Heteroaggregation between porphyrin and phthalocyanine bearing oppositely charged substituents

Heteroaggregates composed of cationic porphyrin, meso-tetra(p-trimethylamino)-porphyrin iodide, its zinc complex and anionic phthalocyanine sodium hydroxygallium 4,4',4",4"'-tetrasulfonated phthalocyanine have been investigated by absorption and fluorescence spectroscopy. It has been found that both free base cationic porphyrin and its zinc complex can form very stable heterodimers with anionic phthalocyanine in water, methanol and dhnethylfonnamide. The stability of the aggregate depends on the polarity as well as the ligation ability of the solvent. No evidence of higher aggregates was detected. Besides axial coordination, steric hindrance which influence the relative orientation of the macrocycles are considered.     

Second harmonic generation at the interface of copper tetra-tert-butyl phthalocyanine Langmuir-Blodgett film/metal

As one of the most primitive nonlinear optical phenomena, optical second harmonic genera-tion (SHG) has been investigated for half a century and it has become a very useful spectroscopic tool in the study of surface and interface[1—3]. It was theoretically shown that the SH signal cannot be generated in a centrosymmetric system. However, the generation of SH signal from the centro-symmetric molecules such as fullerene (C60) and CuPc has been detected[4—7]. In our recent ex-periments, an …     

Thin film processing of axially modified phthalocyanine derivatives

A new class of hydroxyl terminated silicon phthalocyanine (SiPc) derivatives was prepared by capping dihydroxy SiPc with a variety of compounds containing two or more hydroxyl groups. The unique feature of these polyhydroxy SiPc derivatives is their function as crosslinkers that allows their processability into polyurethane films on reacting with isophorone diisocyanate. The films possess high impact resistance, thermostability at 125°C for over 10 h, and low absorption in the visible region. Solid polymeric films incorporating over 20% (w/w) of Pc rings were prepared without phase segregation. The kinetic parameters of polymerization, such as reaction conversion versus time and temperature, heat of reaction (ΔH), activation energy (ΔE), and reaction order (n) were investigated. Some of the polyhydroxy SiPc derivatives exhibit very high solubility in common organic solvents and possess adequate optical transparency for use as nonlinear optical materials in vision protection against laser light. © 1996 John Wiley & Sons, Inc.     

A cobalt(II) phthalocyanine with indole substituents: formation,characterization and electrocatalytic studies

Herein, we report the formation of a new cobalt(II) phthalocyanine (CoPc) containing peripheral tetra-substituted indole (CoPc-ind, 2) moieties. The derivatized phthalonitrile, 4-(indole-4-oxy)phthalonitrile (1) as well its corresponding metal complex was characterized by NMR (for 1), IR– and UV–Vis spectroscopy as well as TOF mass spectrometry and elemental analysis (for 2). The electrochemical properties of the N₄-macrocyclic metal complex were investigated using cyclic- and square-wave voltammetry as well as corroborated by UV–Vis spectroelectrochemistry. The CoPc was electrodeposited onto the surface of a Pt working electrode followed by the immobilization of multiwalled carbon nanotubes (MWCNTs) onto the modified working electrode surface. The electrocatalytic activity of the resultant modified electrode toward dopamine revealed a lower ΔE value of 80?mV versus Ag|AgCl for the modified (2-MWCNTs) Pt electrode compared to the bare Pt electrode (ΔE?=?280?mV vs. Ag|AgCl). The diffusion- and convection-controlled electron-transfer kinetics of the chemically modified electrode were evaluated by chronoamperometry and rotating disk electrode techniques. Electrochemical impedance spectroscopic studies revealed that the 2-MWCNTs Pt electrode had a lower charge-transfer resistance and a higher apparent electron-transfer rate constant.     

The Mixed LB film of Crowned Phthalocyanine and Picrate

Phthalocyaninesareexcellentpigmentswithgo0dthermalandchemicalstability.TheypossessanumberofcharacteristicsthatmakethemsuitableforaPplicahonsinthefieldofmolecularelectronicsl.LBfilmsofphtalocyanineshavebeenwidelystudiedinthepastdecades2'3.PreviouslywereportedthefabricationofmixedLBfilmsofanamphiphilicphthalocyanineandhydrophobicporphyrin4.Herewereportthedepositionandcharacterizationofthemixedfilm0fphthalcyaninehavingapendantcr0wnethergroupandnacceptor(picrate)basedonhost-guestcomPlexation.Mo…     

Directed motion of a polyelectrolyte micelle along tethered chains of oppositely charged polyelectrolyte brush

