Silicon Phthalocyanine Dichloride Research Articles

Comparing Singlet Oxygen Generation of Schiff Base Substituted Novel Silicon Phthalocyanines by Sonophotochemical and Photochemical Applications.

Although the sonophotodynamic method has an effective therapeutic outcome for anticancer treatment compared with the photodynamic method, there are not enough related studies in the literature and this study aims to contribute to the development of sonophotodynamic studies. For this purpose, the Schiff base substituted silicon phthalocyanines were designed and synthesized as effective sensitizer candidates and the photophysicochemical and sonophotochemical features of the phthalocyanines were examined to increase singlet oxygen efficiency. The calculated ΦΔ values indicate that the contribution of substituent groups improved the production of singlet oxygen compared with silicon (IV) phthalocyanine dichloride (SiPcCI2 ) and also the sonophotochemical applications increased the singlet oxygen yields. The ΦΔ values (ΦΔ =0.76 for axially bis-{4-[(E)-(pyridin-3-ylimino)methyl]phenol} substituted silicon (IV) phthalocyanine (2a), 0.68 for axially bis-4-[(E)-{[(pyridin-3-yl)methyl]imino}methyl]phenol substituted silicon (IV) phthalocyanine (2b) in photochemical study) reached to ΦΔ =0.98 for 2a, 0.94 for 2b in sonophotochemical study. This article will enrich the literature on increasing singlet oxygen yield.

Synthesis of axially Schiff base new substituted silicon phthalocyanines and investigation of photochemical and sono-photochemical properties

Sono-photodynamic therapy, which show a very high therapeutic effect compared to photodynamic therapy, is a newer method for anticancer treatments. However, unlike Photodynamic therapy (PDT), the number of studies measuring the efficiency of singlet oxygen for the Sono-photodynamic therapy (SPDT) method is quite insufficient in the literature. Therefore, this study aimed to synthesis novel axially substituted silicon (IV) phthalocyanines containing imine groups with improved photochemical properties and then reported the efficiency of singlet oxygen by both of photochemical and sono-photochemical studies. According to the results, the substituent group increased the singlet oxygen yield of silicon (IV) phthalocyanine dichloride and the sono-photochemical effect increased the singlet oxygen yields (ΦΔ=0.35 for 2a, 0.69 for 2b in photochemical study, 0.78 for 2a, 0.97 for 2b in sono-photochemical study).This article may pave the way to achieve high singlet oxygen efficiency.

Novel silicon phthalocyanines with improved singlet oxygen generation by Sono-photochemical applications

Although it has been proven, that the SPDT method, which improves the low penetration disadvantage of PDT, significantly increases the singlet oxygen yield, the number of relevant studies in the literature is limited. Therefore, this study aimed to show the improved singlet oxygen generation using newly synthesized silicon (IV) phthalocyanines containing terminal fluoro, chloro, bromo-phenoxy moiety by sono-photochemical applications. While the calculated ΦΔ values were 0.41 for compound 1, 0.39 for compound 2, and 0.29 for compound 3 after photochemical applications, these values increased to 0.77 for compound 1, 0.74 for compound 2, and 0.65 for compound 3 after sono-photochemical applications. The results proved that the contribution of the substituents increased the therapeutic efficacy of silicon (IV) phthalocyanine dichloride (SiPcCl2), and the applied irradiation method also increased the singlet oxygen yield approximately-two times. This article will enrich the literature on increasing singlet oxygen yield.

Improved singlet oxygen generation of axially ruthenium(II) complex substituted silicon(IV) phthalocyanine by sono-photochemical studies

Sono-photodynamic study, which shows an exceedingly high therapeutic outcome compared to photodynamic study, is a new alternative method for the anticancer treatments. However there are not enough related studies in the literature. Therefore, this study initially aimed to design and synthesize ruthenium (II) complex substituted silicon phthalocyanine for a suitable sono-photosensitizer and then to increase singlet oxygen production using sono-photochemical studies. The results showed that the substituent group improved the generation of singlet oxygen quantum yield of silicon (IV) phthalocyanine dichloride, and also the sono-photochemical method increased the yield approximately two times (ΦΔ=0.38 in photochemical study, 0.66 in sono-photochemical study). This article will pave the way for studies that seek to improve sono-photochemical properties.

