Metal and Metal Oxides Nanoparticles and Nanosystems in Anticancer and Antiviral Theragnostic Agents.

The development of antiviral treatment and anticancer theragnostic agents in recent decades has been associated with nanotechnologies, and primarily with inorganic nanoparticles (INPs) of metal and metal oxides. The large specific surface area and its high activity make it easy to functionalize INPs with various coatings (to increase their stability and reduce toxicity), specific agents (allowing retention of INPs in the affected organ or tissue), and drug molecules (for antitumor and antiviral therapy). The ability of magnetic nanoparticles (MNPs) of iron oxides and ferrites to enhance proton relaxation in specific tissues and serve as magnetic resonance imaging contrast agents is one of the most promising applications of nanomedicine.

Liquid-like and solid-like acetonitrile intercalated into graphite oxide as studied by the spin probe technique.

The molecular mobility of acetonitrile intercalated into the inter-plane space of graphite oxide was studied using the spin probe technique. It was revealed that two types of intercalated substance - liquid-like and solid-like - are simultaneously present in between the oxidized graphene planes, and their ratio depends on temperature. The micro-viscosity of liquid-like intercalated acetonitrile was found to be higher than that of bulk acetonitrile and depends on the amount of intercalated liquid.

Structure and Dynamics of Inhomogeneities in Aqueous Solutions of Graft Copolymers of N-Isopropylacrylamide with Lactide (P(NIPAM--PLA)) by Spin Probe EPR Spectroscopy.

Coil-to-globule transition and dynamics of inhomogeneities in aqueous solutions of graft copolymers of NIPAM with different content of oligolactide groups were studied using spin probe continuous wave EPR spectroscopy. The technique of the suppressing of TEMPO as spin probe by spin exchange with Cu ions was applied. This approach allowed us to detect individual EPR spectra of the probe in collapsed globules and estimate its magnetic and dynamic parameters reliably.

Cryostructuring of Polymeric Systems: 62 Preparation and Characterization of Alginate/Chondroitin Sulfate Cryostructurates Loaded with Antimicrobial Substances.

Targeted drug release is a significant research focus in the development of drug delivery systems and involves a biocompatible polymeric carrier and certain medicines. Cryostructuring is a suitable approach for the preparation of efficient macroporous carriers for such drug delivery systems. In the current study, the cryogenically structured carriers based on alginate/chondroitin sulfate mixtures were prepared and their physicochemical properties and their ability to absorb/release the bactericides were evaluated.

Copper coordination compounds with (5,5')-2,2'-(alkane-α,ω-diyldiselenyl)-bis-5-(2-pyridylmethylene)-3,5-dihydro-4-imidazol-4-ones. Comparison with sulfur analogue.

A series of new organic ligands (5,5')-2,2'-(alkane-α,ω-diyldiselenyl)-bis-5-(2-pyridylmethylene)-3,5-dihydro-4-imidazol-4-ones (L) consisting of two 5-(2-pyridylmethylene)-3,5-dihydro-4-imidazol-4-one units linked with polymethylene chains of various lengths ( = 2-10, where is the number of CH units) have been synthesized. The reactions of these ligands with CuCl·2HO and CuClO·6HO gave Cu or Cu containing mono- and binuclear complexes with CuLCl ( = 2-4) or CuL(ClO) ( = 1, 2) composition. It was shown that the agents reducing Cu to Cu in the course of complex formation can be both a ligand and an organic solvent in which the reaction is carried out.

Inhomogeneities in PNIPAM Aqueous Solutions: The Inside View by Spin Probe EPR Spectroscopy.

Coil to globule transition in poly(N-isopropylacrylamide) aqueous solutions was studied using spin probe continuous-wave electronic paramagnetic resonance (CW EPR) spectroscopy with an amphiphilic TEMPO radical as a guest molecule. Using Cu(II) ions as the "quencher" for fast-moving radicals in the liquid phase allowed obtaining the individual spectra of TEMPO radicals in polymer globule and observing inhomogeneities in solutions before globule collapsing. EPR spectra simulations confirm the formation of molten globules at the first step with further collapsing and water molecules coming out of the globule, making it denser.

