Photoelectric, nonlinear optical, and photorefractive properties of polymer composites based on supramolecular ensembles of Ru(II) and Ga(III) complexes with tetra-15-crown-5-phthalocyanine

Techniques of the production of polymer nanocomposites based on tetrapyrrole compounds with photoelectric, nonlinear optical, and photorefractive properties are considered. Supramolecular ensembles of Ru(II) and Ga(III) complexes with tetra-15-crown-5-phthalocyanine are found to form upon the deposition of thin films from tetrachloroethane solutions that have undergone several cycles of heating followed by slow cooling. The surface formation of supramolecular ensembles is studied with the use of atomic force microscopy. The assemblage is found to give rise to photoelectric and photorefractive sensitivity in the near-infrared range (measurements were carried out at 1064 and 1550 nm). The quantum yield of thermalized electron-hole pairs at 1064 nm in composites of polyvinyl carbazole and assembled Ga(III) complexes is 20 times as high as that in composites based on Ru(II) complexes. The largest two-beam coupling gain coefficient at 1064 nm (Γ = 120 cm^?1 at E ₀ = 120 V/μm) was also observed for the Ga(III)-complex-containing composite. The third-order dielectric molecular susceptibility measured in tetrachloroethane solutions of the complexes weakly depends on the nature of the central atom and its axial neighborhood and falls in a range of γ = 4?5.2 × 10^?32 esu.     

Photorefractive polymer composites based on ruthenium (II) tetra-15-crown-5-phthalocyanate axially coordinating ethylisonicotinate molecules photosensitive in telecommunication range

Polyvinylcarbazole layers containing ruthenium (II) tetra-15-crown-5-phthalocyanate axially coordinating ethylisonicotinate molecules are found to have photoelectric and photorefractive sensitivity at 1550 nm. The effect is determined by the formation of supramolecular ensembles with the electronic optical absorption and photoelectric sensitivity in the near IR range up to 1600 or 1700 nm and nonlinear optical properties. A photorefractive two-beam coupling gain coefficient Γ measured at 1550 nm increases with an increase in the Ru(II) complex content in the polymer layer and equals 25 cm⁻¹ at 6 wt %. The difference between the coupling gain and absorption coefficients (the actual gain coefficient) is Γ − α = 19 cm⁻¹. Additionally introducing 3 wt % C₆₀ fullerene into the layer does not change the characteristics, but the subsequent preirradiation (irradiation of the whole layer with a 633-nm laser beam in a range of the optical absorption of C₆₀ before recording photorefractive curves) results in an increase in the gain coefficient at 1550 nm up to Γ = 48.3 cm⁻¹ and, hence, in Γ − α = 42.3 cm⁻¹. A time constant of the diffraction grating formation is about τ = 0.8 s.     

Theoretical study on the second-order nonlinear optical properties of gold (III) alkyl complexes

The equilibrium geometries of gold (III) alkyl complexes are optimized by DFT/B3LYP method. On the basis of the optimized structures, the electronic structures and second-order nonlinear optical properties are calculated by using time-dependent density-functional theory (TDDFT) combined with the sum-over-states (SOS) method. The results show that these complexes possess remarkably larger molecular second-order polarizabilities compared with the typical organometallic and organic complexes. The analysis suggests that charge transfer from the z-axis directions plays a key role in the second-order nonlinear optical response. Moreover, different ancillary ligands can substantially adjust the second-order nonlinear optical response. Thus, it can be concluded that these complexes will be hopeful candidates for the second-order nonlinear optical materials from the standpoint of high transparency, relatively large β values and small dispersion behaviors.     

Octa- and tetra-(benzo-15-crown-5)phthalocyanines in surfactant-containing solutions