Oxygen Reduction Reaction Catalyzed By Silicon and Nitrogen Co-Doped Carbon

Finding an alternative catalysts for the oxygen reduction reaction (ORR) has been a key issue in modernelectrocatalysis. Traditional platinum-based catalysts are not viable in the long term and thus much efforthas been focused on non-precious metal catalysts. Heteroatom doped and metal-heteroatom co-dopedcarbon materials have emerged as the main candidate for replacing the platinum-based catalysts.Different MN4 macrocycles, such as metal phthalocyanines and porphyrins, have been studied aspromising materials to prepare electrocatalysts for ORR in alkaline media [1]. While the development ofnon-precious metal and non-metal carbon catalysts has gained a lot of attention recently, non-metalphthalocyanines are a less studied topic [2].In this work a novel catalyst material including multi-walled carbon nanotubes (MWCNT) and siliconphthalocyanine dichloride (SiPcCl2) was synthesized and the electrochemical activity towards the oxygenreduction reaction (ORR) in alkaline media was studied. Different ratios of phthalocyanine-to-nanotubeswere pyrolyzed at 800 °C. After optimizing the ratio of phthalocyanine-to-nanotubes, the pyrolysis processwas also carried out at different temperatures, but the results showed that the best temperature forpyrolysis is still 800 °C. ORR activity on SiPc/MWCNT catalyst was studied in 0.1 M KOH by employingrotating disc electrode method. Physical characterization was carried out with X-ray photoelectronspectroscopy and transmission electron microscopy. The results showed successful incorporation ofsilicon and nitrogen into the carbon framework. We show that doping MWCNTs with a non-metalphthalocyanine creates a highly active ORR catalyst rivaling the activity of metal-based catalysts inalkaline conditions. This work clearly demonstrates that non-metal macrocyclic compound modifiedcarbons, similar to the the SiPc/MWCNT can be used as alternative cathode catalysts for the metal-airbatteries and alkaline membrane fuel cells.[1] Y. Liu, X. Yue, K. Li, J. Qiao, D.P. Wilkinson, J. Zhang, PEM fuel cell electrocatalysts based ontransition metal macrocyclic compounds, Coord Chem Rev. 315 (2016) 153-177.[2] K.-K. Türk, K. Kaare, I. Kruusenberg, M. Merisalu, U. Joost, L. Matisen, V. Sammelselg, J.H. Zagal, K.Tammeveski, Oxygen electroreduction on zinc and dilithium phthalocyanine modified multiwalled carbonnanotubes in alkaline media, J. Electrochem. Soc. 164 (2017) H338-H344.

Thermal Analysis, Dielectric Response and Electrical Conductivity of Silicon Phthalocyanine Dichloride (SiPcCl2) Thin Films

This research is a detailed examination of the effect of post-annealing on the structure and electrical conductivity of silicon phthalocyanine dichloride (SiPcCl2) thin films. Differential thermal analysis (DTA) is used to determine the temperature limit of thermal stability for a sample of silicon phthalocyanine dichloride (SiPcCl2). The results of differential thermal analysis (DTA) proved that silicon phthalocyanine dichloride (SiPcCl2) is thermally stable up to 415 K. The dielectric behavior and the electrical conductivity of silicon phthalocyanine dichloride (SiPcCl2) thin films were investigated under a temperature effect from 303 K to 383 K and a frequency from 200 Hz to 20 MHz. The frequency and temperature dependence of dielectric loss and dielectric constant values were explained in terms of dielectric polarization theory. The alternative current (AC) conductivity response toward the frequency change obeys Jonscher’s power law. The correlated barrier hopping (CBH) model is utilized and adapted to fit the conduction mechanism in the high- and low-frequency regions. Both the complex electric modulus and the impedance formalisms are used to illustrate the dielectric characteristics of the silicon phthalocyanine dichloride (SiPcCl2). The potential height value of the hopping barrier, Wm, and activation energy value, Eac, for dielectric relaxation were determined.

