The rheological behavior of new colloidal systems based on imide derivatives of cymantrene and their organic analogs has been studied for the first time. Rheological fluids based on nano- and microsized particles in polar and non-polar media with different viscosities have been obtained. The influence of irradiation, temperature, and electric field changes on the mechanical properties of fluids has been studied using macrorheology and microrheology methods. Irradiation or heating of systems led to both the destruction of intermolecular bonds and the formation of large aggregates depending on the nature of the solvent. The system based on cymantrenyl phthalimide with a COOH group exhibited an inverse electrorheological effect due to the electrorotation of particles in the medium. Nanofluids based on manganese nanoparticles suspended in toluene and isopropanol have also been obtained. However, exposure to light led to the destruction of aggregates and a sharp increase in viscosity.

To date, donor–acceptor compounds became widely used for various applications, but in many cases fine-tuning of electronic, optical, and electrochemical properties is required. For this purpose, unsymmetrical diimides 4a–c containing one cymantrenyl fragment were obtained in the work using a one-pot competitive imidization. The study of photochemical behavior by IR, NMR, UV–Visible spectroscopy and cyclic voltammetry showed that during photolysis, chelates 5a–c with the Mn–O bond of the nearest imide fragment formed. It was found that thermo-induced ligand exchange occurred in the presence of external ligands, the rate of which depended on the nature of the organic substituent at 2N. For tri- and dicarbonyl complexes, this organic fragment acted as an electron donor. It was shown that the optical and electrochemical properties of asymmetric diimides can be varied both by ligand exchange and by changing the substituent at the second nitrogen of the diimide fragment. Also, the HOMO–LUMO energy gap for chelates 5a–c (1.22–1.30 eV) decreased by 2 times compared to 4a–c (0.56–0.7 eV). Thus, the D–A1–A2 architecture with variable properties due to photo- and thermo-induced ligand exchange is realized.

The photochemical behavior of substituted phthalimides with carboxylate groups associated with the cymantrenyl fragment is studied by infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, UV-visible spectroscopy, and cyclic voltammetry (CV). During the formation of hemilabile dicarbonyl chelate complexes, a sharp change in the electronic, electrochemical, and optical properties of compounds is observed. According to the dynamic light scattering (DLS) method, further irradiation of solutions of these complexes leads to the formation of previously undescribed stable nanoparticles in liquid media containing manganese in two degrees of oxidation Mn2+/Mn+ and a phthalimide fragment associated with a Cp-ring coordinated or uncoordinated with manganese(I).

Novel cymantrene derivatives containing dithiolane and oxathiolane five-membered cycles were prepared. Their spectral, optical, and redox properties were investigated by NMR, IR, UV-vis spectroscopy, and CV. Under the conditions of irradiation and subsequent dark reaction, the effect of ligand exchange on physicochemical properties was studied. Photolysis of tricarbonyl complexes leads to the formation of rare, stable four-membered chelate complexes with Mn & horbar;S bond, one of which has been successfully isolated and characterized by X-ray. However, in the presence of a competitive external ligand (L), the Mn & horbar;S bond dissociated, followed by the formation of new dicarbonyl complexes with the Mn & horbar;L bond, that shows the hemilabile nature of the Mn & horbar;S bond in chelate complexes.

In this study, we evaluated the effect of dissolved organic matter on the sorption of ciprofloxacin by magnetite silica-based nanoparticles (NPs). For this purpose, magnetite nanoparticles modified with organosilanes (tetraethox-ysilane and 3-aminopropyltriethoxysilane, MTA) were used as a model of colloidal particles and a sorbent. Analysis of the absorption spectra found that there was no interaction between antibiotic ciprofloxacin (CIP) and humic substances (HS, sodium salt of humic acids) in aquatic system at pH varied from 6 to 8. But, the behavior of CIP and HS changes dramatically upon addition of silica-coated magnetite nanoparticles. The introduction of the MTA NPs into a bicomponent system of CIP incubated with HS lead to more than twice increased CIP sorption. Results of electrokinetic measurements in terms of zeta-potentials propose the interaction mechanism into CIP-HS-NPs system. In the three-component system, the surface of MTA is completely overcharged from negative to positive, and importantly this effect is pH-dependent. The MTA zeta-potential changes from − 15 (pH 6) and − 30 mV (pH 8) to + 10 (pH 6) and + 2 (pH 8), respectively. The study provides novel scientific information as nanoparticles are increasingly produced and studied for various environmental applications, including sorption of new emerging eco-toxicants (pharmaceuticals) but the assessment of dissolved organic matter contained even in trace concentrations should not be ignored.

