The optical absorption, fluorescence, and phosphorescence spectra of RNAs and oligonucleotides of different origin, as well as their mixtures with human albumin are investigated. It is confirmed that the energy structures of DNA, RNA, and complex protein macromolecules are determined mainly by the individual properties of their p-electron systems. The positions of the RNA excited singlet and triplet energy levels obtained by authors' previous work are determined more precisely. It is shown that mainly adenine bases are traps for mobile triplet excitons in RNA (contrary to DNA, in which AT complexes are the triplet traps). The spectral manifestation of the RNA=oligonucleotides-albumin interaction is studied. It turns out that namely the phosphorescence spectra of these compounds due to their sharp structure at 4.2 K are the most suitable for the study of the RNA-albumin interaction. The phosphorescence spectra of albumin-2 0 5 0 A 3 solvents manifest the penetrative binding of 2 0 5 0 A 3 to an albumin macromolecule. The obtained data show that at least a weak non-penetrative binding of RNA to human albumin can exist.

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The effects of multiwalled carbon nanotubes (NTs) on low-temperature phase transformations in 5CB were studied by means of differential scanning calorimetry (DSC), low-temperature photoluminescence and measurements of electrical conductivity. The concentration of NTs was varied within 0-1% wt. The experimental data, obtained for pure 5CB by DSC and measurements of photoluminescence in the heating mode, evidenced the presence of two crystallization processes at T≈229 K and T≈262 K, which correspond toC phase transformations. Increase of temperature T from 10 K до 229 K provoked the red shift of photoluminescence spectral band that was explained by flattening of 5CB molecule conformation. Moreover, the photoluminescence data allow to conclude that crystallisation at T≈229 K results in conformation transition to non-planar 5CB structure characteristic to ideal crystal. The non-planar conformations were dominating in nematic phase, i.e., at T>297 K. Electrical conductivity data for NTs-5CB composites revealed supplementary anomaly inside the stable crystalline phase C 2 , identified earlier in the temperature range 229 K-296.8 K. It can reflect the influence of phase transformation of 5CB in interfacial layers on the transport of charge carriers between NTs.

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The structure and photoluminescent properties of natural montmorillonite (MMT) aluminosilicates from three mineral deposits that were modified by cations of sodium or the surfactant cetyltrimethylammonium bromide (CTAB) have been investigated. X-ray fluorescence analysis showed significant differences in the concentrations of the inorganic dopants in these materials. An x-ray diffraction analysis established that incorporation of the CTA + long-chain cations into the MMTs expands remarkably the mineral interplanar distances, the values of which are close to each other for all organoclay samples under study and equal to 1.8-2.0 nm. The photoluminescent properties of the Na-form of the MMTs are shown to depend on the amount of introduced dopant capable of either enhancing or quenching the emission. Deposition of CTAB on the mineral surface influences the luminescence pattern, the spectral contour and wavelength range being practically the same for all modified samples. The emission may intensify or weaken because of such surface modification.Introduction. Natural layered clay minerals (CM) with the 2:1 structure type are highly disperse and have a large specific surface area. They are known to be selective sorbents and effective ion-exchangers [1, 2], active catalysts for various processes (isomerization, polymerization, addition, etc.[3]), fillers of organic media, plastifiers of polymeric materials [4-8], etc. The particles of these CM are stratified in a liquid medium. Their thickness is of the order of nanometers; the width/length, 25-1000 nm. Their surface is organophobic in the unaltered state. Owing to the presence in the CM interplanar space of metal cations that are susceptible to ion exchange, it is rather easy to convert the surface into an organophilic one via exchange of the inorganic cations by organic ones using ion exchange. As a result, the affinity of the resulting organoclays for an organic medium [polymers, liquid crystals (LC), aromatic compounds, etc.] increases sharply. Heterocomposites with a homogeneous structure (coagulation network) consisting of nanoparticles of the organoclay and the organic matrix are formed at a certain concentration of them. For example, LC filled with CM particles modified by various surfactants (SA) exhibit a variety of electro-optical properties [9][10][11].The starting CM in the present work was montmorillonite (MMT) from three deposits: Pyzhev (Ukraine), Cherkassy (Ukraine), and Askan (Georgia). MMT is a layered natural aluminosilicate of the 2:1 structure type that consists of two layers of SiO 2 tetrahedra between which a layer of Al 2 O 3 octahedra is located. These samples differ in the impurity profile, dispersion, cation-exchange capacity (CEC), and magnitude of surface charge. This should affect their properties (in particular, optical ones). We studied two series of these CM. One of them was the Na-form of the samples; the other, MMT modified with an organic molecule. The organic surface modifier was cetyltrimethylammonium bromide (CTAB) because this SA...