Silicon Phthalocyanine Modified Multi-Walled Carbon Nanotubes As a Novel Metal-Free Catalyst for the Oxygen Electroreduction

Finding an alternative catalysts for the oxygen reduction reaction (ORR) has been a key issue in modern electrocatalysis. Traditional platinum-based catalysts are not viable in the long term and thus much effort has been focused on non-precious metal catalysts. Heteroatom doped and metal-heteroatom co-doped carbon materials have emerged as the main candidate for replacing the platinum-based catalysts. Different MN4 macrocycles, such as metal phthalocyanines and porphyrins, have been studied as promising materials to prepare electrocatalysts for ORR in alkaline media [1]. While the development of non-precious metal and non-metal carbon catalysts has gained a lot of attention recently, non-metal phthalocyanines are a less studied topic [2].In this work a novel catalyst material including multi-walled carbon nanotubes (MWCNT) and silicon phthalocyanine dichloride (SiPcCl2) was synthesised and the electrochemical activity towards the oxygen reduction reaction (ORR) in alkaline media was studied. Different ratios of phthalocyanine-to-nanotubes were pyrolysed at 800 °C. After optimising the ratio of phthalocyanine-to-nanotubes, the pyrolysis process was also carried out at different temperatures, but the results showed that the best temperature for pyrolysis is still 800 °C. ORR activity on SiPc/MWCNT catalyst was studied in 0.1 M KOH by employing rotating disc electrode method. Physical characterisation was carried out with X-ray photoelectron spectroscopy and transmission electron microscopy. The results showed successful incorporation of silicon and nitrogen into the carbon framework. We show that doping MWCNTs with a non-metal phthalocyanine creates a highly active ORR catalyst rivaling the activity of metal-based catalysts in alkaline conditions. This work clearly demonstrates that non-metal macrocyclic compound modified carbons, similar to the the SiPc/MWCNT can be used as alternative cathode catalysts for the metal-air batteries and alkaline membrane fuel cells.[1] Y. Liu, X. Yue, K. Li, J. Qiao, D.P. Wilkinson, J. Zhang, PEM fuel cell electrocatalysts based on transition metal macrocyclic compounds, Coord Chem Rev. 315 (2016) 153-177.[2] K.-K. Türk, K. Kaare, I. Kruusenberg, M. Merisalu, U. Joost, L. Matisen, V. Sammelselg, J.H. Zagal, K. Tammeveski, Oxygen electroreduction on zinc and dilithium phthalocyanine modified multiwalled carbon nanotubes in alkaline media, J. Electrochem. Soc. 164 (2017) H338-H344.

UV- Irradiation Induced Changes in Structural and Optical Characterization of Silicon Phthalocyanine Dichloride (SiPcCl2) Thin Films

In the current study, novel deposited SiPcCl2 thin films as organic semiconductor were experimentally investigated. The films were prepared using thermal evaporation technique on substrates of glass and quartz materials and then exposed to UV-irradiation from 60 min to 350 min. The molecular chemical composition of SiPcCl2 in powder form, as-deposited and ultraviolet irradiated films were analyzed using Fourier-transform infrared technique (FT-IR). The scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns confirmed the amorphous structure for deposited and UV-irradiated films. Furthermore, the indirect allowed transition with optical gap, Eopt. of 1.77 eV was reduced to 1.65 eV by exposing to ultraviolet rays for 350 min. Some of the significant optical parameters for as-deposited film such as: molar extinction coefficient, (ξmolar = 7430 mol/cm), strength of electronic dipole (q2 = 0.35A2) and strength of oscillator (f = 0.20) of the optical transitions have been estimated and also for irradiated films.

Structural characterization and optical parameter of silicon phthalocyanine dichloride thin films dependence with gamma ray radiation

Silicon phthalocyanine dichloride (SiPcCl2) thin films was prepared using thermal evaporation technique. The optical and structural properties of the films were examined before and after gamma irradiation process. X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Scanning electron microscope (SEM) investigated the structure of SiPcCl2. Moreover, optical properties were studied before and after irradiation. The optical band gap decreased from 2.44 eV to 2.09 eV after irradiation with 5 KGy. The dispersion parameters like the infinity ε∞, lattice εL dielectric constants, dispersion energy Ed, the ratio of carrier concentration to the effective mass N/m*, oscillator energy Eo were evaluated. Furthermore, the relation of volume energy loss functions VELF, the surface energy loss functions SELF, the real part ε1 and imaginary part ε2 of the dielectric constant with photon energy, hυ was analyzed.