The behavior of octa-(benzo-15-crown-5)phthalocyanine (H₂cr₈Pc), as well as cobalt octa- and tetra-(benzo-15-crown-5)phthalocyaninates (Cocr₈Pc and Cocr₄Pc), in aqueous solutions containing cationic or anionic surfactants, such as cetyl trimethylammonium bromide (CTAB), sodium carboxymethyl cellulose (Na-CMC), and sodium dodecyl sulfate (SDS), is studied using electronic spectroscopy. The presence of eight benzo-15-crown-5 ether fragments on the periphery of the phthalocyanine ring is shown to facilitate the dissolution of Pc in an aqueous environment. The interactions between CTAB and crown-containing Pc promotes the dissolution of H₂cr₈Pc; Cocr₈Pc; and, to a lesser degree, Cocr₄Pc, which is accompanied by the appearance of molecular aggregates, including heteronuclear cofacial dimers. The presence of a metal in the ring is not the necessary condition of the process. In microscopically heterogeneous medium, such as an aqueous SDS-containing solution, H₂cr₈Pc is present in monomeric form at SDS concentrations close to C _cr and in dimeric form at SDS content below C _cr. Under similar conditions (environment, surfactant), Cocr₄Pc can exist in monomeric form at SDS concentrations much high than C _cr. The effect of the size of cation on the form of the crown-containing Pc in an aqueous solution is illustrated by an example of H₂cr₈Pc. Na-CMC promotes the dissolution of Pc and enables one to produce K⁺/Mcr₈Pc-modified films from aqueous solutions.     

Temperature dependence of optical properties of aluminum(III) <Emphasis Type="Italic">meso</Emphasis>-tetra(benzo-15-crown-5)porphyrinate solution in toluene

Aluminum(III) meso-tetra(benzo-15-crown-5)porphyrinate (AlClTCP) is produced from aluminum(III) chloride and meso-tetra(benzo-15-crown-5)porphyrin (H₂TCP) in boiling pyridine. The structure of the novel compound was determined by electronic absorption spectroscopy, nuclear magnetic resonance, and MALDI TOF mass spectrometry. The color of the AlClTCP solution in toluene was found to depend on temperature, namely, the heated solution is pink, while the cooled one is green. Changes in the electronic absorption spectra and fluorescence spectra of the solution depending on temperature are analyzed. According to the data of dynamic light scattering, gradual cooling of the AlClTCP solution in toluene heated to 120°C results in the formation of nanoparticles with a mean diameter of several hundred nanometers that assume a spherical shape. The self-assembly is assumed to take place via the change from the monodentate coordination of the chloride anion by Al³⁺ cation in AlClTCP molecules to a bridgelike coordination.     

Physicochemical properties of solutions and ultrathin films of triple-decker gadolinium tetra-15-crown-5-phthalocyaninate

The ability of the triple-decker gadolinium complex with tetra-15-crown-5-phthalocyanine Gd₂(R₄Pc)₃, (R = 15-crown-5) (1) to form monolayers and Langmuir-Blodgett films (LBFs) was studied for the first time. The charge characteristics of molecules of a triple-decker phthalocyaninate in monolayer, as well as their orientation and adhesion to the water subphase, were controlled by changing the surface pressure, pH, and subphase composition (aqueous solutions containing triethylenetetramine (TETA) and metal cations). It was shown that the presence of Na⁺ and protonated TETA aminogroups in resulted in an increasing limiting monolayer area and significant decreasing of the monolayer liquid state region. It is proven that the observed effects are caused by the conformational and charge transitions of peripheral crown ethers induced by their interaction with cations. A comparison of the differential reflectance spectra of the complex monolayer on the deionized water surface with UV-Vis absorption spectra of three-layer Gd₂(R₄Pc)₃ LBF and complex solution in chloroform shows that partial complex oxidation and intensive stacking formation occurs already at the stage of monolayer formation on the subphase surface. Electrochemical studies of three-layer LBFs performed at the indium-tin-oxide electrodes (ITO-electrodes) using cyclic voltammetry (CV) showed three reversible redox waves in the potential range −200 to +1100 mV (vs. Ag⁺/AgCl). All registered peaks remain the same position and intensity upon multiple cycling. plasmon resonance (SPR) measurements allow to register three stable redox states of studied LBF upon applying the external potential. Such behavior shows the possibility to use multistep redox transformations of studied complex LBF for developing of stable and reproducible switchable optoelectronic systems.     