Intramolecular photo-driven charge transfer in a series of pyridyl substituted phenyloxazoles. Structural relaxation in meta-substituted ethylpyridinium derivative of phenyloxazole.

A series of pyridyl (pyridinium) substituted benzoxazoles were studied by steady state absorption, fluorescence spectroscopy, time-resolved fluorescence spectroscopy, fs pulse absorption and polarization spectroscopy, and quantum-chemical calculations. The spectral and kinetic parameters of the fluorophores in MeCN and EtOAc were obtained experimentally and were calculated by means of DFT and TDDFT methods. A scheme including four transient excited states was proposed for the interpretation of differential absorption kinetics of the charged fluorophores.

Solute Diffusion into Polymer Swollen by Supercritical CO by High-Pressure Electron Paramagnetic Resonance Spectroscopy and Chromatography.

High-pressure electron paramagnetic resonance (EPR) was used to measure translational diffusion coefficients (D) of a TEMPONE spin probe in poly(D,L-lactide) (PDLLA) and swollen in supercritical CO. D was measured on two scales: macroscopic scale (>1 μm), by measuring spin probe uptake by the sample; and microscopic scale (<10 nm), by using concentration-dependent spectrum broadening. Both methods yield similar translational diffusion coefficients (in the range 5-10 × 10 m/s at 40-60 °C and 8-10 MPa).

Polymorphism and Conformational Equilibrium of Nitro-Acetophenone in Solid State and under Matrix Conditions.

Conformational and polymorphic states in the nitro-derivative of -hydroxy acetophenone have been studied by experimental and theoretical methods. The potential energy curves for the rotation of the nitro group and isomerization of the hydroxyl group have been calculated by density functional theory (DFT) to estimate the barriers of the conformational changes. Two polymorphic forms of the studied compound were obtained by the slow and fast evaporation of polar and non-polar solutions, respectively.

New Insight into the Mechanism of Drug Release from Poly(d,l-lactide) Film by Electron Paramagnetic Resonance.

A novel approach based on convolution of the electron paramagnetic resonance (EPR) spectra was used for quantitative study of the release kinetics of paramagnetic dopants from poly(d,l-lactide) films. A non-monotonic dependence of the release rate on time was reliably recorded. The release regularities were compared with the dynamics of polymer structure changes determined by EPR, SEM, and optic microscopy.

Novel Copper-Containing Cytotoxic Agents Based on 2-Thioxoimidazolones.

A series of 73 ligands and 73 of their Cu and Cu copper complexes with different geometries, oxidation states of the metal, and redox activities were synthesized and characterized. The aim of the study was to establish the structure-activity relationship within a series of analogues with different substituents at the N(3) position, which govern the redox potentials of the Cu/Cu redox couples, ROS generation ability, and intracellular accumulation. Possible cytotoxicity mechanisms, such as DNA damage, DNA intercalation, telomerase inhibition, and apoptosis induction, have been investigated.

Femtosecond excited state dynamics of stilbene-viologen complexes with a weakly pronounced charge transfer.

The femtosecond dynamics of photoinduced electron transfers in supramolecular donor-acceptor complexes between (E)-bis(18-crown-6)stilbene (D) and tetraperchlorates of 2,7-di(2-ammonioethyl)(2,7-diazapyrenium) (A1), 3,3'-(E)-ethene-1,2-diylbis[1-(3-ammoniopropyl)pyridinium] (A2) and 4,4'-ethane-1,2-diylbis[1-(3-ammoniopropyl)pyridinium] (A3) was studied. The acceptors A2 and A3 are weak electron acceptors whose first reduction potentials are equal to -1.0 and -1.

