1,1,4,4-Tetramethylbutane-1,4-diyl substituent fused to positions 5,6 of 2,3-dihydroxybezaldehyde ('catecholcarbaldehyde') upon the action of acids readily moves to positions 3,4 to afford less strained isomer, with the optimum reagent being neat methanesulfonic acid acting at room temperature. The same compound was prepared in four steps from 3,4-(1,1,4,4-tetramethylbutane-1,4-diyl)phenol; the intermediates were the mixtures of 3,4-and 4,5-fused o-benzoquinones/catechols whereas the last step involved the abovementioned substituent moving.

The possibility of using rare earth metal cations (Y3+, La3+, Nd3+, and Sm3+) as gel-forming agents for sodium alginate to obtain hydrogels for biomedical purposes was investigated. It was found that hydrogel microspheres based on rare earth metal ions have a denser crosslinking and are more stable to the leaching of the crosslinking agent upon repeated washing in physiological saline compared to microspheres based on barium alginate. However, hydrogel microspheres crosslinked with rare earth metal cations gradually degrade in blood serum and Hank’s solution due to the presence of sodium bicarbonate in these media. It was also established that gel-forming solutions of rare earth metal salts [SmCl3, Nd(AcO)3, LaCl3, and YCl3] at concentrations up to 20 mmol/L do not exhibit critical cytotoxic effects on cell culture.

In this paper, we consider a series of new compact A-π-D photoinitiators consisting of donor aromatic fragments (naphthalene, anthracene, phenanthrene, pyrene and perylene) and a strong acceptor tricyanoethylene group—aryltricyanoethylenes (ArTCNEs). Spectral, photophysical, and electrochemical characteristics of ArTCNEs are studied. One-photon (with LED@405 nm) and two-photon (λ = 780 nm, impulse duration of 100 fs) photopolymerization of PETA can be effectively initiated by ArTCNEs with the tertiary amine N,N-dimethylcyclohexylamine DMCHA and/or the iodonium salt diphenyliodonium chloride Iod. Based on results of experiments on photodegradation, photopolymerization and EPR spectroscopy, a photoinitiation mechanism of radical photopolymerization was proposed for two-component (AntTCNE/DMCHA) and three-component (AntTCNE/DMCHA/Iod) initiating systems. The composition containing PerTCNE/DMCHA as a photoinitiator demonstrated the best reactivity under two-photon nanolithography conditions: the polymerization threshold was 2 mW at a laser beam scanning speed of 100 μm/s, and the widest fabrication window of 11 mW was typical for it. As an example, 3D “cage” structures were fabricated using the AntTCNE-based composition, and the test structure resolution parameters, such as the minimum line width and the distance between lines of 80 and 400 nm, respectively, were achieved. MTT experiments with human dermal fibroblasts showed promising preliminary biocompatibility of the resulting polymers, which opens up possibilities for using the obtained materials in biological applications.

A series of trialkyl-substituted o-benzoquinones has been synthesized and studied. This class of compounds are Norish II-type photoinitiators used in photo-curing technology. Their reactivity in photoreduction and polymerization inhibition reactions is determined. The photoinitiating properties of this series of o-benzoquinones in the presence of N,N-dimethylethanolamine (DMAE) were studied using the example of cured dimethacrylate resins (OCM-2, TEGDMA) under irradiation with light >500 nm. Changing the alkyl substituents in position 6 from primary (Q(6)(Et), Q(7)(Me)) to tertiary (Q(1)(Ad)-Q(3)(t-Bu)) significantly increases the efficiency of o-quinones as photoinitiators, in particular, the maximum rate of photopolymerization of TEGDMA increases by 8 times. Quinone Q(3)(t-Bu) proved to be the most effective photoinitiator among the obtained derivatives and is a more effective initiator than the well-known 3,6-di-tert-butyl-o-benzoquinone in both TEGDMA and OCM-2. Furthermore, the photoinitiating systems based on o-quinone/amine has effective photobleachable and low absorbtion in the 500-650 nm region, which is promising for their use for curing thick films. Thick samples of poly TEGDMA (3.5 cm thickness) with and without the additional yellow or red dyes were obtained from PCC based on Q(3)(t-Bu)/DMAE by irradiating the LED Warm White (25 mW/cm(2)) for 20 min.

