A. V. Kazak

Influence of meso-substituted tetraphenylporphyrin derivatives structure on their supramolecular organization in floating layers and Langmuir-Blodgett films.

To study the influence of structure peculiarities of porphyrin derivatives on their supramolecular organization in thin films, 15 new meso-substituted tetraphenylporphyrin derivatives and their metal complexes with substituents (-OC(4)H(9) or -OC(16)H(33)) in para or ortho positions were studied. The films of the studied compounds were obtained by the Langmuir-Schaefer method. The behavior of porphyrin derivatives at the water-air interface was analyzed, and the conformity of the influence of molecular structure on supramolecular organization in floating layers and Langmuir-Blodgett films was defined. The absorption of these films over a wide spectral range was analyzed. The supramolecular organization of meso-substituted tetraphenylporphyrin derivatives was modeled and specified with the help of X-ray diffraction analysis. It was determined that the formation of monomolecular layers is typical for the compounds with short lateral substituents or without substituents. Tetraphenylporphyrins with extensive substituents can form a monolayer only when zinc is included in the molecular structure.

Influence of molecular structure peculiarities of phthalocyanine derivatives on their supramolecular organization and properties in the bulk and thin films

In order to study the influence of molecular structure peculiarities on supramolecular organization and properties in the bulk and thin films of discotic mesogens six new mix-substituted phthalocyanine derivatives with 3,6-dioctyloxyphthalonitrile and 3,4,5,6-tetrachlorophthalonitrile fragments were synthesized. Temperatures of phase transitions, types of mesophase and their dependence on molecule structure, chemical nature, position and ratio of different substituents as well as presence of holmium in the metal complexes were analyzed. The behavior of the studied molecules on the boundary between water and air was investigated and the peculiarity of supramolecular organization in floating layers as well as in thin films was determined. Quenching of luminescence in solutions of the studied compounds in the presence of fullerene C60 was determined, thus giving prospects for application of these compounds as sensors for fullerene microquantities.

Structure and physicochemical properties of thin film photosemiconductor cells based on porphine derivatives

Photosemiconductor thin films based on two organic porphine derivatives have been investigated. These compounds have different pendent groups; the film morphology, along with the specific fabrication technique, is determined to a great extent by these groups. The films have been fabricated by vacuum sputtering and using the Langmuir−Schaefer method. According to the atomic force microscopy (AFM) data, the Langmuir−Schaefer films are more homogeneous than the sputtered ones. It is shown that the sputtered films based on substituted porphine have a looser stacking than the initial analog. A spectroscopy study revealed a bathochromic shift of the Soret band in the Langmuir−Schaefer films–sputtered films series. This shift is explained by the increase in the concentration and size of molecular aggregates in sputtered films. It is shown that a polycrystalline C60 fullerene film deposited onto an amorphous substituted porphine layer improves the photoelectric characteristics of the latter. Both the time stability of the photodiode structure and its ampere‒watt sensitivity increase (by a factor of 10 in the transition regime). The steady-state current does not change. The effect of polarity reversal of the photovoltaic signal is observed in a planar С60‒substituted metalloporphine heterostructure, which is similar to the pyroelectric effect. The polarity reversal can be explained by the contribution of the trap charge and discharge current at the interface between the amorphous photosemiconductor and crystalline photosemiconductor to the resulting photoelectric current.

Electronic properties of A2B6 quantum dots incorporated into Langmuir–Blodgett films

An experimental and theoretical study is performed for features of the electronic spectrum of CdSe/CdS/ZnS quantum dots incorporated into Langmuir–Blodgett films. Analysis of the investigated samples assesses the state of the first three levels of the electron spectrum for a quantum object. Good qualitative and quantitative agreement is achieved between the experimental results and theoretical estimates. It is shown that the mechanism of the observed field emission current through a quantum dot is described satisfactorily by the Morgulis–Stratton theory under the considered experimental conditions.

Complex approach to the tribotechnical processing of elements for automobile and tractor engines

It has been shown that the addition of a geotribomodifier to engine oil and the processing of rubbing surfaces by metal-cladding agent substantially reduce the mechanical loss (up to 45%) and the heat generation in the contact zone (by 38%) and increases the load-carrying ability (by 61%). The optimal concentration of the friction geotribomodifier additive in oil has been established.

Modeling of interaction of chiral mesogen with carbon nanotube

The possibility of supramolecular organization modeling of a cholesteric liquid crystalline (ChLC) matrix was shown by molecular dynamics simulation using the all-atom model. The supramolecular organization of ChLC mesogen and ChLC - a single walled carbon nanotube composite was estimated and 3D-model of a cholesteric phase of the studied compound was obtained. The effect of a carbon nanotube on the order parameter of ChLC molecules in the cholesteric phase was determined.

Optical properties of Langmuir-Blodgett films of tetraphenylporphin derivatives and mix-substituted phthalocyanine derivatives

The optical properties of Langmuir-Blodgett films of a number of tetraphenylporphin derivatives and heterosubstituted phthalocyanine derivatives with 3,6-dioctyloxyphthalonitrile and 3,4,5,6-tetrachlorophthalonitrile fragments were investigated. The comparative analysis of absorption spectra of the obtained films was carried out. The dependence of optical properties of Langmuir-Blodgett films on the molecular structure of these compounds was established.

Supramolecular organization of meso-substituted derivatives of tetraphenylporphine in thin films

Films of meso-substituted derivatives of tetraphenylporphine substituted in the paraor ortho-positions of the phenyl rings with alkoxy groups (-OC4H9 or -OC16H33) and films of their metal complexes are prepared using the Langmuir-Schaefer (LS) method. The effect of the molecular structure on the supramolecular organization of thin films is determined. The films are obtained by transferring layers of the compounds from the surface of the water onto silicon substrates using the Langmuir-Schaefer technique. The structures of the one-component LS films of the investigated compounds are studied by the small-angle X-ray scattering method, and also the lattice periodicities are calculated. The supramolecular organization of the meso-substituted tetraphenylporphine derivatives is modeled and refined by means of the X-ray diffraction method. When Ni or Cu serve as chelating metal, it is found that the macrocycle-macrocycle interaction is so large that it leads to violation of the molecular linearity, i.e., the lateral substituents are folded toward the macrocycle, reducing the area occupied by the structural units.

Influence of Hexacatenar Structure on Supramolecular Organization in CT-Complexes With TNF and (−)-TAPA

Numerical experiments to obtain theoretical data on the charge transfer complex structure, formed by the substituted benzylamine derivatives (hexacatenars) and electron acceptors—TNF or (−)-TAPA, have been performed. It is shown that the configuration and extent of the central fragment of the hexacatenar molecules influence the supramolecular organization in the modeling CT-complexes.

Influence of Meso-Substituted Porphyrins Molecular Structure on Their Self-Organization in Floating Layers

The influence of molecular structure peculiarities on the supramolecular organization in the bulk and thin layers was studied by the example of two new meso-substituted ligands of tetraphenylporphyrin with substitution in alkoxygroups (-OC4H9) in para- or ortho-positions of phenyl rings. It is established that meso-alkyloxysubstituted tetraphenylporphyrin with substituents (-OC4H9) in the ortho-position (compound I) shows thermotropic monotropic mesomorphism, whereas the substitution in para-position (compound II) leads to the mesophase disappearance. The influence of substituent position on supramolecular organization of meso-substituted porphyrins in thin films was shown.