Amphiphilic Cationic Phthalocyanines for Photodynamic Therapy of Cancer

Effective interaction with biomembranes is essential for activity of photosensitizers; however, majority of them are highly charged symmetrical species. Amphiphilic cationic phthalocyanines differing in bulkiness of substitution on lipophilic part (-H, -SMe, -StBu) were therefore prepared. Compounds had high singlet oxygen production (ΦΔ =0.38-0.46, DMSO), good fluorescence emission (ΦF =0.21-0.26, DMSO), and log P values ranging -0.07-1.1 (1-octanol/PBS). Study of interaction with liposomes revealed that also bulky -StBu derivatives are able to enter biomembranes. Detail in vitro studies (toxicity, subcellular localization, type of cell death, and morphology) were performed. Compounds were characterized by excellent EC50 values in range of dozens of nM (HeLa, EA.hy926, MCF-7, HCT116), which were dependent on drug-light interval and reached plateau after 4 h on HeLa cells. Well-balanced lipophilicity with ability to interact with biomembranes rank these derivatives among perspective photosensitizers, even for vascular-targeted PDT (VTP) since they kill EA.hy926 without any preincubation time.

[3 + 1] Mixed Cyclization: A Synthetic Route to Prepare Low-Symmetry Phthalocyanines

A novel synthetic strategy for low-symmetry phthalocyanines has been developed, which involves the base-promoted cyclization of a preconnected trisphthalonitrile and a free phthalonitrile in the presence of a metal template. By using this [3 + 1] mixed cyclization approach, a series of zinc(II) phthalocyanine derivatives have been synthesized in up to 12% yields, including a very rare ABCD-type phthalocyanine and an amphiphilic ABAC-type analogue that can self-assemble in aqueous media, forming stable spherical nanoparticles.

A3B type unsymmetrical and amphiphilic phthalocyanines: Synthesis, characterization, thermal stability and aggregation studies

This study reports the preparation, analysis, aggregation statuses and thermal properties of five phthalocyanines. The preparation of all molecules includes two steps: the first step is the preparation of phthalocyanine precursor molecules (A and B coded phthalonitriles); the second step is the synthesis of one metal-free and four metalled phthalocyanines (A₃B-Co, A₃B-Cu, A₃B-H, A₃B-Ni, and A₃B-Zn coded compounds). Compound A holds a hydrophobic chain (cetyl alcohol); compound B holds a hydrophilic chain (tetraethylene glycol). Phthalocyanines include three hydrophobic chains and one hydrophilic chain (A₃B type phthalocyanine). Characterization methods which were used to determine the structure of these compounds are Fourier Transform Infrared (FTIR), Proton Nuclear Magnetic Resonance (¹H NMR), Carbon-13 Nuclear Magnetic Resonance (¹³C NMR), and Ultraviolet Visible (UV Vis) spectroscopies and elemental analysis. The phthalocyanines have high stability up to 260 °C as a minimum value. Aggregation statuses of the phthalocyanines change to the metal from the metal or to the solvent from the solvent.

Super-Sensitive Protonation Behavior of Trifluoroethoxy-Substituted Phthalocyanines and Their Application to Solvent Discrimination

The super-sensitive protonation behavior of trifluoroethoxy-substituted phthalocyanines (TFEO-Pcs) was carefully studied using UV-vis and fluorescence spectroscopy, as well as computational calculations. The practical utility of TFEO-Pcs in sensor technology was demonstrated by identifying chloroform samples from different commercial sources.

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.

Efficient synthesis of EDOT modified ABBB-type unsymmetrical zinc phthalocyanine: optoelectrochromic and glucose sensing properties of its copolymerized film

A new EDOT-based monomer bearing zinc phthalocyanine was synthesized and the electrochromic and biosensing properties of electropolymers derived from it were investigated.