Synthesis and studies of mesomorphism of new octa-(benzo-15-crown-5)-substituted phthalocyanines and transition metal phthalocyaninates

Previously unknown octa-(benzo-15crown-5)-substituted phthalocyanine (1) and its metallocomplexes with Ni(II) (2), Co(II) (3), Cu(II) (4), Zn(II) (5), and Cd(II) (6) are synthesized. The possible formation of mesophases of these compounds is predicted and their mesomorphic properties are studied. It is found that compounds 1, 2, and 4 exhibit high-temperature enantiotropic mesomorphism typical of discotic mesogenes, which is well consistent with the predicted results. Free phthalocyanine (1) reveals dimesomorphism according to the DSC and thermomicroscopic data. According to the studies of miscibility of compound 1 with discotic mesogene, 2,3,6,7,10,11-hexa(cyclohexanebenzoyloxy)triphenylene, which exhibits nematic mesomorphism. The second phase transition is identified as the transition to a nematic phase. According to the texture of this mixture, compound 1 was classified with discotic mesogenes that form columnar nematics (N_Col). The first phase transition of 1 from a crystal to the mesophase was identified as columnar (Col). Phthalocyanines of cobalt (3) and copper(4) revealed latent mesomorphism according to the studies of their mixtures with the chiral nematic liquid crystal of cholesterin diphenylate.     

Synthesis,Structure, and Photophysical Properties of New Gallium(III) and Indium(III) 15-Crown-5-Substituted Porphyrinates

Protection of Metals and Physical Chemistry of Surfaces - New indium(III) and gallium(III) meso-tetra(benzo-15-crown-5) porphyrinates are synthesized. The structure of complexes is determined from...     

The effect of aggregate state of octa-(benzo-15-crown-5)-substituted phthalocyanines in aqueous solutions on the structure of self-organized composites of ultrathin ion layers

The method of layer-by-layer (LbL) deposition from aqueous solutions was used to obtain electrostatic self–organized composites consisting of cationic fragments of octa-[(4′-benzo-15-crown-5)oxy]phthalocyaninates of metals (Mcr8Pc)/K⁺ and anionic fragments of sodium polystyrenesulfonate or 4,4′,4″,4?-[cobalt phthalocyaninate-2,(3),9,(10),16,(17),23,(24)-tetrayl-tetrakis(oxy)]-tetrabenzoic acid. The electronic absorption spectra of composite coatings indicate preservation of structures formed in aqueous solutions of Mcr₈Pc: coaxial associates, noncoaxial associates, and high-order aggregates. An increase in the content of noncoaxial associates and the possible presence of suspension particles in the composite are observed.     

Synthesis, structure and fluorescence properties of a highly stable indium(III)-2,5-pyridinedicarboxylate coordination polymer

The hydrothermal reaction of 2,5-pyridinedicarboxylic acid (H₂PDC), diethylene triamine and In(NO₃)₃·4.5H₂O gave rise to a two-dimensional (2D) coordination polymer In(OH)(2,5-PDC). This compound crystallizes in the orthorhombic space group Iba2, with cell parameters, a = 12.656(3) Å, b = 20.114(4) Å, c = 6.2216(1) Å, V = 1583.9(5) Å³ and Z = 8. Its structure contains one-dimensional In–O–In–O– chains, which are further linked by 2,5-PDC ligands into a 2D supramolecular neutral framework. The adjacent 2D layers are parallel with each other and construct a three-dimensional framework via hydrogen bands. At room temperature, the compound exhibits intense photoluminescence. On the basis of the results of TG/DTA analyses, the structure is thermally stable up to 390 °C.     

Formation of surface layers upon evaporation of meso-tetra(benzo-15-crown-5)porphyrin on nanostructured iron surfaces

Morphology and spectral characteristics of the surface structures obtained upon the evaporation of meso-tetra (benzo-15-crown-5)porphyrin on the iron surface are studied with the use of digital optical microscopy, IR Fourier-transform spectroscopy, and x-ray diffraction analysis. During the interaction of porphyrin chloroform solution with nanostructured iron-based metal-oxide nanocomposite template, the process at the original template boundary is shown to initiate the formation of two polymorphous modifications of a porphyrin layer, namely, the aggregated layer and a transparent vitreous layer.     