Thermal annealing effect on the structural and optical characteristics of silicon phthalocyanine dichloride thin films

The crystal structure of silicon phthalocyanine dichloride (SiPcCl2) was studied using X-ray diffraction (XRD). The SiPcCl2 powder was polycrystalline and transformed to an amorphous form for pristine and annealed thin films. The prepared films were annealed at 363 K, 403 K, 543 K and 493 K for 2 h in a drying oven. The optical characteristics of these films were studied under normal light incidence in wavelength range from 190 to 2500 nm using spectrophotometry technique. The electronic transition type is an indirect allowed transition with optical and onset energy gaps of 1.92 eV and 1.25 eV, respectively. As the temperature rised, the defects gradually disappeared and the localized density of states tended to decrease; thus, the optical energy gap increased. The annealing effect on optical parameters, such as the real (ε1) and imaginary (ε2) parts of the dielectric constant, the volume energy loss function (VELF) and the surface energy loss function (SELF), was studied. The ratio between the free charge carrier concentration and the effective mass (N/m*), the lattice dielectric constant (εL), the infinite frequency dielectric constant (ε∞), the oscillator energy (Eo) and the dispersion energy (Ed) were calculated before and after thermal annealing.

Synthesis, structural characterization, and investigation on photophysical and photochemical features of new metallophthalocyanines

In this report, the 3,7,11-trimethyl-2,6,10-dodecatrien-1-ol group was substituted to the peripheral positions of the phthalocyanine macrocycle for obtaining copper (II) 4, cobalt (II) 5 and zinc (II) 6 phthalocyanine derivatives starting from the phthalonitrile derivative 3. This group was also axially substituted to the silicon (IV) phthalocyanine for the synthesis of silicon(IV) phthalocyanine 8 starting from silicon(IV) phthalocyanine dichloride 7 (SiPcCl2). The newly synthesized phthalocyanines 4–6 and 8 exhibited good solubility in tetrahydrofuran, ethyl acetate, CH2Cl2, N,N-dimethylformamide, diethyl ether, CHCl3, ethyl alcohol, DMSO, and acetonitrile. The novel compounds were structurally characterized by LC-MS/MS (for the phthalonitrile derivative 3), 1H NMR (for the compounds 3, 6 and 8), 13C NMR (for the compound 3), FT–IR, elemental analysis, UV–Vis spectroscopy (for phthalocyanines) and MALDI–TOF mass spectral data (for phthalocyanines). The aggregation behavior, photophysical and photochemical properties such as fluorescence lifetime and quantum yields, singlet oxygen and photodegradation quantum yields of 6 and 8 were explored in dimethylsulfoxide (DMSO) to the determination of the potential use of these novel phthalocyanines as photosensitizers in photodynamic therapy (PDT) applications. The newly synthesized zinc(II) phthalocyanine (6) showed high singlet oxygen generation in DMSO when compared to unsubstituted zinc(II) phthalocyanine that used the standard. The studied phthalocyanine complexes 6 and 8 exhibited moderate degradation under light irradiation. These results indicate that the studied phthalocyanines 6 and 8 can be a candidate as photosensitizers for PDT.

Axially phenoxy-derivative disubstituted phthalocyanine: synthesis, characterization and photophysical properties

We report the highly soluble axially disubstituted 4-(methoxymethyl) phenol silicon (IV) (1) phthalocyanine which was synthesized by the reaction of silicon phthalocyanine dichloride (SiPcCl2) with 4-(methoxymethyl)phenol. UV–Vis, FT-IR, 1H, 13C, NMR and mass spectrometry were used to characterize SiPc (1). Fluorescence quantum yield (spectral and photophysical) characteristics of SiPc (1) were investigated for various solvents. The obtained spectral and photophysical results indicated that the fluorescence quantum yields (ΦF) of SiPc (1) are both lower than unsubstituted ZnPc and SiPcCl2 in the solvents used which is not typical of silicon-phthalocyanines. The effects on optoelectronic and spectral properties of SiPc (1) of solvents and concentrations were investigated in detail. We obtained absorption band edge, maximum peak of absorbance, molar and mass extinction coefficients, refractive index, optical band gap, optical and electrical conductance of SiPc (1) for different solvents and concentrations. We obtained the refractive index values of SiPc (1) with many relationships. Also, we investigated the angles of incidence and refraction of SiPc (1). SiPc (1) exhibited semiconductor behavior in terms of optical band gap and can be used for photonic applications.

