the distance between COOH group and the phthalocyanine core on their photophysical and photochemical properties. The novel phthalocyanine complexes were characterized by [Formula: see text]H, [Formula: see text]C NMR, IR, and UV-vis spectroscopies, elemental analysis and matrix-assisted laser desorption ionization mass spectrometry (MALDI). The aggregation behavior, photophysical and photochemical properties such as fluorescence lifetime and quantum yields and singlet oxygen quantum yields of Pc1–Pc4 were explored in tetrahydrofuran (THF) to the determination of the potential use of these novel phthalocyanines as photosensitizers for different applications such as photovoltaic technologies and photodynamic therapy (PDT). Pc1–Pc4exhibited high singlet oxygen generation quantum yields (0.84, 0.66, 0.88 and 0.65, respectively). Fluorescence quantum yields could be obtained for Pc1, Pc2, Pc3 and Pc4 (0.13, 0.31, 0.10 and 0.25, respectively) in THF.

Phthalocyanine-based mesoporous organosilica nanoparticles: NIR photodynamic efficiency and siRNA photochemical internalization

Mesoporous organosilica nanoparticles (PHT-PMO) have been prepared from an octa-triethoxysilylated Zn phthalocyanine precursor and showed powerful NIR photodynamic efficiency and siRNA photochemical internalization.

Effect of new asymmetrical Zn(ii) phthalocyanines on the photovoltaic performance of a dye-sensitized solar cell

Theoretical and experimental examinations of novel asymmetric Zn(ii) phthalocyanine derivatives substituted with peripherally one carboxyl and six alkylsulfanyl groups have been successfully investigated from the point of view of DSSC performance.

Effect of the Substitution Pattern (Peripheral vs Non-Peripheral) on the Spectroscopic, Electrochemical, and Magnetic Properties of Octahexylsulfanyl Copper Phthalocyanines

In order to investigate the substitution position effect on the spectroscopic, electrochemical, and magnetic properties of copper phthalocyanines, a detailed structure-property analysis has been performed by examining two copper phthalocyanines that are octasubstituted by hexylsulfanyl chains respectively in the peripheral (Cu-P) and non-peripheral (Cu-NP) positions. Cu-NP showed a marked near-IR maximum absorption compared to Cu-P and, accordingly, a smaller HOMO-LUMO energy gap, calculated via the electrochemical results and simulations in the gas phase, as well as for Cu-NP from its crystallographic data. An electron-spin resonance (ESR) technique is used to extract the g values from the powder spectra that are taken at room temperature. The g values were determined to be g_∥ = 2.160 and g_⊥ = 2.045 for Cu-P and g_∥ = 2.150 and g_⊥ = 2.050 for Cu-NP. These values indicate that the paramagnetic copper center in both phthalocyanines has axial symmetry with a planar anisotropy ( g_∥ > g_⊥). The ESR spectra in solution could be obtained only for Cu-P. Curie law is used to fit the experimental data of the magnetic susceptibility versus temperature graphs, and the Curie constant ( C) and diamagnetic/temperature-independent paramagnetic (α) contributions are deduced as 0.37598 (0.39576) cm³·K/mol and -23 × 10^-5 (25 × 10^-5) cm³/mol respectively for Cu-P and Cu-NP. The room temperature magnetic moment value (1.70 μ_B) is close to the spin-only value (1.73 μ_B) for the peripheral complex, showing that there is no orbital contribution to μ_eff. In contrast, at room temperature, the value of the magnetic moment (1.77 μ_B) is above the spin-only value, showing an orbital contribution to the magnetic moment. Cu-NP's room temperature magnetic moment value is larger than the value for Cu-P, demonstrating that the orbital contribution to the magnetic moment depends upon the substituent position. The magnitudes of the effective magnetic moment values also support that both Cu-P and Cu-NP complexes have square-planar coordination. This result is consistent with the determined g values. The spin densities were determined experimentally, and the results suggest that the positions of the substituents affect these values (0.469 for Cu-P and 0.490 for Cu-NP).

