Yu. G. Gorbunova

Orthophosphoric Acid-;N,N-Dimethylformamide System: IR Study

Interactions in the orthophosphoric acid (H3PO4)-;N,N-dimethylformamide (DMF) system are studied by IR Fourier spectroscopy. A mechanism of interaction between the H3PO4 and DMF molecules was proposed on the basis of the results and the earlier reported viscosimetry data for this system.

Crown-substituted phthalocyanines—components of molecular ionoelectronic materials and devices

This review summarizes the synthetic approaches towards oxa-crown-substituted phthalocyanines (CRPc’s) including various metal complexes of s-, p-, d-, and f-elements. The template cyclotetramerization of phthalonitriles and direct metalation pathways for synthesis of target compounds are discussed and compared. It is demonstrated that obtained results have contributed to coordination, supramolecular, and materials chemistry of phthalocyanines in general. An analysis of the results published to date reveals the challenges of these compounds for their use in high-tech applications.

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 E0 = 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.

Synthesis and structure of heteroleptic triple-decker neodymium, europium, holmium, erbium, and ytterbium crown phthalocyaninates

Two series of heteroleptic crown-substituted tris(phthalocyaninate) complexes (Pc)Ln[(15C5)4Pc]Ln(Pc) and [(15C5)4Pc]Ln[(15C5)4Pc]Ln(Pc), where 15C5 is 15-crown-5, (Pc2−) is the phthalocyaninate dianion, Ln = Nd, Eu, Ho, Er, and Yb, were prepared by the reaction of tetra-15-crown-5-phthalocyanine H2[(15C5)4Pc] with the corresponding lanthanide acetylacetonates and lanthanum bis(phthalocyaninate) La(Pc)2, which was used as a phthalocyaninate dianion donor. The composition and structure of the synthesized complexes were confirmed by MALDI TOF mass spectrometry, UV-Vis absorption spectroscopy, and 1H NMR. Complete assignment of the proton resonance signals of the paramagnetic lanthanide complexes was based on analysis of lanthanide-induced shifts.

Orientation-induced redox transformations in Langmuir monolayers of double-decker cerium bis[tetra-(15-crown-5)-phthalocyaninate] and multistability of its Langmuir-Blodgett films

The spectral, electrochemical, and optical properties of Langmuir-Blodgett films (LBFs) and cast films from a solution of new double-decker cerium bis[tetra-(15-crown-5)-phthalocyaninate] (Ce(R4Pc)2) are studied. Based on analysis of compression isotherms and quantum-chemical calculations, schemes of the organization of Ce(R4Pc)2 molecules at different states of its monolayers are proposed. Correlation dependences are determined in order to relate the optical and electrochemical characteristics of monolayers and LBFs of sandwich-type lanthanide phthalocyaninates to the ionic radii of their metal centers. The valent state of Ce ions in a monolayer-forming complex is determined, and a sequence of redox transformations occurring in LBF uppon appliance of a potential is proposed, one of the transformations being associated with the Ce3+/Ce4+ redox transition. Orientation-induced intramolecular electron transfer is revealed in the planar supramolecular system. It is shown that, during the formation of a monolayer from a Ce(R4Pc)2 solution, a tetravalent metal center passes to a trivalent state. Monolayer compression to a high surface pressure reverts the complex to the electronic state typical of the solution. The reversible transformations observed upon the monolayer compression result from intramolecular electron transfer from the 4f-orbital of Ce to the phthalocyanine ring and backwards. The high operation rate and the reversibility of switching between the stable states, which are determined by means of the surface plasmon resonance technique, upon a stepwise change in the electrode potential within the range of 200–850 mV may underlie the development of optoelectronic systems. With a large number of molecules in a stacking aggregate, changes in the distance between the decks of the complex that occur with changes in the oxidation level of the metal center can substantially modulate the sizes of molecular ensembles. A supramolecular device capable of performing mechanical work can be developed based on this effect.

Photoelectric, nonlinear optical, and photorefractive properties of composites based on poly(N-vinylcarbazole) and gallium phthalocyaninate

Poly(N-vinylcarbazole) layers containing tetra-5-crown-5-gallium phthalocyaninate (R4Pc)Ga(OH) are shown to possess photoelectric and photorefractive sensitivity at a wavelength of 1064 nm. This effect is associated with the formation of supramolecular ensembles of (R4Pc)Ga(OH) molecules with electronic optical absorption in the near-IR range and nonlinear optical properties. For the composite containing 5 wt % (R4Pc)Ga(OH) supramolecular ensembles, the dependence of the quantum efficiency of mobile-charge photogeneration on electric field E0 is well fit by the Onsager equation expanded to E03 at a quantum yield of electron-hole pairs of φ0 = 0.9 s with an initial separation radius of r0 = 9.8 A susceptibility χ(3) equal to 1.85 × 10−10 esu is measured via the well-known method of electric-field-induced second-harmonic generation. Two-beam-coupling gain coefficient Γ is found to be 80 cm−1 at E0 = 120 V/μm.

Preparation of MF-4SC composite membranes with the anisotropic distribution of polyaniline and ion-transport asymmetry

A method of preparing MF-4SK membranes with the anisotropic distribution of aniline over the thickness is developed. The processes of aniline polymerization in the matrix of the MF-4SC sulfocationite membrane are investigated via electronic-absorption and IR spectroscopy. The processes of ion transport in the obtained composite membranes are studied via impedance spectroscopy, voltammetry, and potentiometry.

Erbium complexes with tetra-15-crown-5-phthalocyanine: Synthesis and spectroscopic study

Erbium mono-, bis-, and tris(phthalocyaninates) with tetra-15-crown-5-phthalocyanine (H2R4Pc) were synthesized and studied by spectroscopic methods. The complexes were obtained by reacting H2R4Pc with erbium salts in high-boiling solvents. To compare the efficiency of two approaches to the synthesis of double-decker lanthanide phthalocyaninates, bis(phthalocyaninate) [Er(R4Pc)2] was also obtained by a template procedure from dicyanobenzo-15-crown-5. A combination of physicochemical methods (UV and IR spectroscopy, MALDI-TOF mass spectrometry, 1H NMR) was used for identifying the compounds and proving their individuality and structure. The photoluminescence method demonstrated that solutions of erbium bis- and tris(phthalocyaninates) in CHCl3 are nonfluorescent in the visible range of light whereas solutions of mono(phthalocyaninate) in CHCl3 and DMSO exhibit fluorescence with maxima at 707 and 695 nm, respectively. The oxidation of erbium mono(phthalocyaninate) leads to fluorescence quenching.

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.

Nonlinear Optical Properties of Systems Based on Ruthenium(II) Tetra-15-crown-5-phthalocyaninate

The third-order nonlinear optical properties of the ruthenium (II) complex with tetra-15-crown-5-phthalocyanine and axially coordinated triethylenediamine molecules (R4Pc)Ru(TED)2 were analyzed by means of the z-scanning technique. A solution of (R4Pc)Ru(TED)2 in tetrachloroethane was exposed to nanosecond laser pulses at a wavelength of 1064 nm. It was found that the third-order molecular polarizability of the Ru(II) complex is 4.5 × 10−32 cm4/C (esu). The polarizability per molecule increases by a factor of 3.6 when the single molecule occurs in a supramolecular assembly of (R4Pc)Ru(TED)2 complexes. The photoelectric and photorefractive properties at 1064 nm of polymer composites, determined by the supramolecular assemblies that exhibits optical absorption and photoelectric sensitivity in the near IR region, are reported.