The complexation of different single polyelectrolyte (PE) micelles formed by linear diblock copolymers with oppositely charged brushes with varying grafting densities and charge content was studied by means of molecular dynamics simulations using the primitive model. We found that all micelles perform a directed motion along the vertical z axis on the grafted surface where they trapped while on the other axes the motion is restricted in a circle in which the diameter decreases with the increase of the hydrophilic length of the linear diblock copolymer. The motion of micelles is characterized as super diffusion inside brushes with low densities and low charge content. At high grafting densities and charge content the diffusion becomes Fickian or slightly subdiffusive. The number of the absorbed brush chains on the micelle corona increases almost monotonically with the increase of brush grafting density or with the decrease of charge content. The distance from the surface in which the micelle is trapped can be controlled by the charge density along the grafted PE chain. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 621–631     

Multi-electron transfer in composite phthalocyanine thin films: structure and electrochromic properties

Both sequentially deposited double-layered and codeposited composite thin films were prepared by using two kinds of phthalocyanines. The structure and the electrochromic property of these thin films were compared with those of simple phthalocyanine films. The structures of the films were analyzed by scanning electron microscopy (SEM), X-ray diffrction (XRD) and electron spin resonance (ESR) spectra. From the viewpoint of morphology and crystallinity, codeposited thin films have the same structure as the simple one, having sharp peaks at ca. 2θ=7.0° in the XRD pattern and narrow crystal grains in SEM photographs. ESR measurements have revealed that phthalocyanine molecules disperse very well in the codeposited thin films in a molecular level in comparison with the physical mixture of phthalocyanine powders. This high dispersibility of the molecules in the codeposited thin films can play a role to improve the reversibility in the electrochromism. Thus, the reversibility of the phthalocyanine, which shows irreversible electrochromism in the simple film form, can be improved by the codeposition with another phthalocyanine with reversible electrochromism. In contrast, sequentially deposted double-layered thin film gives completely different results. The electrochromism of the double-layered film depends on the property of the simple phthalocyanine thin film which is in contact with the substrate.     

Preparation of ultrathin membranes by layer-by-layer (LBL) deposition of oppositely charged inorganic colloids

Nanofilms were prepared by alternating deposition of Mg–Al (2:1) NO ₃ ⁻ layered double hydroxide (LDH), hectorite and silica particles present study. The charge density of the oppositely charged materials strongly affect film properties like thickness and ordering. The specific charge of the colloidal particles was measured with the particle charge detector. The sequential build up of the thin films was followed by spectrophotometry and X-ray diffraction (XRD). The surface morphology of the formed multilayers was characterized and film thickness determination was performed by atomic force microscopy. The influence of the charge density of hectorite and silica particles on the LDH/hectorite, LDH/silica film thickness was studied. The results reveal that the LDH concentration has a significant effect on the film thickness while the hectorite and silica concentration were not important. Films prepared from the different types of negatively charged inorganic particles in the same concentration range (0.25–1.0%) have similar thickness because of the much higher surface charge relative to the LDH lamellae.     

Cobalt phthalocyanine catalyzed aerobic oxidation of secondary alcohols: an efficient and simple synthesis of ketones

A variety of activated and non-activated secondary alcohols have been efficiently oxidized to their corresponding ketones in excellent yields with molecular oxygen using cobalt phthalocyanine as catalyst in the presence of powdered potassium hydroxide.     

Molecular dynamics simulation of surface morphology and thermodynamic properties of polyaniline nanostructured film

To develop predictive models in nanostructured films, there is an ongoing research to validate molecular dynamics (MD) simulation results with experimental data. The morphology and surface topography of polyaniline (PANI) nanostructured film coated on a TiO₂ nanocrystalline surface were investigated by scanning electron microscopy and atomic force microscopy, respectively. The atomistic model of the simulated PANI was generated using energy minimization with a condensed‐phase optimized molecular potential for atomistic studies force field function to reach a thermodynamic equilibrium state. Various parameters of PANI such as density, energy, cavity size, and free volume distributions are calculated. MD simulation has also been used to obtain specific volume (V) as a function of temperature (T). It is demonstrated that this V–T curve can be used to determinate glass transition temperature T_g, reliably. Although experimental data available for the PANI film are very limited, simulation results such as density and T_g are in good agreement with the experimental values reported in the literature. Comparison of the surface topography of PANI demonstrates a reasonable trend between atomic force microscopy image analysis and the MD simulation results at various temperatures. Copyright © 2014 John Wiley & Sons, Ltd.     