Photophysical and photochemical properties of fluoroether-substituted zinc(II) and titanium(IV) phthalocyanines

The synthesis and characterization of novel zinc(II) (1a–4a) and oxo-titanium(IV) (1b–4b) phthalocyanine derivatives bearing 1H,1H-nona?uoro-3,6-dioxaheptan-1-ol groups are described for the first time. These phthalocyanines (1a–4a and 1b–4b) were characterized by elemental analysis and different spectroscopic techniques such as UV-vis, [Formula: see text]H NMR, FTIR and mass. Furthermore, the photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation) properties of these phthalocyanines were investigated in tetrahydrofuran (THF) solution. The influence of the number of the substituted groups (tetra or octa), position of the substituents (peripheral or non-peripheral) and central metal atom (zinc or titanium) on the photophysical and photochemical properties of these phthalocyanines were evaluated.

Synthesis and characterization of a new meso-tetra-dihydro benzocyclobutacenaphthylene free-base porphyrin

A meso-tetra-6b,10b-dihydrobenzo[j]cyclobut[a]acenaphthylene free-base porphyrin was synthesised and its photophysical, photochemical and electrochemical properties were compared with those of free-base meso-tetraphenylporphyrin. The frontier orbitals and the HOMO–LUMO energy gaps of both compounds were also determined. It was demonstrated that the meso6b,10b-Dihydrobenzo[j]cyclobut[a]acenaphthylene porphyrin retained the same properties as the tetraphenylporphyrin.

Zn phthalocyanine conjugation to H2-ul aptamer for HER2-targeted breast cancer photodynamic therapy: Design, optimization and properties

Tetrasulfonated Zn phthalocyanine was conjugated to a ssDNA aptamer moiety to produce a HER2 targeted photosensitizer. The tetraconjugate obtained was subjected to purification and the monoconjugate was successfully isolated, purified and characterized. This monoconjugate retained the ability to bind to HER2 as well as the potency to generate singlet oxygen.

Synthetic Access to a Pure Polyradical Architecture: Nucleophilic Insertion of Nitronyl Nitroxide on a Cyclotriphosphazene Scaffold

An optimized nucleophilic synthetic approach featuring mild conditions and microwave energy was utilized to circumvent the classical Ullman procedure and access a polynitronyl nitroxide radical easily and in pure form. The simultaneous controlled introduction of preformed nitronyl nitroxide radicals on a cyclotriphosphazene core leads to a novel polyphosphazene monomer which is suitable for both n- and a p-type redox-active material in organic rechargeable batteries as demonstrated by electrochemistry. Additionally, absorption spectra and square-wave voltammetry were utilized to quantify the number of nitronyl nitroxide radical units on the cyclotriphosphazene scaffold.

Porphyrin- or phthalocyanine-bridged silsesquioxane nanoparticles for two-photon photodynamic therapy or photoacoustic imaging

Porphyrin- or phthalocyanine-bridged silsesquioxane nanoparticles (BSPOR and BSPHT) were prepared. Their endocytosis in MCF-7 cancer cells was shown with two-photon excited fluorescence (TPEF) imaging. With two-photon excited photodynamic therapy (TPE-PDT), BSPOR was more phototoxic than BSPHT, which in contrast displayed a very high signal for photoacoustic imaging in mice.

Novel zinc phthalocyanine as a promising photosensitizer for photodynamic treatment of esophageal cancer