Synthesis and crystal structure and nonlinear optical properties of polymeric W （Mo）-Cu-S cluster

The polymeric chalcogenide [W2O2S6Cu4（NCMe）4]n （compound 1） was synthesized by the self-assembly reaction of （NHa）2（WOS3） with CuBr in MeCN in the presence of tricyclohexylphosphane （PCy3） under a purified nitrogen atmosphere using standard Schlenk techniques. It gives rise to a novel ID polymeric compound 1 with solvent MeCN coordinated to the copper atom. This situation is unprecedented in the W（Mo）/Cu/S system. The crystals were characterized by elemental analysis, IR and single-crystal X-ray crystallography. The configuration of the polymeric compound can be viewed as a helical chain which is propagated along the crystallographic c axis. The excited state absorption and refraction of compound 1 in CH3CN solution were studied by using the Z-scan technique with laser pulses of 40 ps pulse-width at a wavelength of 532 nm. The polymeric compound possesses an optical self-focusing performance. The positive nonlinear refraction is attributed to population transitions between singlet states. Compound 1 displays a strong excited-state absorption.     

Investigation of photoinduced change of dielectric and electrical properties of indium (III) phthalocyanine and fullerene doped nematic liquid crystal

In this work, we have studied photoinduced dielectric and electrical properties of E63 nematic liquid crystal (E63-LC) materials doped with indium (III) metallo phthalocyanine (In-MPc) and fullerene (C₆₀) in dark and under UV illumination. Doping concentration of In-MPc in E63-LC was chosen to be 5 wt%, whereas a trace amount of C₆₀ was used in investigated samples. Real and imaginary parts of dielectric permittivity were investigated in the frequency range of 100 Hz–10 MHz by using dielectric spectroscopy technique (DST). It was observed that doping agents and UV illumination enhanced the real part of dielectric permittivity at low frequencies, which was thought to originate from photoinduced charge transfer between In-MPc and C₆₀ caused by extra dipole strength in LC medium. In addition to that, critical frequency (f_c) and relaxation time (τ) were obtained and analyzed for all investigated samples. Photoelectrical characteristics of hybrid LC structures were carried out by current–voltage measurements. A major increase in electrical conductivity was observed in In-MPc and C₆₀ doped LC structures under UV irradiation.     

Photorefractive properties of composites based on polyvinyl alcohol,single-wall carbon nanotubes,and fullerene

Composites with photoelectrical, nonlinear optical, and photorefractive properties have been prepared. The composites consist of polyvinyl alcohol, single-wall carbon nanotubes, and fullerene C₆₀. Addition of C₆₀ with a long wavelength boundary near 630 nm resulted in an eight- to tenfold increase in both the quantum efficiency of generation of mobile hole charges and the photorefractive two beam gain coefficient measured at wavelengths exceeding 1000 nm (over an area of optical absorption of nanotubes). This is attributed to electron trapping by acceptor fullerene, which limits the regeneration of photogenerated charges and provides an increase in mobile hole charges.     

Effects of substituents on the third-order nonlinear optical properties of poly(3-alkoxythiophene) derivatives

Poly(3-alkoxythiophenes) (P3AOTs) have been synthesized with octoxyl, dodecaoxyl and 4-nitro-benzyloxyl as sidechains, respectively. The novel poly(3-octoxycthiophen)-co-poly(3-(4-nitro-benzyloxy)-thiophene) (P3OOT-co-P3NBOT) has also been prepared. The absorption spectra of samples indicate that the side groups affect the bandgap of P3AOTs. The nonlinear optical (NLO) properties of P3AOTs were investigated using Z-scan method. The third-order NLO susceptibility (χ⁽³⁾) of the polymers shows a strong dependence on the length of the alkoxyl sidechains and polarity of polymers, which affect the intra- and intermolecular charge transfer. These polymers have potential application in optical limiting device.     

Chain flexibility and nonlinear optical properties of conjugated molecules

The influence of conformational disorder on the nonlinear optical behaviour of push–pull polyenes, is discussed with the help of vibrational spectroscopy. Vibrational molecular hyperpolarizabilities have been evaluated according to the vibrational method.     

