Interaction Of Phthalocyanine Research Articles

Dry ball-milling preparation and characterization of graphite–phthalocyanine composites

The hybrids of phthalocyanines with carbon nanotubes, graphene and graphene oxide were demonstrated previously to be promising for different catalytical, electrocatalytical and other applications. Nevertheless, the above carbon nanomaterials are toxic and relatively expensive. We attempted to substitute them by low-cost and harmless graphite, using dry ball-milling of graphite–phthalocyanine mixtures under mild conditions. According to scanning electron microscopy imaging and powder X-ray diffraction, the composites obtained exhibit the absence of crystalline phthalocyanine phase, which implies high efficiency of phthalocyanine milling. According to Raman spectroscopy data, the mechanochemical treatment does not provoke the formation of large amounts of defects in graphite, but instead helps its exfoliation. The composites were characterized by UV-visible spectroscopy and thermal gravimetric analysis, which showed that all of them exhibit a reduced thermal stability compared to unprocessed graphite by roughly 100–250 °C. The strength of interaction of phthalocyanines with a graphene sheet (as a graphite surface model), geometries and selected electronic parameters (frontier orbital and spin density distribution, HOMO-LUMO gap energies) of the resulting noncovalent complexes were analyzed at the PBE-D2/DNP theoretical level. The interactions of phthalocyanines with the graphene sheet are strong, with the calculated formation energies (absolute values) for the noncovalent complexes of 62.1–70.1 kcal/mol.

Interaction of free-base and 3d metal(II) phthalocyanines with open-shell endohedral fullerenes species N@C60 and P@C60

We studied theoretically the interactions of phthalocyanines (Pcs) of general formula MPc (M = 2H, Mn, Fe, Co, Ni, Cu, Zn) with endohedral fullerenes (EFs) N@C60 and P@C60, at the PBE-D/DNP theoretical level. All MPcs can form stable noncovalent complexes with both N@C60 and P@C60. The binding energies vary between −17.7 and −31.1 kcal/mol. Complexation pattern depends on the central atom of MPc, but not on the endohedral species (N or P): for H2Pc, two central H atoms approach the carbon atoms of C60 of adjacent 5:6:6 junctions; for MnPc, manganese atom coordinates to two carbon atoms of 6,6 C-C bond; for other MPcs, the central metal coordinates to 5:6:6 junction of fullerene. In MPc+N@C60 HOMO is localized exclusively on phthalocyanine, with LUMO found mostly on fullerene. In MPc+P@C60 complexes, HOMO has essentially the same localization and shape, but LUMO distribution is variable. After complexation with MPcs, no tangible changes are observed in the N and P spin state. MnPc, CoPc and CuPc having open-shell metal atoms behave differently: while the complexation has almost no effect on Cu spin, and causes only a moderate decrease in Co spin, Mn atom transfers roughly two-thirds of its unpaired electrons to fullerene.

The recent studies about the interaction of phthalocyanines with DNA

Cancer is one of the major diseases affecting all humanity with high mortality rates worldwide. Its treatment is difficult, long-term and expensive. Due to its side effects, it is troublesome for both the patient and their attendants. Cancer treatment is basically divided into three: surgery, chemotherapy and radiotherapy. Photodynamic therapy offers one of the most important and promising treatment methods, especially in recent years. Photodynamic therapy takes the steps of administering the photo-sensitizing compound to the body and stimulating it with a light of appropriate wavelength after its accumulation in the target tissue. With the formation of complex processes that take place in the target area with the reactive oxygen species formed by the stimulated compounds, death or the inhibition of the proliferation of the cells causes situations such as the destruction of the target tissue. Phthalocyanines constitute an important group of photo-sensitizers used in photodynamic therapy. Stability of these compounds and their strong absorption close to therapeutic window make these compounds important. With large Π systems, they can bind with many biological macromolecules, including DNA, with high affinity by many mechanisms, including the Π - Π stacking. This review article describes the last three years of studies in the WOS database about the interactions of phthalocyanines with DNA. The interactions of phthalocyanines with DNA are important as they can make a difference in the proliferation of tumor cells. On the other hand, DNA replication and transcription has increased due to the increasing metabolic rate of these cells. The DNA double strand opened during replication, and gene expression allows the formation of different secondary structures such as hairpin, triple, junctions, and G-quadruplex. The interaction of G-quadruplex DNA structures with these compounds, which can be formed in the guanine-rich regions of the DNA sequences opened in these processes, has been described in studies.