Axially substituted silicon(IV) phthalocyanine and its quaternized derivative as photosensitizers towards tumor cells and bacterial pathogens

Axially di-(alpha,alpha-diphenyl-4-pyridylmethoxy) silicon(IV) phthalocyanine (3) and its quaternized derivative (3Q) were synthesized and tested as photosensitizers against tumor and bacterial cells. These new phthalocyanines were characterized by elemental analysis, and different spectroscopic methods such as FT-IR, UV–Vis, MALDI-TOF and 1H NMR. The photophysical properties such as absorption and fluorescence, and the photochemical properties such as singlet oxygen generation of both phthalocyanines were investigated in solutions. The obtained values were compared to the values obtained with unsubstituted silicon(IV) phthalocyanine dichloride (SiPcCl2). The addition of two di-(alpha,alpha-diphenyl-4-pyridylmethanol) groups as axial ligands showed an improvement of the photophysical and photochemical properties and an increasement of the singlet oxygen quantum yield (ΦΔ) from 0.15 to 0.33 was determined. The photodynamic efficacy of synthesized photosensitizers (3 and 3Q) were evaluated with promising photocytotoxicity (17% cell survival for 3 and 28% for 3Q) against the cervical cancer cell line (HeLa). The photodynamic inactivation of pathogenic bacterial strains Streptococcus mutans, Staphylococcus aureus, and Pseudomonas aeruginosa suggested a high susceptibility with quaternized derivative (3Q). The both Gram-positive bacterial strains were fully photoinactivated with 11μM 3Q and mild light dose 50J.cm−2. In case of P. aeruginosa the effect was negligible for concentrations up to 22μM 3Q and light dose 100J.cm−2. The results suggested that the novel axially substituted silicon(IV) phthalocyanines have promising characteristic as photosensitizer towards tumor cells. The quaternized derivative 3Q has high potential for photoinactivation of pathogenic bacterial species.

A graphene-phthalocyanine hybrid as a next photoactive layer

Highly dispersible graphene was hybridized with a phthalocyanine derivative via covalent linkage to create a new type of donor-acceptor hybrid exhibiting photoinduced charge separation. Graphene is beneficial for the hybridization due to its easy functionalization and the unique electron accepting ability. A phthalocyanine (PC) derivative, pyrazine-based silicon phthalocyanine dichloride, possessing rich π-conjugated macrocycle was used for the electron donating purpose. The hybrid molecule showed a significant decrease in fluorescence of π-conjugated PC, implying an efficient photoinduced charge transfer occurring within the covalently-linked molecular structure consisting of “donor-acceptor”. The graphene-PC hybrid molecule has also been demonstrated as an active layer material in organic photovoltaic device as well. Thus our results indeed underline the efficacy of the molecular level heterojunction of the covalently linked graphene-PC molecule in a single cell and will open new opportunities ahead for active layers research to go beyond conventional bulk-heterojunction (BHJ).

Synthesis of water soluble axially disubstituted silicon (IV) phthalocyanines with alkyne & azide functionality

Phthalocyanines (Pcs) are a class of photosensitizers (PSs) with a strong tendency to aggregate in aqueous solutions, which has a negative influence on their photosensitizing ability for photodynamic therapy. Four new axially disubstituted, non-aggregated silicon phthalocyanines (SiPcs), containing azide or alkyne functional groups have been synthesized and characterized. The method of synthesis is based on the reaction of silicon phthalocyanine dichloride with variable length poly(ethylene glycol) (PEG) chains in the presence of NaH. All synthesized dyes are highly soluble in alcohols, THF, CH2 Cl2, acetone, DMF and other common polar organic solvents, with the PEGylated silicon phthalocyanines (SiPcs) also being soluble in water. Photophysical and electrochemical properties of the dyes have been investigated. The presence of alkyne or azide groups in the phthalocyanine dyes, coupled with their high aqueous solubility, make these compounds useful as building blocks in copper catalyzed Huigsen azide-alkyne cycloaddition reactions (i.e. click chemistry).