Double-decker phthalocyanine complex: Scanning tunneling microscopy study of film formation and spin properties

We review recent studies of double-decker and triple-decker phthalocyanine (Pc) molecules adsorbed on surfaces in terms of the bonding configuration, electronic structure and spin state.     

化学水浴沉积法制备CdSe薄膜

CdSe是直接跃迁宽带隙的II-VI族化合物半导体,具有立方和六方两种结构,以及与太阳谱中可见光波段相适宜的带宽(<1.7ev),是制作异质结太阳电池和光电化学太阳电池的重要原料[1,2].     

Mixed brushes consisting of oppositely charged Y-shaped polymers in salt free,monovalent, and divalent salt solutions

The conformation and the internal stratification of mixed brushes formed from oppositely charged Y(−) and Y(+)-shaped chains in salt free, monovalent, and divalent salt solutions were studied by means of molecular dynamics simulations using the primitive model. Scaling relations of mixed brush height with respect to the grafting surface per chain, the ratio of the total positive to the total negative charge of polyelectrolyte chains, and salt concentrations were obtained. The simulations predicted that mixed brushes show a unique response to divalent salt (1:2) solutions. For symmetric brushes having the same spacer lengths, number of chains and charged units fractions the increase of the salt concentration leads to the enrichment of the outer brush surface with Y(+) units and the lamella microphase separation. For asymmetric brushes in high salt concentration cylindrical domain microphases are formed.     

Fabrication of a covalently attached multilayer film electrode containing cobalt phthalocyanine and its application as a potentiometric sensor of iodide ion

Construction of a highly stable covalently attached multilayer film electrode containing cobalt phthalocyanine was achieved by UV irradiation of ionic self-assembled multilayer films of diazo-resins (DAR) and cobalt phthalocyanine tetrasulfonic acid (CoTsPc) tetrasodium salt. The modified electrode had good potentiometric response to iodide ion. The potentiometric response was independent of the pH of the solution between pH 2.5 and 6.0, while it was dependent on the nature of the buffer media. The modified electrode had a linear dynamic range between 4.7×10⁻⁶ M and 0.1 M with a Nernstian slope of 58.8 mV per decade and a detection limit of 3.5×10⁻⁶ M in acetate buffer (0.1 M, pH 4.6). The modified electrode also exhibited a fast response, good stability and repeatability.     

In-situ fluorescence imaging of sol-gel thin film deposition

Pyranine was used as a fluorescence probe to monitor the chemical evolution in-situ during thin film deposition by the dip coating process. The sensitivity of the pyranine luminescence to protonation/deprotonation effects was used to quantify changes in the water/alcohol ratio in real time within the depositing film as the substrate was withdrawn from the coating reservoir. The spatially resolved spectral results clearly showed that preferential evaporation of alcohol occurred with increasing distance from the reservoir and that the maximum water content reached rather high values near the drying line. Correlation of the luminescence results with the interference pattern of the drawn films allows the solvent composition in the film to be mapped as a function of film thickness. These experiments demonstrate for the first time that luminescent organic molecules may be applied to the processing science of sol-gel thin film deposition.     

Effects of porphyrin substituents on film structure and photoelectrochemical properties of porphyrin/fullerene composite clusters electrophoretically deposited on nanostructured SnO2 electrodes

We have systematically examined the substituent effects of meso-tetraphenylporphyrins on film structures and the photoelectrochemical properties of the composite clusters of free-base porphyrin and C(60) electrophoretically deposited on nanostructured SnO(2) electrodes. The photocurrent generation efficiency was found to correlate with the complexation ability of the porphyrin for C(60). Basically, the incident photon-to-current efficiency (IPCE) value was increased with increasing relative amounts of the porphyrin versus C(60) in the films. The unique molecular arrangement of the porphyrin with the simple, specific substituents (i.e., methoxy groups at the meta-positions of the meso-phenyl rings of tetraphenylporphyrins (3,5-OMeTPP; TPP=tetraphenylporphyrin)) and C(60) on SnO(2) electrodes resulted in the largest IPCE value (ca. 60 %) among this type of photoelectrochemical device. The rapid formation of the composite clusters and microcrystals from the combination of 3,5-OMeTPP and C(60) in a mixed solvent is unique as the association is accelerated by intermolecular interactions (i.e., hydrogen-bonding and CH-pi interactions) between the methoxy groups of the porphyrins and the porphyrin/C(60), in addition to the pi-pi interactions between the porphyrins/C(60) and C(60) molecules. Both the films and single crystals composed of the porphyrin and C(60) exhibited remarkably high electron mobility (7x10(-2) and 0.4 cm(2) V(-1) s(-1)), which is comparable to the value for highly efficient bulk heterojunction solar cells. Our experimental results have successfully demonstrated the importance of nanostructured electron- and hole-transporting pathways in bulk heterojunction solar cells. Such a finding will provide basic and valuable information on the design of molecular photovoltaics at the molecular level.     