Two new A-pi-D-type photoinitiators based on indane-1,3-dione with methacrylate Dye 2 and isobutyrate Dye 3 groups were synthesized and characterized by NMR, IR- and UV-Vis spectroscopy. The spectral, photoluminescent and electrochemical properties of Dye 2 and Dye 3 compounds were investigated. Compounds Dye 2 and Dye 3 with tertiary amines N,N-dimethylaniline (DMA), N,N-dimethylcyclohexylamine (DMCHA) initiate both one- (LED with lambda = 405 nm) and two-photon (lambda = 780 nm and scale of impulse duration 100 fs) photopolymerization of PETA. The polymerization threshold of the Dye 2-based composition (Dye 2-DMA-PETA) under two-photon initiation conditions was 6.5 mW at a scanning speed of 100 mu m/s. Cage-like scaffold structures were fabricated by DLW-nanolithography using Dye 2 and Dye 3-based compositions. Structures with a line thickness of 90 nm located at a distance of 220 nm were obtained from the Dye 2-DMCHA-PETA composition, and for the Dye 3-DMCHA-PETA composition lines with a thickness of 140 nm at a distance of 310 nm were obtained. Due to the presence of methacrylate groups, Dye 2 has the ability to link into polymer networks and improves the thermal and physical-mechanical characteristics of polymers and increases the printing resolution under two-photon photopolymerization conditions. Additionally, it reduces the migration of the photoinitiator from the polymer matrix, compared to Dye 3. These advantages will allow the development of photopolymerizable compositions and biocompatible polymers based on them with high thermal stability and physical and mechanical characteristics.

A series of 4-hydroxy-4,9-dihydro-4H-xanthen-4-one derivatives were synthesized using the oxidative cyclization reaction of space-shielded catecholphenols. The structure of 1,3,5,7-tetra-tert-butyl-4a,8-dihydroxy-9H-xanthen-4(4aH)-one was determined by X-ray diffraction analysis (CCDC 2345899). The antiradical properties of new compounds were studied by their reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH radical).

The possibility of using a series of methacrylate-containing N,N-diethyl-4-(phenyldiazenyl)anilines with various para-substituents (–H, –Br, –NO2) relative to the azo group as photoinitiators of radical polymerization is considered. The electrochemical and photoluminescent properties of these compounds have been studied. In the presence of azo dyes, two-photon photopolymerization of pentaerythritol triacrylate was carried out using focused 780-nm radiation from a femtosecond laser. Structures with minimal dimensions of linear elements of 94 ± 5 nm were obtained by means of the DLW nanolithography technique, and 3D microstructures of complex architecture were fabricated.

The development of photocurable compositions is in high demand for the manufacture of functional materials for electronics, optics, medicine, energy, etc. The properties of the final photo-cured material are primarily determined by the initial mixture, which needs to be tuned for each application. In this study we propose to use simple systems based on di(meth)acrylate, polyimide and photoinitiator for the preparation of new photo-curable compositions. It was established that a fluorinated cardo copolyimide (FCPI) based on 2,2-bis-(3,4-dicarboxydiphenyl)hexafluoropropane dianhydride, 9,9-bis-(4-aminophenyl)fluorene and 2,2-bis-(4-aminophenyl)hexafluoropropane (1.00:0.75:0.25 mol) has excellent solubility in di(met)acrylates. This made it possible to prepare solutions of FCPI in such monomers, to study the effect of FCPI on the kinetics of their photopolymerization in situ and the properties of the resulting polymers. According to the obtained data, the solutions of FCPI (23 wt.%) in 1,4-butanediol diacrylate (BDDA) and FCPI (15 wt.%) in tetraethylene glycol diacrylate were tested for the formation of the primary protective coatings of the silica optical fibers. It was found that the new coating of poly(BDDA–FCPI23%) can withstand prolonged annealing at 200 °C (72 h), which is comparable or superior to the known most thermally stable photo-curable coatings. The proposed approach can be applied to obtain other functional materials.

A series of sterically hindered catecholphenols was synthesized by the reaction 4,6-di-tert-butyl-3-methoxymethylcatechol with resorcinol, 4,6-di-tert-butylresorcinol, orcinol, 3,5-dimethoxyphenol, α- and β-naphthol. The structure of the obtained compounds was proved by NMR, IR and mass spectroscopy. The structure of 4,6-di-tert-butyl-3-[(2-hydroxynaphthalen-1-yl)methyl]benzene-1,2-diol was determined by single-crystal X-ray diffraction. The radical scavenging of obtained compounds were determined using 2,2-diphenyl-1-picrylhydrazyl radical test.

The possibility of using water-soluble heteronuclear metallamacrocyclic complexes of Sr(II)–Cu(II), Ca(II)–Cu(II), and La(III)–Cu(II) as crosslinking agents for alginate hydrogels has been investigated for the first time. The possibility of ion-induced crosslinking of alginate with metallacrown cations has been experimentally demonstrated. Alginate hydrogel microspheres have been prepared via extrusion, using the metallacrowns as crosslinking agents. The degree of cross-linking of the hydrogels depends on the nature of the central element of the metallacrown. In terms of their crosslinking ability, the considered metallacrowns (MC(M)) are arranged in the following series: MC(La) > MC(Sr) > MC(Ca).