Photo- and electrochemical properties of a novel cymantrenyl-containing (CpMn(CO)(3)) phthalimide were studied by cyclic voltammetry, FTIR, H-1 NMR, UV-vis, fluorescence spectral methods. It was found that upon irradiation of the initial tricarbonyl complex, one CO ligand is released to form a colored dicarbonyl chelate, which in the presence of CO enters the reverse thermal reaction to give the initial tricarbonyl complex. In the presence of some other external ligands, the chelate cycle is disclosed and dicarbonyl complex with external ligand is formed demonstrating hemilabile properties of the chelate studied. It was found that the introduction of a cymantrenyl group in a phthalimide molecule, which usually exhibits electron acceptor properties, has a significant effect on the characteristics of the absorption and emission spectra, electrochemical properties. This type compounds can be a basis for the creation of photo- and electroactive materials and exciplex-forming materials

— The results of investigation of the optical and electrochemical properties of substituted phthalimides linked to a cymantrenyl moiety by IR and NMR spectroscopy, UV-Vis spectroscopy, and cyclic voltammetry and also by DFT calculations are presented. It was shown that the optical, donor-acceptor, and redox properties of the organometallic phthalimides are affected by substituents in position 1 of the side chain of the cymantrene Cp and in position 4 of the phthalimide benzene ring. The reactions of dicarbonyl chelates with external ligands in the dark attest to hemilability of the Mn–O=C(imide) bond.

A high-temperature one-step synthesis resulted in two new polymers PI-I and PI-II (polyimides), which have functional groups as SO3H and SO3Na in their chain. Their molecular-mass molecular characterization revealed that PIs are polydisperse systems, and show thermal stability up to 400°C. The dynamic characteristics of polyimide particles in polar and nonpolar media were studied. The particle size of PI-I is significantly affected by the polarity of the medium. Due to intermolecular interactions associated with the free proton, the average particles diameters in dimethylformamide (DMF) was 10 μm, while in polymethylsiloxane (PMS-5) it was 1.4 μm. The size particles of PI-II in different media were 246 and 606 nm. Viscoelastic and mechanical properties of polymer systems were studied using microrheology and classical rheology. Hysteresis loss coefficients (κ) at various temperatures (T) were relatively small and stable for PI-I at T < 60°C with insignificant changes at increasing frequency. PI-II coefficient changes markedly but smoothly as a function of ω (angular frequency) at T < 60°C. With increasing temperature, the values of κ are almost independent of ω, taking quite large values compared to the corresponding values for the PI-I. It was determined that the temperature increases the interaction between the particles of the dispersed phase in the electric field. And the decrease in the viscosity of the suspension is due to a decrease in the viscosity of the medium. The electrorheological effect is most pronounced for the PI-I suspension.

Представлены результаты исследования оптических и электрохимических свойств замещенных фталимидов, связанных с цимантренильным фрагментом, методами ИК- и ЯМР-спектроскопии, электронной спектроскопии поглощения и циклической вольтамперометрии, а также при помощи DFT-расчетов. Показано, что на оптические, донорно-акцепторные и окислительно-восстановительные свойства металлоорганических фталимидов оказывает влияние введение заместителя как в положение 1 боковой цепи Ср -кольца цимантрена, так и в положение 4 бензольного кольца фталимида. При этом взаимодействие в темновых условиях дикарбонильных хелатов с внешними лигандами свидетельствует о хемилабильности связи Mn–O=C(имид).

The paper describes a new device that allows us to study the effect of ultraviolet irradiation on the electrorheological characteristics of new photosensitive materials based on colloidal polyimide systems containing SO3H (PI-I) and SO3Na (PI-II) groups. The samples were analyzed using rotational viscometry methods, and a significant effect of irradiation of the systems on the flow velocity and hence the viscosity of the medium and the electrorheological response was shown. At the same time, the dimensional and microrheological properties of colloidal polyimide systems in polar and nonpolar media under simultaneous ultraviolet irradiation and exposure to an electric field were monitored using IR spectroscopy and dynamic light scattering methods. The mobility and zeta potential of polyimide molecules were determined using a sensitive method of phase analysis of light scattering. It is shown that in almost all cases, irradiation of colloidal systems of polyimides led to the uncontrolled formation of larger particles, which decreased during the thermal reaction almost to the initial size, which indicates the stability of the studied systems to external influences (irradiation and electric current).

This study comprehensively investigates the efficiency of the formulation of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) copolymer in sol-gel syntheses as part of a multivariate experiment. A methodology-based response surface was used to estimate the influence of independent variables such as polymerization time and temperature, as well as the ratio of TEOS and APTES components on the surface charge response function and product yield, and in order to predict the best response values. Analysis of variance showed that when assessing the value of the zeta potential, the polymerization temperature and the ratio of components are statistically significant factors, but on the other hand, when assessing the yield of the finished product, only the ratio of components is significant. The combination of various options for temperature, time and ratio of components allows one to obtain a zeta potential in the range from +61.2 mV to -48.8 mV and a product yield of up to 4.7 g. Evaluation of the data with TGA-DTA, FTIR-ATR, and ELS methods showed an unexpected result, according to which the highest degree of polymerization and the highest surface charge were inherent in an amino-deficient system. Thus, the smaller the amino component in the system (the APTES-TEOS molar ratio is 0.25), the more efficient the polycondensation is over the absorption area of the Si-O-Si band, and the higher the zeta potential.