Influence of succinylation of a wide-pore albumin cryogels on their properties, structure, biodegradability, and release dynamics of dioxidine loaded in such spongy carriers.

The goal of this study was to reveal how the chemical modification, succinylation in this case, of the wide-pore serum-albumin-based cryogels affects on their osmotic characteristics (swelling extent), biodegradability and ability to be loaded with the bactericide substance - dioxidine, as well as on its release. The cryogels were prepared via the cryogenic processing (freezing - frozen storage - thawing) of aqueous solutions containing bovine serum albumin (50 g/L), denaturant (urea or guanidine hydrochloride, 1.0 mol/L) and reductant (cysteine, 0.

Sterically hindered Re- and Mn-CO reduction catalysts for solar energy conversion.

Novel molecular Re and Mn tricarbonyl complexes bearing a bipyridyl ligand functionalised with sterically hindering substituents in the 6,6'-position, [M(HPEAB)(CO)3(X)] (M/X = Re/Cl, Mn/Br; HPEAB = 6,6'-{N-(4-hexylphenyl)-N(ethyl)-amido}-2,2'-bipyridine) have been synthesised, fully characterised including by single crystal X-ray crystallography, and their propensity to act as catalysts for the electrochemical and photochemical reduction of CO2 has been established. Controlled potential electrolysis showed that the catalysts are effective for electrochemical CO2-reduction, yielding CO as the product (in MeCN for the Re-complex, in 95 : 5 (v/v) MeCN : H2O mixture for the Mn-complex). The recyclability of the catalysts was demonstrated through replenishment of CO2 within solution.

Chameleon-Like Activating Nature of the Spirooxindole Group in Donor-Acceptor Cyclopropanes.

The concept of a chameleon activating group is considered in the context of donor-acceptor cyclopropane chemistry. When spiro-conjugated with cyclopropane, oxindole can act as an acceptor or a donor depending on the electronic nature of vicinal substituents. This dichotomy is reflected in the alteration of chemoselectivity of spiro[oxindole-1,3'-cyclopropane] ring opening with nucleophiles.

Phosphazenomalonates as Catalysts and Reactants in (4+3) Annulation to Acrolein.

The concept of combining a catalyst and an activated center in one molecule was implemented in Michael donors functionalized with phosphazene units. First, the phosphazene group catalyzes Michael addition and then acts as a reactant in an intramolecular aza-Wittig reaction. The viability of this strategy was demonstrated by our development of a one-pot method for azepane core construction starting from functionalized azides, triphenylphosphine and acrolein.

Stereocontrolled [3+2] Cycloaddition of Donor-Acceptor Cyclopropanes to Iminooxindoles: Access to Spiro[oxindole-3,2'-pyrrolidines].

A novel stereocontrolled assembly of spiro[oxindole-3,2'-pyrrolidines] via [3+2]-cycloaddition of donor-acceptor cyclopropanes to electron-poor ketimines, iminooxindoles, was developed. The method allows for efficient employment of common readily available donor-acceptor cyclopropanes, functionalized with ester, keto, nitro, cyano etc. groups, and N-unprotected iminooxindoles.

aza-Wittig Reaction with Nitriles: How Carbonyl Function Switches from Reacting to Activating.

Transformations of α-EWG-substituted (electron-withdrawing group, EWG) γ-azidobutyronitriles proceeding via unusual aza-Wittig reactions between the phosphazene and nitrile functions and affording pyrrole-derived iminophosphazenes were developed. α-EWGs were found to control chemoselectivity and, depending on their nature, act as CN group activators (e.g.

Formation of a supramolecular charge-transfer complex. Ultrafast excited state dynamics and quantum-chemical calculations.

The formation of a supramolecular complex of bis(18-crown-6)stilbene (1) and 4,4'-bipyridine with two ammoniopropyl N-substituents (3) and the substitution reaction between 1·3 and alkali and alkaline-earth metal perchlorates have been studied using absorption, steady-state fluorescence, and femtosecond transient absorption spectroscopy. The formation of 1·(M) complexes in acetonitrile was demonstrated. The weak long-wavelength charge-transfer absorption band of 1·3 completely vanishes upon complexation with metal cations because of disruption of the pseudocyclic structure.