This paper provides a study of two bone substitutes: a hybrid porous polymer and an osteoplastic matrix based on a bovine-derived xenograft. Both materials are porous, but their pore characteristics are different. The osteoplastic matrix has pores of 300–600 µm and the hybrid polymer has smaller pores, generally of 6–20 µm, but with some pores up to 100 µm across. SEM data confirmed the porometry results and demonstrated the different structures of the materials. Therefore, both materials were characterized by an interconnected porous structure and provided conditions for the adhesion and vital activity of human ASCs in vitro. In an experimental model of rabbit shin bone defect, it was shown that, during the 6-month observation period, neither of the materials caused negative reactions in the experimental animals. By the end of the observation period, restoration of the defects in animals in both groups was completed, and elements of both materials were preserved in the defect areas. Data from morphological examinations and CT data demonstrated that the rate of rabbit bone tissue regeneration with the hybrid polymer was comparable to that with the osteoplastic matrix. Therefore, the hybrid polymer has good potential for use in further research and improvement in biomedical applications.

A series of trisubstituted o-benzoquinones containing a (3,5-dimethyl-1H-pyrazol-1-yl)methyl substituent at position 3 and two alkyl groups (i-Pr, c-Hex, t-Bu, Ad) at positions 4 and 6 were synthesized. Their structures were confirmed by IR, 1H, 13C NMR spectroscopy methods. The electrochemical properties of the o-quinones were investigated by cyclic voltammetry method. The radical polymerization of methyl methacrylate at 60°C in the presence o-quinone (0.62–2.48 mM) was studied. The inhibitory ability of new quinone decreases (i-Pr > c-Hex > t-Bu > Ad) with increasing of the Charton steric parameters of alkyl groups. The photoinitiating ability of the investigated quinones in pair with DMCHA were studied on the photocuring of OCM-2 by the LED@white (9.1 kLx). The photoinitiating ability of new quinone increase (i-Pr < c-Hex < t-Bu < Ad) with increasing of the Charton steric parameters of alkyl groups.

Hybrid porous polymers based on poly-EGDMA and polylactide containing vancomycin, the concentration of which in the polymer varied by two orders of magnitude, were synthesized. The processes of polymer biodegradation and vancomycin release were studied in the following model media: phosphate-buffered saline (PBS), trypsin-Versene solution, and trypsin-PBS solution. The maximum antibiotic release was recorded during the first 3 h of extraction. The duration of antibiotic escape from the polymer samples in trypsin-containing media varied from 3 to 22 days, depending on the antibiotic content of the polymer. Keeping samples of the hybrid polymer in trypsin-containing model media resulted in acidification of the solutions—after 45 days, up to a pH of 1.84 in the trypsin-Versene solution and up to pH 1.65 in the trypsin-PBS solution. Here, the time dependences of the vancomycin release from the polymer into the medium and the decrease in pH of the medium correlated. These data are also consistent with the results of a study of the dynamics of sample weight loss during extraction in the examined model media. However, while the polymer porosity increased from ~53 to ~60% the pore size changed insignificantly, over only 10 μm. The polymer samples were characterized by their antibacterial activity against Staphylococcus aureus, and this activity persisted for up to 21 days during biodegradation of the material, regardless of the medium type used in model. Surface-dependent human cells (dermal fibroblasts) adhere well, spread out, and maintain high viability on samples of the functionalized hybrid polymer, thus demonstrating its biocompatibility in vitro.

Porous polymer monoliths with thicknesses of 2 and 4 mm were obtained via polymerization of ethylene glycol dimethacrylate (EGDMA) under the influence visible-light irradiation in the presence of a 70 wt% 1-butanol porogenic agent and o-quinone photoinitiators. The o-quinones used were: 3,5-di-tret-butyl-benzoquinone-1,2 (35Q), 3,6-di-tret-butyl-benzoquinone-1,2 (36Q), camphorquinone (CQ), and 9,10-phenanthrenequinone (PQ). Porous monoliths were also synthesized from the same mixture but using 2,2′-azo-bis(iso-butyronitrile) (AIBN) at 100 °C instead o-quinones. According to the results of scanning electron microscopy, all the resulting samples were conglomerates of spherical, polymeric particles with pores between them. Use of mercury porometry showed that the interconnected pore systems of all the polymers were open. The average pore size, Dmod, in such polymers strongly depended on both the nature of the initiator and the method of initiation of polymerization. For polymers obtained in the presence of AIBN, the Dmod value was as low as 0.8 μm. For polymers obtained via photoinitiation in the presence of 36Q, 35Q, CQ, and PQ, the Dmod values were significantly greater, i.e., 9.9, 6.4, 3.6, and 3.7 μm, respectively. The compressive strength and Young’s modulus of the porous monoliths increased symbatically in the series PQ < CQ < 36Q < 35Q < AIBN with decreasing proportions of large pores (over 12 μm) in their polymer structures. The photopolymerization rate of the EGDMA and 1-butanol, 30:70 wt% mixture was maximal for PQ and minimal for 35Q. All polymers tested were non-cytotoxic. Based on the data from MTT testing, it can be noted that the polymers obtained via photoinitiation were characterized by their positive effect on the proliferative activity of human dermal fibroblasts. This makes them promising osteoplastic materials for clinical trials.

