The interaction of tetraphenylporphyrin with sodium dodecyl sulfate was explored using spectrophotometry and differential scanning calorimetry. The effect of porphyrin on the behavior of the sodium dodecyl sulfate solution in the pre-and postmicellar regions of the surfactant concentration was investigated. It was shown that sodium dodecyl sulfate promotes porphyrin monomerization, and tetraphenylporphyrin pre-organizes sodium dodecyl sulfate micelles.

The prасtiсаl useful prоperties оf sulfо derivаtives оf pоrphyrins depend signifiсаntly оn pH. Fоr exаmple, саnсer сells hаve а mоre асidiс envirоnment (pH = 5.5) соmpаred tо nоrmаl сells (pH = 7.2). The effeсt оf pH (5.5 ≤ pH ≤ 6.5 аnd 7.4) оn the соmplexing аbility tоwаrds BSА аnd the phоtосаtаlytiс асtivity оf sulfо-substituted pоrphyrins соntаining а hydrоphоbiс peripherаl substituent (а residue оf benzоthiаzоle, benzimidаzоle аnd benzоxаzоle) wаs studied.Ассоrding tо аbsоrptiоn аnd fluоresсenсe speсtrоsсоpy, it wаs fоund thаt аt pH = 7.4, pоrphyrins in mоnоmeriс fоrm bind tо prоtein. The lосаlizаtiоn оf pоrphyrins inside the prоtein glоbule wаs prоven by IR speсtrоsсоpy, thermосhemiсаl аnаlysis, stаtiоnаry аnd time-resоlved fluоrimetry. It wаs fоund thаt the соmplexаtiоn оf pоrphyrins with BSА leаds tо аn inсreаse in the prоpоrtiоn оf disоrdered struсtures аnd β-sheets аnd а deсreаse in the thermаl resistаnсe оf prоtein. Phоtоirrаdiаtiоn оf соmplexes оf BSА with pоrphyrins led tо оxidаtiоn оf prоtein struсtures.In the rаnge оf 5.5 ≤ pH ≤ 6.5 pоrphyrins exist in the fоrm оf H-self-аssосiаtes thаt аre nоt destrоyed when interасting with BSА; pоrphyrins dо nоt саuse сhаnges in the seсоndаry struсture оf the prоtein, but inсreаse its thermаl resistаnсe by 10°С. Аnаlysis оf phоtосаtаlytiс асtivity shоwed thаt pоrphyrin lоses its аbility tо phоtо-оxidize prоteins in weаkly асidiс envirоnments.

Polystyrene/halloysite composite film materials were prepared by the mechanical dispersion method. Differential scanning calorimetry and thermogravimetric analysis were used to examine thermal destruction and relaxation transitions in the prepared composites. It was established that modification of polystyrene with halloysite raised the glass-transition temperature. The characteristic thermal destruction temperatures of the composite were found to exceed those of the unmodified polymer. The kinetic parameters of the thermal decomposition were determined using the Freeman–Carroll method.

The interaction of cobalt(II) tetrasulfophthalocyanine (CoPc) with the ORF8 accessory protein of SARS-CoV-2 was studied by spectroscopy and calorimetry. The protein was found to shift the aggregation equilibrium in cobalt tetrasulfophthalocyanine solutions towards dimerization. Most probably, the CoPc dimer binds to ORF8 on the greater β-sheet side, thus causing fluorescence quenching. The protein affinity constant to CoPc dimer is 1.5 × 10 5 . Differential scanning calorimetry data indicate that ORF8 undergoes thermally induced denaturation in the temperature range of 38–67°C. Melting of ORF8 includes two stages, which partly overlap. The complex formation of ORF8 with CoPc leads to thermal stabilization of the protein, thus preventing the second stage of protein unfolding. Denaturation of the complex proceeds between 40 and 77°C as two temperature-separated stages. According to gel electrophoresis and immunoblotting data, visible light photoirradiation of the ORF8 complex with CoPc does not induce photooxidation of the protein. It was shown that water-soluble cobalt sulfo-substituted phthalocyanine can be considered as a potential drug inhibiting the ORF8 accessory protein.

Porphyrins, owing to their unique physicochemical properties, hold great potential as candidates for the synthesis of new materials and active pharmaceutical drugs. The introduction of functional groups into porphyrin structures enables the creation of novel compounds with finely tuned structural and optical properties, as well as complex-forming abilities. In this study, spectral and thermochemical investigations were conducted to explore the complex formation of 5-[4′-( N -methyl-1″,3″-benzoimidazol-2″-yl)phenyl]-10,15,20-tris-( N -methyl-3′-pyridyl)porphyrin triiodide with synthetic (poly[d(GC)2], poly[d(AT)2]) and natural (ssDNA, ctDNA) nucleic acids. It was observed that the porphyrin forms complexes with poly[d(AT)2] and ssDNA, localized within the major groove of the biopolymer. Additionally, the porphyrin forms multiple intercalation complexes with varying geometries when interacting with poly[d(GC)2] and ctDNA. These findings demonstrate a new potential for enhancing the selective binding of ligands with nucleic acids (NA). Moreover, the study highlights the methodological aspect that establishing the type of formed complexes based on ligands’ electronic absorption spectra, known as “fingerprints,“ may lead to incorrect conclusions.