Photodynamic therapy (PDT) has gathered much attention in the field of cancer treatment and is increasingly used as an alternative solution for esophageal cancer therapy. However, there is a constant need for improving the effectiveness and tolerability of the applied photosensitizers (PS). Here, we propose tetra-triethyleneoxysulfonyl substituted zinc phthalocyanine (ZnPc) as a promising PS for photodynamic treatment of esophageal cancer. ZnPc-induced phototoxicity was studied in two human esophageal cancer cell lines: OE-33 (adenocarcinoma) and Kyse-140 (squamous cell carcinoma). In vitro studies focused on the uptake and intracellular distribution of the novel ZnPc as well as on its growth inhibitory potential, reactive oxygen species (ROS) formation and the induction of apoptosis. The chicken chorioallantoic membrane assay (CAM assay) and studies on native Wistar rats were employed to determine the antineoplastic and antiangiogenic activity of ZnPc-PDT as well as the tolerability and safety of non-photoactivated ZnPc in vivo. ZnPc was taken up by cancer cells in a dose- and time-dependent manner and showed a homogeneous cytoplasmic distribution. Photoactivation of ZnPc-loaded (1-10 µM) cells led to a dose-dependent growth inhibition of esophageal adenocarcinoma and squamous cell carcinoma cells of >90%. The antiproliferative effect was based on ROS-induced cytotoxicity and the induction of mitochondria-driven apoptosis. In vivo studies on esophageal tumor plaques grown on the CAM revealed pronounced antiangiogenic and antineoplastic effects. ZnPc-PDT caused long-lasting changes in the vascular architecture and a marked reduction of tumor feeding blood vessels. Animal studies confirmed the good tolerability and systemic safety of ZnPc, as no changes in immunological, behavioral and organic parameters could be detected upon treatment with the non-photoactivated ZnPc. Our findings show the extraordinary photoactive potential of the novel ZnPc as a photosensitizer for PDT of esophageal cancer.

Assessment of the relevance of GaPc substituted with azido-polyethylene glycol chains for photodynamic therapy. Design, synthetic strategy, fluorescence, singlet oxygen generation, and pH-dependent spectroscopic behaviour

New synthetic route and PDT potential of symmetrically and asymmetrically substituted Ga(iii)Pcs with terminal azides.

Subtle variations of the behavior of a silylated tetraethylene glycol-substituted Zn phthalocyanine towards acids

An organosoluble phthalocyanine substituted by four silylated tetraethyleneglycol chains was designed. This phthalocyanine become water-soluble after acid-promoted removal of the TBDMS moieties (which does not occur in acetonitrile), and is therefore a naked-eye observation system of acid aqueous media. Fluoride anion sensitivity based on the same principle proved unfortunately unsuccessful.

Synthesis and Straightforward Quantification Methods of Imino Nitroxide-Based Hexaradical Architecture on a Cyclotriphosphazene Scaffold

The synthesis of a homogeneous neutral hexaradical architecture consisting of six imino nitroxide radical moieties covalently bonded on a cyclotriphosphazene scaffold was reported. The synthesis of hexaradical imino nitroxide compounds follows the Ullman procedure involving the condensation of 2,3-bis(hydroxylamino)-2,3-dimethylbutane with hexa-(4-formylphenoxy)cyclotriphosphazene (3) followed by oxidation of the condensation product hexa-[4-(1-hydroxy-4,4,5,5-tetramethyl-2-imidazoline-2-yl)phenoxy]cyclotriphosphazene (2) by NaIO₄. Characterization of hexaradical was performed by X-ray and SQUID in solid state and by EPR, absorption spectroscopy, and electrochemistry in solution. CV of 1 shows an oxidation peak at 1.184 V (vs SCE) and a reduction peak at -0.883 V, both characteristics of the presence of phenyl imino nitroxide (7) moieties, suggesting that the contribution of the cyclotriphosphazene core is negligible. Attention was particularly focused on developing methods, UV-vis spectroscopy and square-wave voltammetry, to quantify the number of radicals in a way to confirm easily and rapidly the polyradicals' structure.

Fluorination of phthalocyanine substituents: Improved photoproperties and enhanced photodynamic efficacy after optimal micellar formulations

A fluorinated phthalocyanine and its non-fluorinated analogue were selected to evaluate the potential enhancement of fluorination on photophysical, photochemical and redox properties as well as on biological activity in cellular and animal models. Due to the pharmacological relevance, the affinity of these phthalocyanines towards biological membranes (logP_ow) as well as their primary interaction with human serum albumin (HSA) or low-density lipoprotein (LDL) were determined. Water-dispersible drug formulation of phthalocyanines via Pluronic^®-based triblock copolymer micelles was prepared to avoid self-aggregation effects and to improve their delivery. The obtained results demonstrate that phthalocyanines incorporation into tunable-polymeric micelles significantly enhanced their cellular uptake and their photocytotoxicity. The improved biodistribution and photodynamic efficacy of the phthalocyanines-triblock copolymer conjugates was also confirmed in vivo in CT26 bearing BALB/c mice. PDT with both compounds led to tumor growth inhibition in all treated animals. Fluorinated phthalocyanine 2 turned out to be the most effective anticancer agent as the tumors of 20% of mice treated regressed completely and did not appear for over one year after treatment.