New Hybrid Materials Based on Nanostructured Aluminum Oxyhydroxide and Terbium(III) Bis(Tetra-15-Crown-5-Phthalocyaninate)

A new method was developed for preparation of hybrid functional nanostructures through interaction between terbium complex with tetra-15-crown-5-phthalocyanine Tb[(15C₅)₄Pc]₂ and the surface of highly porous nanostructured aluminum oxyhydroxids (NAOs). It was shown that immobilization of phthalocyaninate on an NAO surface may be reversible upon a sorption from the solution in chloroform, and irreversable, when the adsorption occurred on the NAO surface that was chemically modified using methyltrimethoxysilane and annealed at the temperature ranging from 500 to 1100°С (NAOM). Nanostructure and chemical properties of the obtained hybrid nanomaterials were studied with the use of different methods: scanning electron microscopy, XRD, IR and diffuse reflectance spectroscopy. The sensor properties of the obtained Tb[(15C₅)₄Pc]₂//NAO and Tb[(15C₅)₄Pc]₂//NAOM hybrid nanostructures were studied when they interacted with ammonia and iodine vapors. It was shown that the phthalocyaninate complex on the NAO surface was liable to reduction, while the phthalocyaninate complex on the modified NAOM surface was liable to oxidation.     

Dielectric characteristics and nonlinear properties of ZnO–polypyrrole composites

The nonlinear properties and frequency characteristics of ZnO–polypyrrole composites were investigated at 200 Hz–5 MHz frequency interval with different zinc oxide contents. Samples were prepared using hot press method at 130 °C. Results show an optimum point for breakdown voltage at ZnO content of 70%. Breakdown voltage decreases from 590 to 380 V and after that tends to increase from 450 to 740 V due to the absence of polypyrrole at grain boundaries. No matter how breakdown voltage behaves, nonlinear coefficient increases from 4.2 to 9 by increasing ZnO content because of the increase in acceptor-like states at grain boundaries by increasing ZnO content. The electrical parameters such as dielectric constant, dielectric loss and series resistance of samples show a strong dependence on frequency especially below 1 kHz. These parameters fall off by increasing frequency up to 1 kHz, which is related to charge transportation through the Schottky barrier at grain boundaries. The high dielectric constant of samples below 1kHz is related to the Maxwell–Wagner polarization at grain boundaries. The presence of different anomalies at different frequency intervals is related to interfacial polarization because of different structures of grains and intergranular layer with a huge difference in conductivity.     

Complexes of zinc(II) tetra-(15-crown-5)-phthalocyaninate with axially coordinates N-donor ligands as potential components of photosensitive materials of telecommunication range

The methods of electron absorption spectroscopy and ¹H NMR were used to study the processes of interactions between zinc tetra-(15-crown-5)-phthalocyaninate and a number of N-donor ligands, including 1,4-diazabicyclo[2.2.2]octane, 4-dimethylaminopyridine, 3-aminopyridine, imidazole, 2-amino-5-methylpyridine, 2-methyla-4-aminopyridine, 2,3-diaminopyridine, pyrazine. A new effective method for synthesizing zinc tetra-15-crown-5-phthalocyaninate was developed that allowed one to obtain the complex at a yield of greater than 80% under simple conditions in 2 h. The structure of associates was studied in detail using the example of interactions between zinc tetra-15-crown-5-phthalocyaninate and 1,4-diazabicyclo[2.2.2]octane. ¹H NMR studies in a wide temperature range of 213–323 K (−60 to +50°C), as well as quantum-chemical calculations, allowed us to establish the formation of two types of associates of phthalocyanine and 1,4-diazabicyclo[2.2.2]octane with the composition of 1: 1 and 2: 1. Up to a temperature of 253 K, the 1: 1 and 2: 1 associates are in equilibrium with a high rate of interconversion.     

Substituted tetra-2,3-pyrazinoporphyrazinino copper(II) complexes: synthesis and nonlinear optical refractive and absorptive properties

Tetra-substituted tetra-2,3-[5,6-(9,10-phenanthro)pyrazino]porphyrazinino copper(II) complexes (AzaPhc, 5a–d) have been prepared via complexation of mono-substituted 5,6- (9,10-phenanthro)-2,3-dicyanopyrazines with copper(I) chloride. Their nonlinear optical properties have been studied by the Z-scan measurements at 532 nm. We found that their effective nonlinear refractive indices n₂^eff (ranging from −4.6×10⁻¹⁰ to −10.0×10⁻¹⁰ e.s.u.) are about two to four times larger than the octa-substituted phthalocyaninine complex, and their triplet excited-state absorption cross sections σ_ex^τ (ranging from 8.2×10⁻¹⁹ to 9.8×10⁻¹⁹ cm²) are about an order less than the phthalocyanine compound. The one-photon excitation and the heating effect have been applied to interpret our experimental results.