The complex formation of monoheteryl-substituted tricationic porphyrins with representative polynucleotides (poly[d(GC)2] and poly[d(AT)2]) was studied. It has been spectrally established that the studied porphyrins form intercalation complexes of different geometry with poly[d(GC)2]: 1) intercalation between the nitrogenous bases of the porphyrin macroring; 2) intercalation between the nitrogenous bases of the monoheteryl substituent. The studied porphyrins form complexes with the poly[d(AT)2] groove. The DSC method was used to analyse the temperature dependences of the specific heat capacities of solutions of the initial reagents and complexes of porphyrins with poly[d(GC)2] and poly[d(AT)2]; it was found that the proportion of structural changes in the analysed solution associated with intercalation significantly exceeds the similar value during the formation of the complex in the groove of the nucleic acid. The results obtained demonstrate a new potential opportunity to increase the selectivity of binding of ligands to nucleic acids.

We studied the influence of the position of the N-methyl group in tetra-(N-methylpyridyl)porphyrin on the features of its interaction with oligonucleotides using experimental physicochemical methods. Spectral methods detecting changes in the photophysical properties of chromophore ligands made it possible to prove the mechanism of binding to poly[d(AT)2] and poly[d(GC)2]. The thermochemical method made it possible to evaluate the structural consequences of ligation of oligonucleotides, and in the case of tetra-(3-N-methyl-pyridyl)porphyrin, to clarify the mechanism of binding to oligonucleotides. The combination of spectral and thermochemical analysis is useful for elucidating the structure of ligand complexes with synthetic and natural DNA.

Mechanical dispersion was used to modify ethyl cellulose with the particles of bentonite clay. The prepared ethyl cellulose/bentonite composite film materials were characterized by optical microscopy and X‑ray diffraction. The thermal behaviors of both the films and the initial polymer powder were studied by using differential scanning calorimetry. It was found that the introduction of bentonite reduced the characteristic temperatures of glass transition and melting of the polymer material.

A theoretical and experimental study of the interaction of the SARS-CoV-2 ORF10 protein with sulfosubstituted cobalt(II) and copper(II) phthalocyanines was carried out. The structures of the most probable complexes of metal phthalocyanines with the ORF10 protein were obtained by molecular docking methods. Cobalt(II) tetrasulfophthal ocyanine binds to the protein in the monomeric state, while the interaction ofORF1 0 with copper(II) tetrasulfophthalocyanine causes aggregation of the formed protein complexes, which was shown by the UV-Vis spectroscopy. Thermal denaturation of the ORF10 protein and its complexes with metal phthalocyanines was studied by differential scanning calorimetry. A joint analysis of the spectral and thermochemical data made it possible to propose a description of the mechanism of thermal denaturation ofthe ORF10 protein.

Albumin is a globular protein with a number of functions of vital importance. Its aggregation can cause serious problems and cause hypoalbuminemia. Albumin complex formation with endogenous and exogenous porphyrins can lead to aggregation. This work is a study of the localization effect of a number of endogenous porphyrins, such as protoporphyrin, hematoporphyrin, deuteroporphyrin and their metal complexes in an albumin globule on the albumin state in solutions and resistance of protein complexes to thermally induced denaturation. The structure of the obtained complexes was determined by the IR and fluorescence spectroscopy methods in combination with molecular docking. The results obtained show that nature porphyrins form hydrogen bonds with various sections of the albumin polypeptide chain and cause changes in the protein secondary structure associated with the transformation of alpha-helices into beta-folds and subsequent protein aggregation. The DSC studies revealed that complex formation with porphyrins lowered the thermal effect of protein denaturation by 50-67%. The dependence of the structure of the complexes on the denaturation thermal effect was analyzed. It was established that the changes in the protein denaturation thermal effect could be used to determine porphyrin localization in the protein globule and protein ability to form aggregates, following complex formation. (C) 2021 Published by Elsevier B.V.

Polyamide 12 is a popular material for manufacturing 3D printing powders, but the existing technologies require harsh processing conditions. This study suggests a new route to obtain powders via the thermally-induced phase separation of polyamide 12 – benzyl alcohol mixtures, which proceeds at ambient pressure without using highly toxic substances. The approach is based on the experimental phase diagram of this system constructed for the first time using an original optical method. The analysis of this diagram allows us to choose the concentration–temperature range suitable for the formation of polymer suspension. It appears that the mean size and dispersity of powders are more sensitive to the rate of cooling than to the composition of the initial polymer–solvent mixture. The parameters of the obtained powder (melting/crystallization temperature, degree of crystallinity, bulk density, and particle size distribution) are close to those of several trademarks, thus making our approach promising for practical realization.