Phthalocyanine-chalcone conjugates

A phthalocyanine-chalcone conjugate was previously reported to retain the full photodynamic activity of the phthalocyanine and a slightly lowered antivascular effect of the chalcone. Assuming that it was due to an insufficient release of the chalcone, we described here several grafting modes applied to the preparation of phthalocyanine-chalcone conjugates.

Mechanism of the Zn(II)Phthalocyanines' Photochemical Reactions Depending on the Number of Substituents and Geometry

In this work, the synthesis and the nonlinear absorption and population dynamics investigation of a series of zinc phthalocyanines (ZnPcs) dissolved in chloroform are reported. In order to determine the relevant spectroscopic parameters, such as absorption cross-sections of singlet and triplet excited states, fluorescence relaxation times, intersystem crossing, radiative decay and internal conversion, different optical and spectroscopic techniques were used. By single pulse and pulse train Z-scan techniques, respectively, singlet and triplet excited states‘ absorption cross-section were determined at 532 nm. Furthermore, the intersystem crossing time was obtained by using both techniques combined with the fluorescence lifetime determined by time-resolved fluorescence. The radiative and internal conversion rates were determined from the fluorescence quantum yield of the samples. Such spectroscopy parameters are fundamental for selecting photosensitizers used in photodynamic therapy, as well as for many other applications.

Covalent or supramolecular combinations of resorcinarenes and porphyrinoids

Cavitands and porphyrinoids are two major groups of molecules. If cyclodextrins are maybe the most famous type of cavitands, the properties of resorcinarenes are now well known and rise rapidly increasing attention. This mini-review aims at detailing all the combinations of resorcinarenes with porphyrinoids reported so far, evidencing the bright future of such combos. In addition, two newly synthesized porphyrins-resorcinarene hybrids are reported.

The effect of “on/off” molecular switching on the photophysical and photochemical properties of axially calixarene substituted activatable silicon(iv)phthalocyanine photosensitizers

Silicon(iv) phthalocyanines (4 and 5) bearing two calixarene groups as axial ligands were synthesized. Surprisingly, both phthalocyanines were obtained as two different isomers (4a–b and 5a–b).

The optical characterization of metal-mediated aggregation behaviour of amphiphilic Zn(ii) phthalocyanines

Addition of Ag⁺ cations induces J-aggregation in ultrathin films of both symmetrically and asymmetrically substituted Zn(ii) phthalocyanines.

Methylsulfonyl Zn phthalocyanine: A polyvalent and powerful hydrophobic photosensitizer with a wide spectrum of photodynamic applications

BACKGROUND

The biomedical photodynamic principle is based on the light-induced and photosensitizer-mediated killing of unwanted or harmful cells by overproduction of reactive oxygen species. Motivated by the success of photodynamic therapy (PDT) against several types of tumors, further applications of this approach are constantly identified which require the design and synthesis of novel photosensitizers with specifically tailored properties for a particular clinical application.

METHODS

Hydrophobic photosensitizers are currently gaining attention and hence a tetramethylsulfonyl Zn(II) phthalocyanine (2) was designed with respect to the desired photoproperties. The photodynamic potential of 2 was assessed by the determination of its photophysical and photochemical properties, and by a large range of biological tests including its phototoxicity against cancer cells and Gram(+) bacteria. Unsubstituted ZnPc was used as a reference compound for comparison purposes.

RESULTS

Phthalocyanine 2 has a better oxygen generation and is more photostable than ZnPc. 2 is a polyvalent and powerful hydrophobic photosensitizer with a wide spectrum of photodynamic applications against cancer (tested on A431 cells) and for Gram(+) PDI. Against Staphylococcus aureus, a maximum photokilling efficiency of more than 6 log10 steps was induced by a 5μM concentration of 2, outperforming the 3 log10 criterion for an antimicrobial effect (according to the recommendation of the American Society for Microbiology) by more than three orders of magnitude.

