Octa-substituted Metal-free Phthalocyanine Research Articles

The synthesis of symmetrical peripheral and non-peripheral octa-substituted metal-free phthalocyanines: simpler, better, faster, cheaper

The synthesis of symmetrical peripheral and non-peripheral octa-substituted metal-free phthalocyanines: simpler, better, faster, cheaper

Synthesis and electrochemistry of new octa-substituted metal-free and metallophthalocyanines

The synthesis and characterization of metal-free (H2-Pc) and metal-containing (Zn, Co, and Cu) derivatives of a symmetrically octa-substituted phthalocyanine derived from 4,5-bis[2-(phenylthio)ethoxy]phthalonitrile were carried out by microwave irradiation. The electrochemical properties of the metal-free phthalocyanine 4 and metallophthalocyanine complexes 5 and 6 were investigated by cyclic voltammetry and differential pulse voltammetry. We have previously investigated the electrochemical properties of the tetra substituted 2-(phenylthio)ethoxy phthalocyanines. The reduction potential of the octa-substituted metal-free phthalocyanine shifted to more negative potential as a result of the electron donating of the 2-(phenylthio)ethoxy groups on the periphery compared to those of tetra substituted. The H2Pc and ZnPc demonstrated ligand-based electron transfer processes, while CoPc complex has a metal-based reduction process. Similar aggregation behavior was observed for octa-substituted phthalocyanines. The compounds were characterized using IR, 1H NMR, 13C NMR, elemental analysis, and MS spectral data.

Thin films of asymmetrically substituted “ ABAB-Type” indium phthalocyanine chloride: Preparation, structural characterization and optical properties

A synthetic route to the asymmetric octasubstituted metal-free phthalocyanines H 2Pcs ( 3–8) has been developed. They contain a combination of 2(3),16(17)-Tetra( 2-ethyl-1-hexyl) and 9(10),23(24)-tetra( n-hexyl) as substituent groups in the peripheral positions. Thin films of the target asymmetric substituted “ ABAB-Type” indium phthalocyanine chloride complex InPcCl 9, have been also fabricated for the first time, with different thickness (105–350 nm) using thermal evaporation technique. The structural and optical properties of the films have been investigated. The material in powder form showed a polycrystalline nature with triclinic structure. Miller indices, hkl, values for each diffraction line in X-ray diffraction (XRD) spectrum were calculated. The as-deposited films exhibited also a crystalline nature with a preferred orientation of growth. The scanning electron microscope showed the nano-structure property of the deposited films. The optical properties of the films are studied by the spectrophotometric measurements of the transmittance, T and the reflectance, R determined at the normal incident of the light in the spectral range 200–2500 nm. The refractive and absorption indices of the films are calculated and are found to be independent of film thickness of 105–350 nm. Different dispersion and absorption parameters are determined for the films.

DFT study of structure, IR and Raman spectra of [formula omitted] and [formula omitted] dendrimers built from octasubstituted metal-free phthalocyanine core

The IR and Raman spectra of P 0 ′ and P 4 ′ dendrimers built from an octasubstituted metal-free phthalocyanine core with oxybenzaldehyde terminal groups have been recorded. The phthalocyanine core was used as a probe for analyzing the properties of the internal structure. The structural optimization and normal mode analysis were performed for P 0 ′ dendrimer on the basis of the density functional theory (DFT). It was found that the P 0 ′ molecule exists in a stable conformation with planar phthalocyanine core. The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. The experimental IR spectra of P 1 dendrimer were interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The difference IR and Raman spectra of molecules built from the thiophosphoryl and phthalocyanine cores with the same repeating units and terminal groups were studied in order to underline the role of the core functionality on the dendrimer architecture.

IR spectroscopy investigation using DFT analysis on the structure of P1 phosphorus dendrimer built from octasubstituted metal-free phthalocyanine core

The IR spectra of P 1 phosphorus dendrimer built from an octasubstituted metal-free phthalocyanine core have been recorded in the region 4000–400 cm −1. Besides the phthalocyanine core, P 1 possess also eight C 6H 4–CH N–N(CH 3)–P(S) arms and terminal P– Cl groups. The optimized molecular geometry, frequency and intensity of the IR bands have been calculated using density functional theory (DFT). The P 1 molecules exist in a stable conformation with planar C 6H 4–CH N–N(CH 3)– fragments and phthalocyanine core. The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. The experimental IR spectrum of P 1 dendrimer was interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The difference IR spectra of molecules built from the thiophosphoryl, cyclotriphosphazene, and phthalocyanine cores with the same repeated units and terminal groups were studied in order to undermine the role of the core functionality on the dendrimer architecture.

Octasubstituted Metal-Free Phthalocyanine as Core of Phosphorus Dendrimers: A Probe for the Properties of the Internal Structure

The synthesis of a new family of phosphorus dendrimers built from an octasubstituted metal-free phthalocyanine core is described up to generation 5. This core is used as a sensor and a probe for analyzing the properties of the internal structure and the influence of each structural part (core, branches, surface) upon the whole structure. UV-visible spectra show both a hyperchromic and bathochromic effect on the Q-bands with increasing generation, indicating that the chromophore is more isolated, and that the dendritic shell mimics a highly polar solvent. There is no evidence for aggregation, except for generation 0, showing again the isolation of the core. However, the dendritic shell is permeable to aqueous acids and bases, as demonstrated by the reversible splitting of the Q-band in an acidic medium (neutral form of the phthalocyanine) and the single Q-band in a basic medium (dianionic form), even for generation 4. The fluorescence quantum yield for the neutral form increases with increasing generation. The dianionic form of generation 0 is poorly fluorescent, whereas generations 3 and 4 (G3 and G4) exhibit better fluorescence. The cores of G3 and G4 are highly sensitive optical sensors for H3O+ and OH-. These experiments are carried out in THF/water mixtures, and the influence of water on the structure has been checked. The hydrodynamic radius of generation 4 is measured by NMR diffusion (pulse gradient spin-echo) experiments. R(H) varies from 35.4 A at 4 mol % of water to 32.5 A at 64 mol % of water in THF, indicating the hydrophobic nature of these dendrimers.