Investigation of adsorbed polymer layers by flocculation of oppositely charged sols III. Effect of molecular mass of polymers

The stabilizing effect of water-soluble neutral polymers with different chemical structure and relative molecular mass on AgI sol has been studied. It was shown that the stabilizing effect of the polymers used is independent of the relative molecular mass of the polymer when equal amounts of the adsorbed polymers are compared with each other as stabilizers. The high stabilizing effect of polymers with high relative molecular mass is presumably due to the larger adsorbed amount.Among polyvinyl alcohol, polyvinyl pyrrolidone and methylcellulose, polyvinyl pyrrolidone exhibits the smallest stabilizing layer thickness at equal adsorbed amounts. According to our earlier results this is due to the fact that the polyvinyl pyrrolidone shows the strongest affinity for AgI surfaces, forming short loops or tails.     

Photophysical and photochemical properties of tetrasulfonated silicon and germanium phthalocyanine in aqueous and non-aqueous media

The photophysical and photochemical properties of tetrasulfonated silicon and germanium phthalocyanine (SiPcS₄ and GePcS₄) in aqueous solution (phosphate-buffered saline (PBS) solution, pH 7.4) (in the presence and absence of cremophore EL (CEL)) and in dimethylsulphoxide (DMSO) were studied. The complexes have intense absorption in the visible/near-IR region though they highly aggregate in aqueous solution with a dimerization constant of 2 × 10⁴ dm³ mol⁻¹. The fluorescence excitation spectra however have only one band suggesting that only the monomer fluoresces. Both the quantum yields of the triplet state (Φ_T) and the triplet lifetimes (τ_T) were found to be higher in DMSO compared to in aqueous solution. Aggregation is hindered by addition of cremophore EL in aqueous solution and this induced disaggregation caused an increased Φ_T and τ_T probably due to the reduced interaction of the phthalocyanines with the aqueous medium in the presence of CEL.     

Anomalous phase behavior of water-soluble polyelectrolyte and oppositely charged surfactants

Aqueous mixtures of anionic surfactants with cationically substituted quaternary ammonium derivatives of hydroxyethylcellulose, JR and LR series, were investigated by several techniques. On adding sodium dodecyl sulfate (SDS) to a polyelectrolyte solution, phase separation with precipitation occurs in a co-operative way, and redissolution of precipitation is observed at the critical micelle concentration (CMC) of SDS. This is due to admicelle formation on the polyelectrolyte. The phase separation for the two-headed anionic surfactant systems is also seen, while the concentration where this takes place is near the CMC of the surfactant. This is remarkable in the case of the triethanolamine cocoyl glutamate (TCG)–JR 400 system, in which TCG has a CMC over 1 order of magnitude smaller CMC than that of SDS. Surface tension and the dynamic light scattering measurements show the existence of not only electrostatic interaction between the cationic polyelectrolyte and the two-headed anionic surfactant but also intraction between the adsorbed polymers. The scaling analysis of the precipitation line of the surfactant with polyelectrolyte concentration elucidates that one molecule of TCG can neutralize approximately two charges on JR 400. Received: 9 February 1999 Accepted in revised form: 23 June 1999     

Dynamic quartz crystal impedance measurements of polyvinylferrocene film deposition

Dynamic crystal impedance measurements were used to study the electrochemically-driven deposition of polyvinylferrocene (PVF) films from dichloromethane solutions of PVF onto Au electrodes of a quartz crystal microbalance. Under all the conditions studied, the PVF films were non-rigid, to an extent that depended upon several experimental factors. Films deposited from solutions containing perchlorate salts of tetraalkylammonium salts departed less from rigidity than those deposited under otherwise identical conditions from tetrafluoroborate media. In contrast, the use of different tetraalkylammonium cations, or the use of a potential sweep vs. a potential step from 0 V to the deposition potential (0.7 V), made no significant difference. The departure from rigid characteristics varied with coverage. For the interval of time during deposition that the coverage was 10–160 nmol cm⁻² (of monomeric ferrocene units), the films showed no additional departure from rigidity. On the basis that the upper figure corresponds closely to a “monolayer” of terminally attached chains of mean length, we attribute this behaviour to the presence of a dense film, within which chain motion is considerably restrained.