CONCLUSIONS

Phthalocyanine 2 has attractive photophysical and -chemical characteristics. Initial evaluation of its application in anti-tumor PDT and PDI suggest potential for further pre-clinical and clinical development of this compound.

Site-selective formation of an iron(iv)-oxo species at the more electron-rich iron atom of heteroleptic μ-nitrido diiron phthalocyanines

A combination of MS and computation on μ-nitrido bridged diiron complexes reveals H₂O₂ binding to the complex and generates an oxidant capable of oxidizing methane.

Iron(iv)–oxo species have been identified as the active intermediates in key enzymatic processes, and their catalytic properties are strongly affected by the equatorial and axial ligands bound to the metal, but details of these effects are still unresolved. In our aim to create better and more efficient oxidants of H-atom abstraction reactions, we have investigated a unique heteroleptic diiron phthalocyanine complex. We propose a novel intramolecular approach to determine the structural features that govern the catalytic activity of iron(iv)–oxo sites. Heteroleptic μ-nitrido diiron phthalocyanine complexes having an unsubstituted phthalocyanine (Pc1) and a phthalocyanine ligand substituted with electron-withdrawing alkylsulfonyl groups (PcSO₂R) were prepared and characterized. A reaction with terminal oxidants gives two isomeric iron(iv)–oxo and iron(iii)–hydroperoxo species with abundances dependent on the equatorial ligand. Cryospray ionization mass spectrometry (CSI-MS) characterized both hydroperoxo and diiron oxo species in the presence of H₂O₂. When m-CPBA was used as the oxidant, the formation of diiron oxo species (PcSO₂R)FeNFe(Pc1) Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O was also evidenced. Sufficient amounts of these transient species were trapped in the quadrupole region of the mass-spectrometer and underwent a CID-MS/MS fragmentation. Analyses of fragmentation patterns indicated a preferential formation of hydroperoxo and oxo moieties at more electron-rich iron sites of both heteroleptic μ-nitrido complexes. DFT calculations show that both isomers are close in energy. However, the analysis of the iron(iii)–hydroperoxo bond strength reveals major differences for the (Pc1)FeN(PcSO₂R)Fe^IIIOOH system as compared to (PcSO₂R)FeN(Pc1)Fe^IIIOOH system, and, hence binding of a terminal oxidant will be preferentially on more electron-rich sides. Subsequent kinetics studies showed that these oxidants are able to even oxidize methane to formic acid efficiently.

Modulation of the electronic and spectroscopic properties of Zn(II) phthalocyanines by their substitution pattern

Four isomerically pure octasubstituted zinc phthalocyanines with variations in the attachment atom and positions of the substituents were selected for a systematic investigation of the effect of the substitution pattern on their electronic and spectroscopic properties. Effects which were investigated are the position, the electron donating and withdrawing properties, and the donating force of the substituent. The results are discussed and interpreted based on theoretical and experimental determination of the orbital levels. This work allows us to highlight which substitution patterns are the most suitable considering different common applications of phthalocyanines.

Copper Phthalocyanine Functionalized Single-Walled Carbon Nanotubes: Thin Films for Optical Detection

Thin films of non-covalently hybridized single-walled carbon nanotubes (SWCNT) and tetra-substituted copper phthalocyanine (CuPcR4) molecules have been produced from their solutions in dimethylformamide (DMF). FTIR spectra revealed the 7π-7π interaction between SWCNTs and CuPcR4 molecules. DC conductivity of films of acid-treated SWCNT/CuPcR4 hybrid has increased by more than three orders of.magnitude in comparison with conductivity of CuPcR4 films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements have shown that films obtained from the acid-treated SWCNTs/CuPcR4 hybrids demonstrated more homogenous surface which is ascribed to the highly improved solubility of the hybrid powder in DMF Using total internal reflection ellipsometry spectroscopy (TIRE), thin films of the new hybrid have been examined as an optical sensing membrane for the detection of benzo[a]pyrene in water to demonstrate the sensing properties of the hybrid.