Results are presented from a physicochemical study of magnetite magnetic fluid of synthesized with addition of graphene. It is shown that adding graphene during the synthesis of the dispersed phase affects the specific surface of the magnetic phase, the thermal stability, the viscosity, and the heat capacity of the magnetic fluid.

The multistage purposeful synthesis of 5,15-bis(4′-l-N-tyrosinylamidophenyl)-10,20-bis(N-methylpyridin-3′-yl)porphine diiodide was carried out, and the optimum synthesis conditions were determined. 5,15-Bis(4′-nitrophenyl)-10,20-bis(pyridin-3′-yl)porphine served as the starting porphyrin. The structure, individual character, and purity of the target compound were proved by electron spectroscopy, 1H NMR spectroscopy, mass spectrometry (MALDI TOF), and TLC. Specific features of the interaction of the synthesized porphyrin with S-protein of SARS-CoV-2 were studied using spectral and thermochemical methods, including conditions of photoirradiation. The photoirradiation of the synthesized porphyrin in a complex with the SARS-CoV-2 S-protein can result in the partial oxidation of amino acid residues of the protein and distort its primary and secondary structures. The photoirradiation of the S-protein complex with the porphyrin decreases its thermal resistance to melting by 15 °C compared to the free S-protein and causes porphyrin release.

Chitosan is a naturally occurring polysaccharide derived from chitin with a wide range of uses. Phthalocyanines are macroheterocyclic compounds that have a number of useful properties such as coloring and catalytic and antioxidant activity. Phthalocyanines are able to immobilize on chitosan, forming complexes with new useful properties. In this work, we evaluated the ability of phthalocyanines to increase the thermal stability of chitosan. Chitosan (CS) forms complexes with copper(II)-(CuPc) and cobalt(II)-(CoPc) tetrasulphophthalocyanines. The processes of destruction of chitosan (CS) and its complexes with sulphophthalocyanines CuPc and CoPc in oxidizing and inert atmospheres have been studied. It was established that, regardless of the atmosphere composition, the first chemical reactions taking place in the studied systems are elimination reactions. The latter ones in the case of chitosan and complex CS-CuPc lead to the formation of spatially crosslinked polymer structures, and it causes the release of CuPc from the polymer complex. It was found that in the case of CS-CoPc elimination reactions did not lead to the formation of crosslinked polymer structures but caused the destruction of the pyranose rings with a partial release of CoPc. Metallophthalocyanines showed antioxidant properties in the composition of complexes with chitosan, increasing the temperature of the beginning of glycosidic bond cleavage reaction by 30–35 °C in comparison with the similar characteristics for chitosan.

Highlights:Polymer complexes of chitosan with copper and cobalt phthalocyanines were obtainedDecomposition products of chitosan and polymer complexes with metal phthalocyanines were determinedPyrolysis of chitosan and its polymer complexes with metallosulphophthalocyanines leads to the formation of carbonizatesThe introduction of copper phthalocyanine into the composition of the polymer complex with chitosan leads to an increase in the content of aliphatic structures in carbonizates, and cobalt phthalocyanine in aromatic compounds

For the first time, a comprehensive analysis has been done of the effect of synthesis conditions on the properties of an ionic liquid bound in the 1-butyl-3-methylimidazolium acetate - Na-bentonite ionogel. The ionogels were obtained by mechanical abrasion and through adsorption of 1-butyl-3-methylimidazolium acetate on Nabentonite from acetone and a water-acetone solution. The prepared materials were characterized by X-ray diffraction, thermogravimetric and differential thermal analysis, FT-IR spectroscopy and dielectric spectroscopy. The obtained data made it possible to characterize the properties of the ionogel including the ionic liquid in different states - sterically stabilized by bentonite particles and being in the state of confinement in the nanopores of layered aluminosilicates. It has been found that introduction of an ionic liquid into the interlayer space of clay changes the dimensions of the basal spacing between the aluminosilicate plates. This is due to the packing density of the ionic liquid molecules between the clay layers. Confinement in clays also affects a number of other properties of ionic liquids. It has been shown that confinement causes changes in the IR-spectra of the ionic liquid, increases its thermal stability by 100 degrees C, and shifts the dielectric loss tangent on the dielectric relaxation spectrum towards lower frequencies. (C) 2020 Elsevier B.V. All rights reserved.

The enthalpies of dissolution, Delta H-sol(m)infinity, and solvation, Delta H-solv(m)infinity, ether oligomers CH3O(CH2CH2O)(n)CH3 (n = 1-4) in ethyl acetate, pyridine, N,N-dimethylformamide, and acetonitrile have been determined from calorimetric measurements at 298.15 K. The values of group contributions of repeated ether units and monoether fragment have been compared on the basis of the additive method. The contributions of ether group to Delta H-solv(m)infinity for oligomeric and monomeric molecules coincide within their uncertainties for solutions in highly polar solvents, in contrast to non-polar, moderately polar, and H-bonding solvents. The dependence of ether group contributions to Delta H-solv(m)infinity on the electron pair acceptance index of solvents E-T(N) has been considered.