Tuning the maximum absorption wavelengths of phthalocyanine derivatives

A new series of low-symmetry octasubstituted metal-free phthalocyanines with the general formula H 2 N x P β4− x ( OBu )8 ( x = 0-4) were synthesized by mixed condensation of two different substituted precursors (4,5-dibutoxy- phthalonitrile and 1,4-dibutoxy-2,3-dicyanonaphthalene). Their electronic absorption spectra and MALDI-TOF-MS were investigated. The regiospecific, nonlinear and linear substituent effects of alkoxyl groups on the positions of the Q-bands of phthalocyanines with different substituent groups at different peripheral positions were systematically investigated. The results could provide a guide to the tuning of Q-band absorptions of phthalocyanine derivatives.

Inclusion phenomenon in mixed floating layers containing phthalocyanines

UV-vis absorption spectra of floating layers of octa-substituted metal-free phthalocyanines (AmPc) mixed with stearic acid or calix(4)resorcinarene derivatives (CA) were studied during monolayer compression. Most of the mixed floating layers, as well as those of the pure AmPc compounds, show characteristic spectra typically attributed to the AmPc condensed state, even at zero surface pressure. These results indicate the formation of aggregates of AmPc molecules on the water surface immediately after spreading. However mixed AmPc/CA floating layers with the molar ratios less than 1:2 show some spectral transformation at high values of surface pressure, which can be interpreted in terms of molecular rearrangement. Isolated AmPc molecules are thought to have formed due to their inclusion within the CA matrix.

An interpretation of the structure of Langmuir-Blodgett films of octa-substituted metal-free phthalocyanine molecules from optical spectra

An interpretation of the structure of Langmuir-Blodgett films of octa-substituted metal-free phthalocyanine molecules from optical spectra

An interpretation of the structure of Langmuir-Blodgett films of octa-substituted metal-free phthalocyanine molecules from optical spectra

Abstract Ultraviolet-visible absorption spectra of Langmuir-Blodgett (LB) films of octa-substituted metal-free phthalocyanine molecules are decomposed into Gaussian-Lorentzian components in order to compare the in-plane molecular arrangements of the two groups of the compounds with short and long alkyl chains. LB films of long-chain molecules represent the Davydov splitting of the Q band, which corresponds to the ‘herringbone’ molecular structure and the angle between the molecules is estimated to be 75°. For short-chain molecules, the largely broadened ‘blue’ component of the Davydov doublets is suppressed and this can be explained by the domination of an anisotropic stack-like molecular arrangement in LB films.

Surface plasmon resonance studies on Langmuir-Blodgett films of novel octa-substituted metal-free phthalocyanine molecules

Abstract The surface plasmon resonance technique is employed to characterize Langmuir-Blodgett (LB) films of novel amphiphilic octa-substituted metal-free phthalocyanine molecules. The refractive index nc is determined as a function of film thickness by fitting the experimental reflected intensity data to the exact Fresnel reflection formula. The angle of resonance is changed by about 0·33° corresponding to a change in the phase velocity of 1·4 × 106 m s-' for each additional monolayer. A value of 1·6 for nc is believed to be reasonable in the light of data available for other phthalocyanine compounds. The monolayer thickness is estimated to be 1·7 nm and the molecular planes are believed to be stacked at an angle of 47·7° to the substrate. The inner radiation arising from the LB coating of phthalocyanine molecules is found to be ten times greater than radiation damping, contributing significantly to the reduced depth of resonance.

Further optical studies on Langmuir-Blodgett films of octa-substituted metal-free phthalocyanines

Ellipsometry and optical spectroscopy in the ultraviolet-visible (UV-vis.) and infra-red ranges were used to study the correlation between structure and optical properties of Langmuir-Blodgett (LB) films of octa-substituted metal-free phthalocyanines containing different alkyl chains. The thickness and refractive index of LB films and the orientation of phthalocyanine moieties in the monolayer were obtained from ellipsometric measurements and then data were compared with those from Π A isotherms of the floating layer. UV-vis. absorption spectra of LB films of the molecules show Davydov splitting of the Q band. Small changes in alkyl length lead to significant changes in the Q-band shape. The optical characteristics of monolayers are found to be different from those of multilayer films.

Third-order Nonlinear Optical Properties of Octa-substituted Metal-free Phthalocyanine Thin Films

Third-order nonlinear optical susceptibility, X (3) of symmetrically octa-substituted metal-free phthalocyanine thin films measured by the third-harmonic generation technique are reported. The metal-free phthalocyanine has been found to show a X (3) (-3ω; ω,ω, ω) value as large as 7.73 x 10 -12 esu at 1.80 μm. The figure of merit, X (3) /α was estimated to be 4.17 x 10 -17 esu cm at 1.05 μm and 6.97 x 10 -16 esu cm at 1.65 μm. Both linear and third-order optical properties of liquid-crystalline metal-free phthalocyanines are discussed.