New anisotropic silicone magnetoactive composites were synthesized and studied. The surface structure and filler microdimensions in these elastomers were determined by electron microscopy. The atomic force microscopy use made it possible to determine significant surface deformations and magnetostrictive effects when small external magnetic fields are applied to the composites. Mössbauer spectroscopy on iron isotope nuclei made it possible to identify the fillers hyperfine parameters.

Photochemical properties of symmetrical pyromellitic diimide containing two cymantrenyl fragments at two nitrogen atoms were studied with IR, NMR, UV-vis, ESI-MS, and cyclic voltammetry. It was found that new unstable chelates are formed during photolysis. At the same time, the CO ligand dissociates from two Mn(CO)3 fragments during photoexcitation, which dramatically changes the electronic and redox properties of the molecule compared to the cymantrene derivative containing one imide fragment. Photolysis leads to a color change from light yellow to green. DFT calculations confirmed the possibility of the formation of complexes due to the loss of one or two CO ligands from manganese atoms. The results obtained with variation of photolysis conditions demonstrated the hemilabile character of the Mn-O=C(imide) bond. On addition of external ligands, the color and electrochemical properties changed, which is promising for the use of this complex as a sensor for small molecules.

Cyclopentadienyl manganese tricarbonyl (cymantrene) is known to undergo photochemical reactions by releasing one of its CO ligands. Here we present the first example of a photorearrangement of a cymantrenylmethyl fragment, where it retains all its three CO ligands. A tandem experimental and DFT (density functional theory)-based computational investigation allows us to explain this unexpected behavior: the rearrangement, indeed, begins with the release of one CO ligand, but cage effect of the solvent captures this CO molecule, allowing it to rapidly reattach once the rearrangement takes place.

For the first time, the possibility of photoinduced migration of the cymantrenylmethyl fragment in O-substituted quinazolinones from position 4 to 3 of the quinazolinone ring under irradiation with light by a mercury lamp having λmax = 365 nm is found. We have explored this possibility for carrying out the isomerization of the N-substituent in 1,2,3-triazoles as a new way to obtain 2,4-disubstituted 1,2,3-triazoles.

For the first time, the photo- and thermochemical properties of cymantrenylalkylthiols 1 and 2 were studied. It was found that thiol 1 is an unstable compound and enters into a spontaneous dimerisation reaction. Photolysis of new compound 5 in DMF resulted in the replacement of the CO ligand with one solvent molecule. The photolysis of thiol 2 led to the formation of intramolecular complexes 7 and R2. The parameters of the IR, NMR and UV-visible spectra changed after irradiation of 2. In the presence of CO, these chelates were converted to the starting tricarbonyl compounds, thereby forming an intermolecular photochromic system.

Photolysis of di(cymantrenylalkyl)disulfides was studied by IR, 1 H NMR and UV-vis spectroscopy. Irradia-tion of cymantrenes with a disulfide bridge results in the formation of two type dicarbonyl chelates with Mn-S bond. The first type is formed due to removal of one CO ligand from one cymantrenyl moiety to give a 5-membered chelate cycle; the other is formed due to removal of two CO ligands from two cy-mantrenyl moieties to form a bicyclic chelate. The latter was isolated and characterized by X-ray analysis. For the first time, unstable fulvenes were prepared in situ by irradiation of cymantrenyl derivatives or their dicarbonyl complexes. Electrochemical properties of disulfides were studied before and after pho-tolysis in acetonitrile. The manganese oxidation potential value increased on going from tricarbonyls to dicarbonyls.(C) 2022 Elsevier B.V. All rights reserved.

The article describes the main properties and applications of tri- and dicarbonyl derivatives of cymantrene bearing a C=O donor fragment capable of coordinating with manganese atoms. Recent reports of different research groups, including our, show that these compounds can be of interest for the creation of photosensitive smart materials owing to the possibility of formation of photochromic systems between hemilabile di- and tricarbonyl complexes. The properties of these complexes of cymantrene with ketone, amide, and carbamate groups of both monomeric and cascade structures are considered.

Magnetite (Fe3O4) nanoparticles (NPs) have widely used in various fields, including in medicine, due to their (super)paramagnetic properties. This requires a thorough evaluation of their possible hazardous effects. However, there is no standard procedure for the preparation of oxidation-prone NPs (such as magnetite) before subjecting them to biological assays. In this study we used Fe3O4 NPs (bare and silica-coated) as test samples to compare different preparation methods (ultrasound, centrifugation and filteration of NPs suspensions) based on X-ray and dynamic light scattering analysis and evaluation of microstructure and surface charge. After oxidation and functionalization, all samples retained their superparamagnetic behaviour. The toxicity of NP suspensions obtained by the methods described for Paramecium caudatum ciliates and Sinapis alba plants was evaluated.

Suspensions of polyimide particles were obtained, in which 2,5-diaminobenzenesulfonic acid was used as a diamine component. Their electrorheological properties in a nonconducting medium were studied depending on the parameters of deformation and the intensity of the external electric field. It is established that the electro-rheological suspensions obtained based on particles of polyimide PI-I–PI-IV have a powerful electro-rheological response, ten times higher than the electro-rheological effect of suspensions based on traditional micro-sized particles of the dispersed phase.