Novel axially carborane-cage substituted silicon phthalocyanine photosensitizer; synthesis, characterization and photophysicochemical properties

The novel axially dicarborane substituted silicon (IV) (SiPc-DC) phthalocyanine was synthesized by treating silicon phthalocyanine dichloride SiPc(Cl)2 (SiPc) with o-Carborane monool. The compound was characterized by mass spectrometry, UV–Vis, FT-IR, 1H and 11B Nuclear Magnetic Resonance Spectroscopy (NMR). Spectral, photophysical (fluorescence quantum yield) and photochemical (singlet oxygen (ΦΔ) and photodegradation quantum yield (Φd)) properties of the complex were reported in different solutions (Dimethyl sulfoxide (DMSO), Dimethylformamide (DMF) and Toluene). The results of spectral measurements showed that both SiPc and carborane cage can have potential to be used as sensitizers in photodynamic therapy (PDT) and boron neutron capture therapy (BNCT) by their singlet oxygen efficiencies (ΦΔ=0.41, 0.39).

Synthesis of Silica Vesicles with Small Sizes and Reduced Aggregation for Photodynamic Therapy

Abstract Silica vesicles (SVs) with a diameter of 30 nm and reduced aggregation have been successfully synthesized using mixed triblock copolymer surfactants as the structure-directing agents, tetraethyl orthosilicate and tetrapropyl orthosilicate as mixed silica sources. Silicon phthalocyanine dichloride (SiPC) has been loaded into SV, significantly enhancing the delivery and photodynamic therapy efficiency of SiPC into cancer cells.

Novel phthalocyanine and PEG-methacrylates based temperature-responsive polymers for targeted photodynamic therapy

A novel multi-targeting nanocarrier (SiPc-polymer) for photodynamic therapy (PDT) has been successfully polymerized via the incorporation of silicon(IV) phthalocyanine dichloride (SiPcCl2) to the thermoresponsive PEG-methacrylates based polymers. The resulting SiPc-polymer was characterized by 1H NMR spectroscopy, GPC, UV-Vis and elemental analysis. The lower critical solution temperature (LCST) of the SiPc-polymer can be easily controlled via changing the ratio of the applied monomers, di(ethylene glycol) methyl ether methacrylate (DEGMEMA), oligo(ethylene glycol) methyl ether methacrylate (OEGMEMA, Mw = 475 g mol−1) and 2-hydroxyethyl methacrylate (HEMA). The synthesized polymers assemble into nanoparticles (70 nm) in aqueous solution, which normally exhibits permeation and retention (EPR) effects, the thermo-responsive features provide the possibility to selectively accumulate at a maligned tissue site upon mild heating and high singlet oxygen quantum yields (ΦΔ = 0.55) are obtained which guarantee the controlled liberation of reactive oxygen species upon light irradiation. This provides a simple way to synthesize a multi-targeting drug carrier system for PDT.

Highly photostable silicon(IV) phthalocyanines containing adamantane moieties: synthesis, structure, and properties

Two new axially disubstituted silicon(IV) phthalocyanines 1 and 2 have been synthesized by treating silicon phthalocyanine dichloride with 1-adamantanemethanol or 1-adamamtaneethanol, respectively. The crystal structure of compound 2 has been characterized by X-ray diffraction analysis. Both compounds are efficient singlet-oxygen generator with a quantum yield of 0.40–0.43. With two rigid bulky adamantane moieties at the axial positions, these phthalocyanines not only are essentially non-aggregated in common solvents, but also exhibit a high photostability. They are about 100 times more stable than zinc phthalocyanine under the same irradiation conditions. With the goal of enhancing the biocompatibilities, interactions and conjugations of these two compounds with bovine serum albumin have also been investigated.

Orientation of Si phthalocyanine investigated by X‐ray absorption spectroscopy and molecular orbital calculation

AbstractWe have investigated the orientation effect of silicon phthalocyanine dichloride evaporated on the highly oriented pyrolytic graphite (HOPG) surfaces using linearly polarized synchrotron radiation. Polarization angular dependences of Si 1s and Cl 1s near‐edge X‐ray absorption fine structure (NEXAFS) spectra were observed and compared with theoretical calculations based on equivalent core (Z + 1) approximation using the Hartree‐Fock molecular orbital method. The calculated properties are in agreement with the experimental spectra in symmetry, intensity and energy position. The intensities for the lowest energy peaks observed at both Si and Cl edges are enhanced when X‐ray electric field vector (E) is perpendicular to the surface. We assigned these peaks to out‐of‐plane transition into σz*(SiCl) final state orbital. We concluded that phthalocyanine plane is oriented parallel to the surface. Copyright © 2010 John Wiley & Sons, Ltd.