Design of photodynamic chitosan hydrogels bearing phthalocyanine-colistin conjugate as an antibacterial agent.

The fabrication of a new antibacterial system is an essential medical requirement to treat wounds caused by multidrug-resistant Gram-negative bacteria, mostly Pseudomonas aeruginosa. Antibacterial photodynamic therapy (APDT) is an encouraging therapy modality for bacterial infection. Anyhow, the applications of most photosensitizers are restricted by their poor water solubility and their inefficiency in disruption of the outer membrane of Gram-negative bacteria. In this context, zinc phthalocyanine-colistin (ZnPc-Col) conjugate as a new photosensitizer was synthesized in the hope of improving interaction of phthalocyanine with the surface of Gram-negative bacteria. Overcoming the low solubility of phthalocyanine, was achieved by the incorporation of ZnPc-Col into chitosan hydrogel. The weight percentages of ZnPc-Col and glutaraldehyde had remarkable effects in determining the hydrogel microstructure. Different spectroscopic methods, SEM, and rheological measurements were used to assess the properties of ZnPc-Col and prepared hydrogels. The photosensitizing activity of the hydrogels was investigated by application of 1,3-diphenylisobenzofuran as a singlet oxygen chemical quencher. Hydrogels bearing zinc phthalocyanine-colistin adduct revealed an improved APDT efficiency compared to hydrogels containing just zinc phthalocyanine component. This enhancement has been seen against P. aeruginosa.

Synthesis of non-peripheral thioanisole-substituted phthalocyanines: Photophysical, electrochemical, photovoltaic, and sensing properties

Abstract This work reports on the synthesis, characterization, photophysical, electrochemical, photovoltaic and sensing properties of non-peripherally tetra 4-(methylthio)phenoxy substituted metal-free (2), Zn(II) (3) and Co(II) (4) phthalocyanine derivatives. Confirmation of the synthesized phthalocyanine structures which have the good solubility in organic solvents, performed with a combination of elemental analysis, FTIR, 1H NMR, 13C NMR, UV–vis and MALDI-MS spectral data. Electrochemical measurements exhibit that the complex (4) shows the redox reactions taking place on both metal center and the ring while the phthalocyanines (2) and (3) give only ring-based redox reactions. All the complexes were examined for utilization in dye-sensitized solar cells (DSSCs) in the presence of chenodeoxycholic acid and the highest power conversion efficiency was achieved for the complex (3), as 1.09%. The interaction of phthalocyanines (2) and (3) with Ag+ and Pd2+ ions and their aggregation properties (H- or J- Aggregation) were investigated by UV–vis spectroscopy. Photophysical (fluorescence quantum yield) properties of the complexes (2) and (3) were reported in different solvents, such as tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO). The results of spectral measurements in these solvents showed that ΦF value of the complexes (2) and (3) were found to be lower than the unsubstituted ZnPc.

Synergistic Interaction of Phthalocyanines and Semiconductor Quantum Dots for Advanced Co-Sensitized Solar Cells

Quantum dots (QDs) are among potential key players in the next generation of photovoltaic devices [1] due to their low-cost solution-phase processability, large absorption cross sections, a spectrally tunable absorption onset (achieved via the quantum size effect), and enhanced multiple exciton generation or carrier multiplication.[2] After the first report on a certified QD solar cell, a remarkable progress has been reached just in a couple of years obtaining certified power conversion efficiencies (PCEs) approaching 9%.[3] On the other hand, phthalocyanines (Pcs) are outstanding dye candidates in dye sensitized solar cells (DSSCs) due to their high extinction coefficient in the infrared spectral region and to their high thermal and chemical stabilities.[4] Pcs incorporated in DSSCs have achieved PCEs as high as 6.4 %,[5] still far away of the 12.75% PCE obtained by porphyrins, their closest relatives. An elegant strategy to improve the light-harvesting ability of the Pcs is the binding, either covalent or supramolecular, to a complementary chromophore, such as QDs, able to undergo efficient electron transfer to the charge injecting system. However, the chemical combination of Pc rings to QDs has hardly been explored probably due to the difficulties to synthesize Pcs with the adequate anchoring groups. Herein, we will report our more recent results related with the synthesis of different unsymmetrically substituted phthalocyanines containing sulphur atom (see Figure 1 as example) and the improvement in efficiency of QD solar cells through their co-sensitization with phthalocyanines.[6] Acknowledgements. This work has been supported by the Spanish Ministerio de Economía y Competitividad, Generalitat Valenciana and the European FEDER funds (grants CTQ2011-26455, PROMETEO 2012/010 and ISIC/2012/008) Figure 1. Chemical structure of a disulfide substituted bisphthalocyanine Figure 1