A novel sterically hindered o -benzoquinone 4,6-di- tert- butyl-3-(5,7-di- tert- butylbenzooxazole-2-yl)- o -benzoquinone containing a benzoxazole moiety is prepared. The interaction of this quinone with Cu(0) yielded a cubane copper(II) complex with a Cu 4 O 4 core. Molecular and crystal structures of the o -quinone (CCDC 2269708) and the copper complex (CCDC 2269709) are determined by XRD.

Six new 1-hexadecyl derivatives of isatin with various substituents at position 5 were synthesized. Their spectral and electrochemical characteristics were determined. All the obtained isatins can undergo photoreduction in solution in the presence of tertiary amines upon irradiation with visible light. The effective rate constant of the process increases with a decrease of the amine oxidation potential, an increase of the isatin reduction potential, and it reaches a maximum in the case of the bromo derivative. In the presence of triethylamine, the obtained 1-hexadecylisatins initiate a photopolymerization of dimethacrylate OCM-2 under the action of near UV and visible light in the blue spectral region. The rate constants of photoreduction and photopolymerization during the transition from one isatin to another change in parallel. The highest efficiency of photoinitiation of OCM-2 polymerization is exhibited by 5-bromo-1-hexadecylisatin.

In this work, we study the polymerization of methyl methacrylate in the presence of 0.3-1.2 wt% aerosil and the following initiators: dinitrile azo-bis-isobutyric acid together with tributylborane; dinitrile azo-bis-isobutyric acid together with tributylborane and 2,5-di-tret-butyl benzoquinone-1,4; tributylborane together with di-tret-butyl peroxy-triphenylstibine. Aerosil introduction alters the polymerization kinetics of methyl methacrylate and the respective IR spectra, indicating an increase in the proportion of syndiotactic polymer. This process is related to the orientation of the monomer and polymer on the filler surface due to adsorption by means of the carbonyl oxygen atom and silicon d-orbitals. Each initiating system has a particular effect on the kinetic curves. The polymerization of methyl methacrylate in the presence of tributylborane proceeds through coordination-radical polymerization in the coordination sphere of the boron atom. Additional coordination disrupts monomer coordination and slows down polymerization. The polymerization of methyl methacrylate in the presence of the tributylborane-p-quinone system combines the routes of coordination-radical polymerization and pseudo-living radical polymerization. The initiating system of tributylborane-di-tret-butyl peroxy-triphenylstibine is characterized by implementation of both physical and chemical adsorption mechanisms. The latter promotes the formation of a composite through covalent bonds between the polymer matrix (polymethyl methacrylate) and the filler (aerosil). An increase in the amount of aerosil up to 10 wt% leads to a corresponding change in the IR spectra of the composites. Laboratory samples were prepared to study the mechanical properties of composites and films. When filled with aerosil, polymethyl methacrylate demonstrate worse deformation properties, which is typical of composite materials. The microhardness of the material varies depending on the initiator used and the grafting type (physical or chemical), correlating with the kinetic data.

Di- tert -alkyl-substituted catechols with a heterocyclic imidazole-type substituent were synthesized in three steps from catecholaldehydes. The 1,1,4,4-tetramethylbutanediyl substituent was shown to be resistant to the action of acids in the demethylation reaction. The isomerization of 3,4,5-substituted catechols to the 3,4,6-substituted isomers was observed. The molecular structures of the synthesized compounds in the crystalline state were established by X-ray diffraction analysis. For the catechol derivatives, the tertiary substituent in the ortho position to the imidazole moiety was shown to have an effect on the mutual arrangement of the catechol and heterocyclic moieties. The electrochemical properties of the synthesized imidazole-containing catechols were studied and their anti-radical activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl assay.

Синтезирован новый пространственно-экранированный о-бензохинон содержащий бензоксазольный фрагмент - 4,6-ди-трет-бутил-3-(5,7-ди-трет-бутилбензооксазол-2-ил)-о-бензохинон. Взаимодействием данного хинона с Cu(0) получен кубановый комплекс меди (II), содержащий ядро Cu4O4. Молекулярное и кристаллическое строение о-хинона (CCDC 2269708) и комплекса меди (CCDC 2269709) установлено методом РСА.