ABAB Phthalocyanines: Scaffolds for Building Unprecedented Donor-π-Acceptor Chromophores

Unique donor–π–acceptor phthalocyanines have been synthesized through the asymmetric functionalization of an ABAB phthalocyanine, crosswise functionalized with two iodine atoms through Pd‐catalyzed cross‐coupling reactions with adequate electron‐donor and electron‐acceptor moieties. These push–pull molecules have been optically and electrochemically characterized, and their ability to perform as chromophores for dye‐sensitized solar cells has been tested.

Monoisomeric phthalocyanine-fullerene dyads with e- and cis-3 addition pattern; synthesis, modeling, photovoltage and solar cell experiments

Synthesis and characterization of two A 2 B 2-type monoisomeric phthalocyanines and phthalocyanine-fullerene (Pc- C 60) dyads, in which fullerene is regioselectively attached to phthalocyanine with two linkers, are described. 1 H NMR spectroscopy results clearly indicate an e addition pattern of the fullerene moiety in trans-dyad 9, and apparently a cis-3 addition pattern in cis-dyad 10. The possible spatial arrangements of 9 and 10 were further examined by molecular modeling. The dyads have polar (– OH ) side chains on the fullerene side of the dyad providing a possibility to produce oriented donor–acceptor (D–A) Langmuir monolayers on aqueous subphase, which can be shifted onto a solid surface. When deposited on a solid electrode material, parallel vertical alignment of the phthalocyanine and fullerene moieties in 100% dyad monolayer was obtained and vertical electron transfer from Pc to C 60 upon photoexcitation was demonstrated. Introduction of the dyads as an oriented interfacial monolayer between the photoactive layer and metal anode improved the power conversion efficiency in inverted organic solar cells.

Heteroatom-substituted tetra(3,4-pyrido)porphyrazines: a stride toward near-infrared-absorbing macrocycles

Synthesis and photophysical properties are reported for substituted tetra(3,4-pyrido)porphyrazines that absorb light as far as at 800 nm.

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.

Regioisomer-Free C 4h β-Tetrakis(tert-butyl)metallo-phthalocyanines: Regioselective Synthesis and Spectral Investigations

Metal β-tetrakis(tert-butyl)phthalocyanines are the most commonly used phthalocyanines due to their high solubility, stability, and accessibility. They are commonly used as a mixture of four regioisomers, which arise due to the tert-butyl substituent on the β-position, and to the best of our knowledge, their regioselective synthesis has yet to be reported. Herein, the C_4h-selective synthesis of β-tetrakis(tert-butyl)metallophthalocyanines is disclosed. Using tetramerization of α-trialkylsilyl phthalonitriles with metal salts following acid-mediated desilylation, the desired metallophthalocyanines were obtained in good yields. Upon investigation of regioisomer-free zinc β-tetrakis(tert-butyl)phthalocyanine using spectroscopy, the C_4h single isomer described here was found to be distinct in the solid state to zinc β-tetrakis(tert-butyl)phthalocyanine obtained by a conventional method.

Effect of intramolecular charge transfer on fluorescence and singlet oxygen production of phthalocyanine analogues

Intramolecular charge transfer (ICT) was studied on a series of magnesium, metal-free and zinc complexes of unsymmetrical tetrapyrazinoporphyrazines and tribenzopyrazinoporphyrazines bearing two dialkylamino substituents (donors) and six alkylsulfanyl or aryloxy substituents (non-donors). The dialkylamino substituents were responsible for ICT that deactivated excited states and led to considerable decrease of fluorescence and singlet oxygen quantum yields. Photophysical and photochemical properties were compared to corresponding macrocycles that do not bear any donor centers. The data showed high feasibility of ICT in the tetrapyrazinoporphyrazine macrocycle and significantly lower efficiency of this deactivation process in the tribenzopyrazinoporphyrazine type molecules. Considerable effect of non-donor peripheral substituents on ICT was also described. The results imply that tetrapyrazinoporphyrazines may be more suitable for development of new molecules investigated in applications based on ICT.