Spectroscopic investigation on the interaction of copper porphyrazines and phthalocyanine with human telomeric G-quadruplex DNA

The G-quadruplex DNA is a novel target for anticancer drug discovery and many scientific groups are investigating interaction of small molecules with G-quadruplex DNA to discover therapeutic agents for cancer. Here, interaction of a phthalocyanine (Cu(PcTs)) and two tetrapyridinoporphyrazines ([Cu(2,3-tmtppa)]4+ and [Cu(3,4-tmtppa)]4+) with Na+ and K+ forms of human telomeric G-quadruplex DNA has been investigated by spectroscopic techniques. The results indicated that interaction of the cationic porphyrazines is remarkably stronger than the anionic phthalocyanine and they presumably bind to the G-quadruplex DNA through end-stacking. Fluorescent intercalator displacement assay implied the displacement ability of the complexes with thiazole orange. In addition, circular dichroism spectra of both quadruplex forms converge to the Na+ isoform after binding to the porphyrazines. In conclusion, the porphyrazines as the complexes that bind to the G-quadruplex DNA, could be suitable candidates for further investigations about inhibition of telomerase enzyme.

Theoretical Insights into Adsorption of Cobalt Phthalocyanine on Ag(111): A Combination of Chemical and van der Waals Bonding

In this article we study in detail the interaction of cobalt phthalocyanine (CoPc) with the Ag(111) surface by means of density functional theory calculations (DFT). We discuss the electronic and geometric differences of the adsorbed CoPc as it interacts with the different binding sites of the surface, yielding deeper insight into the adsorption mechanism of organometallic molecules with noble metal surfaces. We interpret the experimentally observed 4-fold to 2-fold symmetry reduction upon interaction of phthalocyanine molecules with metal surfaces as caused by electronic effects originating from nonsymmetric interactions between the molecule and the surface. To asses the role of dispersion forces in bonding of CoPc to the surface we employ a semiempirical dispersion correction to standard DFT and compare the obtained molecule–surface separation with experimental measurements. We show that, in the case of CoPc, the molecule bonds to the surface mostly due to covalent bonding between Co and Ag, but with a ...

Modeling the interactions of phthalocyanines in water: From the Cu(II)-tetrasulphonate to the metal-free phthalocyanine

A quantum and statistical study on the effects of the ions Cu(2+) and SO(3)(-) in the solvent structure around the metal-free phthalocyanine (H(2)Pc) is presented. We developed an ab initio interaction potential for the system CuPc-H(2)O based on quantum chemical calculations and studied its transferability to the H(2)Pc-H(2)O and [CuPc(SO(3))(4)](4-)-H(2)O interactions. The use of the molecular dynamics technique allows the determination of energetic and structural properties of CuPc, H(2)Pc, and [CuPc(SO(3))(4)](4-) in water and the understanding of the keys for the different behaviors of the three phthalocyanine (Pc) derivatives in water. The inclusion of the Cu(2+) cation in the Pc structure reinforces the appearance of two axial water molecules and second-shell water molecules in the solvent structure, whereas the presence of SO(3)(-) anions implies a well defined hydration shell of about eight water molecules around them making the macrocycle soluble in water. Debye-Waller factors for axial water molecules have been obtained in order to examine the potential sensitivity of the extended x-ray absorption fine structure technique to detect the axial water molecules.

The interactions of phthalocyanines with stimulated and resting human peripheral blood mononuclear cells.