Nucleophilic Ring Opening of Donor-Acceptor Cyclopropanes with the Cyanate Ion: Access to Spiro[pyrrolidone-3,3'-oxindoles].

The nucleophilic ring opening of donor-acceptor cyclopropanes with the cyanate ion is reported for the first time. Cyclopropanes, spiro-activated with oxindole fragments as acceptors, are shown to undergo transformations into biologically relevant spiro[pyrrolidone-3,3'-oxindoles] while being treated with potassium cyanate under microwave assistance.

Donor-acceptor cyclopropanes as ortho-quinone methide equivalents in formal (4 + 2)-cycloaddition to alkenes.

A new type of donor-acceptor cyclopropane reactivity towards alkenes was revealed for 2-arylcyclopropane-1,1-diesters that contain an OH-group in the ortho-position of the aryl substituent. In this case, the initial cyclopropanes participate in formal (4 + 2)-cycloaddition as synthetic equivalents of ortho-quinone methides which are potential intermediates generated under mild conditions in the presence of a Lewis acid.

Femtosecond excited state dynamics of a stilbene-viologen charge transfer complex assembled via host-guest interaction.

The dynamics of the excited states of a supramolecular complex with a charge transfer between (E)-bis(18-crown-6)stilbene and 4,4'-(E)-ethene-1,2-diylbis[1-(2-ammonioethyl)pyridinium]tetraperchlorate was studied by means of femtosecond transient spectroscopy. It is found that the characteristic time of the conversion of the locally excited (LE) state into the charge transfer (CT) state is equal to 300 fs, whereas the characteristic time of the conversion of the CT state into the ground state is equal to 400 fs. Due to host-guest interaction involving hydrogen bonds, the complex possesses high thermodynamic stability.

Regioselective Hydrogenolysis of Donor-Acceptor Cyclopropanes with Zn-AcOH Reductive System.

A convenient low-cost method for regioselective ring-opening of donor-acceptor cyclopropanes with the Zn-AcOH reductive system was developed. The general character of the method was displayed via efficient reduction of a representative series of 2-(het)arylcyclopropane-1,1-diesters as well as donor-acceptor cyclopropanes with other types of electron-withdrawing activating groups. This method opens a rapid access to γ-substituted propyl-1,1-diesters, ketoesters, cyanoesters, cyanoamides, dinitriles, etc.

Dynamics of excited-state intramolecular proton-transfer in 2-amino-3-(2'-benzazolyl)quinoline cations.

It was found that cations formed by the protonation of 2-amino-3-(2'-benzoxazolyl)-quinoline (ABO) and 2-amino-3-(2'-benzothiazolyl)-quinoline (ABT) at the nitrogen atom of the quinoline ring exhibit excited-state intramolecular proton transfer (ESIPT). The two-band fluorescence of these cations is due to the emission from two species: the initial tautomer (short-wavelength band) and the ESIPT product (long-wavelength band). The relative intensity of the long-wavelength band depends on the basicity of the proton-accepting moiety and temperature.

3-(2-Azidoethyl)oxindoles: Advanced Building Blocks for One-Pot Assembly of Spiro[pyrrolidine-3,3'-oxindoles].

A new synthetic approach to biologically relevant spiro[pyrrolidine-3,3'-oxindoles] was developed on the basis of the cascade transformation of 3-(2-azidoethyl)oxindoles via Staudinger/aza-Wittig/Mannich reactions. The parent azides were readily synthesized through a nucleophilic ring opening of spiro[cyclopropane-1,3'-oxindoles] with the azide ion. A series of new spiro[pyrrolidine-3,3'-oxindoles] with various (het)aryl substituents at the C2 and C5 positions of the pyrrolidine ring were synthesized.