Mono-, bis- and tetrahydroxy phthalocyanines as building blocks for monomolecular layer assemblies

We have developed three basic phthalocyanine structures, containing one, two, or four hydroxy groups, which are simple to synthesize and purify, as well as can be characterized well by NMR and MS. These building blocks can easily be further modified to have anchor groups, which make the molecules suitable for attachment to solid substrates. We have used thioacetate and pentafluorophenyl ester moieties, giving target phthalocyanines the ability to self-assemble on gold, metal oxides, and glass. Bonding densities calculated from the absorbances of the layers suggest mean molecular area to be in the range of 1–3 nm2, which can be partially controlled by side substituents and the number of linkers.

Photophysical and theoretical insights on non-covalently linked fullerene-zinc phthalocyanine complexes

The photo-physical aspects of non-covalently linked assemblies of a series of fullerenes, namely, C60, C70, tert-butyl-(1,2-methanofullerene)-61-carboxylate (1) and [6,6]-phenyl C70 butyric acid methyl ester (2) with a designed zinc phthalocyanine (ZnPc), viz., zinc-1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (3) in toluene medium are studied employing absorption spectrophotometric, steady state and time resolved fluorescence spectroscopic measurements. Of central interest in these investigations is the preferential binding of various fullerenes with ZnPc in toluene. The ground state interaction between fullerenes and 3 is first evidenced from UV-Vis measurements. Steady state fluorescence experiment reveals efficient quenching of the excited singlet state of 3 in presence of both underivatized and derivatized fullerenes. K values for the complexes of C60, C70, 1 and 2 with 3 are determined to be 6500, 22,230, 47,800 and 54,770 dm3 mol(-1), respectively. The magnitude of K suggests that 3 preferentially binds C70 and derivatized C70 in comparison to C60 and 1. Time resolved emission measurements establish that C(70)-3 and 2-3 complexes are stabilized much more in comparison to C(60)-3 and 1-3 systems in terms of charge separation process. Semi empirical calculations employing third parametric method substantiate the strong binding of C70 and its derivative with 3 in terms of heat of formation values of the respective complexes, and at the same time, determine the orientation of bound guest (here fullerenes) with the molecular plane of 3.

Peripheral substitution of a near-IR-absorbing soluble phthalocyanine using "click" chemistry

A series of near-IR-absorbing soluble phthalocyanines (Pcs) with eight alkyne moieties as side chains of the chromophore have been synthesized. One of these Pcs has been used as a scaffold for functional group modification using alkyne-azide click chemistry with various azides. This led to a small library of Pcs with photo and thermal crosslinkable, dendritic, and hydrophilic moieties starting from a single Pc molecule. A patterned thin film was fabricated by photocrosslinking one of these Pc derivatives.

Solid-phase synthesis of azaphthalocyanine-oligonucleotide conjugates and their evaluation as new dark quenchers of fluorescence

Hydrophobic nonaggregating metal-free azaphthalocyanines (AzaPc) of the tetrapyrazinoporphyrazine type were synthesized, characterized, and used for oligonucleotide labeling. Both 3'-end and 5'-end labeling methods using solid phase synthesis suitable for automatic processes in the DNA/RNA synthesizer were developed. The hydrophobic character of AzaPc enabled the anchoring of the conjugates on reverse phase of the oligonucleotide purification cartridge, thus enabling their simple purification. AzaPc did not show any fluorescence and extremely low singlet oxygen quantum yields (Φ(Δ) = 0.015-0.018 in DMF) in a monomeric state due to ultrafast intramolecular charge transfer. That is why they were investigated as a new dark quencher structural type. They profit particularly from absorption in a wide range of wavelengths (300-740 nm) that covers all fluorophores used in hybridization assays nowadays. As an example, quenching efficiency was evaluated in a simple hybridization assay using monolabeled probes. AzaPc-based probes efficiently quenched both fluorescein and Cy5 fluorescence by both resonance energy transfer and contact quenching. The results were compared with three established dark quenchers, and the AzaPc exerted better (BHQ-1 and BHQ-2) or comparable (BBQ-650) quenching efficiencies for both fluorophores.