The interactions of two metal-free phthalocyanines [(H2Pc) and Solar Pc (with four peripherical groups: SO2N(CH2CH2OH)2)] and of one metal substituted dye (CoPc) with resting and stimulated human peripheral blood mononuclear cells (PBMC) were compared. The absorption, fluorescence, photoacoustic and EPR spectra of both resting cells and cells stimulated by phytohaemagglutinin, incubated in dimethyl sulfoxide (DMSO) with very low or 95% water content and with or without dye addition, were measured. The fate of the light absorbed by the samples was investigated. It is known that singlet oxygen production is crucial for photodynamic action of dyes. Thermal deactivation and luminescence emission compete with this process, so investigation of these alternative paths of sensitizer deactivation provides information about photodynamic action. The incorporation of the investigated dyes into cells and the perturbation of the cell structure caused by the dyes, the incubation solvent and the activator were investigated by comparing the spectral properties of PBMC before and after stimulation and incubation. Incubation of the cells for 1 h in a solution of Solar Pc in 99.5% aqueous DMSO, resulted in an efficient dye incorporation which was highly selective. Solar Pc being introduced much more efficiently into stimulated cells than into resting cells.

Molecular Interaction of Phthalocyanine Studied by Electroabsorption in Near IR

The linear and the nonlinear optical properties of soluble phthalocyanines in the condensed states were investigated by the absorption and the electroabsorption spectra. By a Kramers-Krönig analysis of the electroabsorption spectra, the wavelength of the maximum refractive index changes is located at around 980 nm for the casted polymer film doped with binuclear phthalocyanine.

Interaction of phthalocyanines with lipid membranes: a spectroscopic and functional study on isolated rat liver mitochondria

Absorption and emission spectroscopic studies on Zn(II)-phthalocyanine (ZnPc) incorporated into unilamellar liposomes of dipalmitoylphosphatidylcholine, sometimes added with cholesterol or cardiolipin, and released to rat liver mitochondria via the three types of liposomal vesicles indicated that: (a) ZnPc predominantly dissolves in all lipid domains of biological membranes with the exception of cardiolipin-containing regions; a partial localization of ZnPc in protein binding sites is also postulated; (b) the spectroscopic properties of ZnPc, although mainly determined by the aggregation state of the dye, are somewhat influenced by the physico-chemical characteristics of the lipid environment; (c) ZnPc-binding lipid domains in mitochondria are mainly localized in the outer membrane; this conclusion is clearly deduced from the trends of Arrhenius plots of the ZnPc fluorescence quantum yield in whole mitochondria and isolated inner or outer membrane in the temperature range − 10°C- + 45°C; (d) the nature of the ZnPc-binding site in mitochondria is not dependent on the chemical composition of the liposome carrier, contrary to what observed for other hydrophobic dyes, such as porphyrins. This has been also confirmed by photosensitization experiments. Actually, illumination of ZnPc-loaded mitochondria by 600–700 nm light causes a decline of the respiratory control ratio, which is essentially dependent on the amount of incorporated photosensitizer, irrespective of the composition of the carrier.

The interaction of phthalocyanine with planar lipid bilayers: Photodynamic inactivation of gramicidin channels

The effect of phthalocyanines, the potent photodynamic sensitizers, on the electric properties of the bilayer lipid membrane (BLM) is studied. It is shown, that tetrasulfonated, as well as trisulfonated, aluminium phthalocyanine do not alter the conductance of BLM, but elicit certain changes in the boundary potential difference, which points in favor of dye adsorption on BLM. Under the conditions of intense visible light irradiation, the phthalocyanines cause an increase in the conductance, resulting in the irreversible breakdown of BLM, formed from soy bean phosphati-dylcholine, but fail to change the conductance of BLM, formed from diphytanoilphosphatidylcholine. The phthalocyanine-sensitized inactivation of gramicidin channels incorporated into BLM is observed under the conditions of weak visible light irradiation using an He-Ne laser. The photodynamic blockage of model ionic channels is considerably suppressed after oxygen depletion. The phenomenon consists of a marked reduction of a number of open channels, probably due to photomodification of tryptophan residues, essential for gramicidin functioning. The mechanism of the channel inactivation, involving the photosensitized reaction of the II type, and the relevance to the interaction of sensitizers with biomembranes, is discussed.