1,4,8,11,15,18,22,25-Alkylsulfanyl phthalocyanines: effect of macrocycle distortion on spectroscopic and packing properties

The effect of phthalocyanine macrocycle distortion on its spectroscopic and packing properties is studied, by comparing two phthalocyanines octa-non-peripherally substituted by alkanethiols of different bulkiness (n-hexyl and tert-butyl).

The synthesis of an octasubstituted monohydroxylated phthalocyanine designed to investigate the effect of the presence of active moieties

Filling a lack: monofunctionalized octasubstitution, the missing substitution pattern of phthalocyanines.

Asymmetric zinc phthalocyanines substituted with a single carboxyl and triethyleneoxysulfonyl groups: synthesis, characterization and validation for photodynamic therapy

This work describes modular pathway towards the synthesis of new specific unsymmetrically (AB3) zinc phthalocyanines that contains three polyoxy ethylene and monocarboxylic acid groups as photosensitizers. Their photophysical and photochemical properties are studied. General trends are described for quantum yields of fluorescence, photodegradation and singlet oxygen quantum yields of these compounds. Therefore, these novel phthalocyanines could potentially be good photosensitizers for photodynamic therapy.

Improved photodynamic efficacy of Zn(II) phthalocyanines via glycerol substitution

Phthalocyanines are excellent photosensitizers for photodynamic therapy as they have strong absorbance in the near infra-red region which is most relevant for in vivo activation in deeper tissular regions. However, most phthalocyanines present two major challenges, ie, a strong tendency to aggregate and low water-solubility, limiting their effective usage clinically. In the present study, we evaluated the potential enhancement capability of glycerol substitution on the photodynamic properties of zinc (II) phthalocyanines (ZnPc). Three glycerol substituted ZnPc, 1–3, (tetra peripherally, tetra non-peripherally and mono iodinated tri non-peripherally respectively) were evaluated in terms of their spectroscopic properties, rate of singlet oxygen generation, partition coefficient (log P), intracellular uptake, photo-induced cytotoxicity and vascular occlusion efficiency. Tetrasulfonated ZnPc (ZnPcS₄) was included as a reference compound. Here, we showed that 1–3 exhibited 10–100 nm red-shifted absorption peaks with higher molar absorptivity, and at least two-fold greater singlet oxygen generation rates compared to ZnPcS₄. Meanwhile, phthalocyanines 1 and 2 showed more hydrophilic log P values than 3 consistent with the number of glycerol attachments but 3 was most readily taken up by cells compared to the rest. Both phthalocyanines 2 and 3 exhibited potent phototoxicity against MCF-7, HCT-116 and HSC-2 cancer cell-lines with IC₅₀ ranging 2.8–3.2 µM and 0.04–0.06 µM respectively, while 1 and ZnPcS₄ (up to 100 µM) failed to yield determinable IC₅₀ values. In terms of vascular occlusion efficiency, phthalocyanine 3 showed better effects than 2 by causing total occlusion of vessels with diameter <70 µm of the chorioallantoic membrane. Meanwhile, no detectable vascular occlusion was observed for ZnPcS₄ with treatment under similar experimental conditions. These findings provide evidence that glycerol substitution, in particular in structures 2 and 3, is able to improve the photodynamic properties of ZnPc.

Liquid crystalline alkylthia-substituted novel phthalocyanines: synthesis and characterization

Methylene-bridged tetra- and octa-alkylthia substituted metal free- and Ni ( II ) phthalocyanines were synthesized from the corresponding phthalonitrile derivatives in the presence of the anhydrous metal salt ( NiCl 2) or a strong organic base. The new compounds were fully characterized by elemental analyses, UV-vis, IR, NMR and mass spectra. The mesogenic properties of these materials were studied by differential scanning calorimetry, optical microscopy and X-ray diffraction investigations. X-ray diffraction patterns of the mesophase confirmed that the tetra- and the octa-substituted compounds formed hexagonal columnar mesophases (Colh). The mesogenic properties of these compounds were compared to that of their octa alkythia substituted phthalocyanine derivatives in the literature.