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Using a theoretical approach supported by DFT calculations, the features of molecular structure of isomer 17418 (C1) of fullerene C76 with the distribution of single, double and delocalized π-bonds...

The dependence of the level of antimicrobial activity of some ammonium isatin-3-acylhydrazones on the sterical hindrance and electronic nature of substituents in the benzyl moiety was elucidated using simple molecular descriptors and quantum chemical calculations. The structure and electronic nature of substituents in position 1 and the lipophilicity of compounds of this series were shown to be the key factors determining the activity.

The molecular structures of non-IPR C40 fullerene isomers 31 (Cs), 38 (D2) and 39 (D5d) were studied using a semiempirical approach developed earlier for higher fullerenes. Quantumchemical calculations (DFT) showed that they have closed shells. The distributions of single, double and delocalized π bonds in the test isomer molecules and their molecular formulas are presented for the first time.

The formation of stable complexes of citrus pectin with nonsteroidal anti-inflammatory drugs, ibuprofen and acetylsalicylic acid (aspirin), was confirmed by IR and NMR spectro scopy. The stoichiometry of complexes with the maximum content of drugs (15 wt. %) was established. A comparative study of the thermal decomposition of pectin and the synthesized complexes with ibuprofen and acetylsalicylic acid was performed by TG/DSC.

The vibrational spectra of p-sulfonatocalix [4] arene were studied. The geometrical parameters, the energies, the frequencies and the intensities of the bands in the IR and Raman spectra are calculated for four conformations. The most stable conformation of the p-sulfonatocalix[4]arene is the cone due to the cooperative cyclic intramolecular hydrogen bonding system. The strength of the hydrogen bonds depends on the type of substituent on the upper rim of the calixarene molecules. We studied the process of destruction of calixarenes using IR spectroscopy and TGA methods. Characteristic bands for each conformation were selected. HOMO covers aromatic units with notable conjugation, and LUMO belongs to sulfonate groups.

MCM-41 type mesoporous silica particles were obtained using a template method in an alkaline medium and cetyltrimethylammonium bromide as a matrix. The structural and adsorption characteristics of the mesoporous material were studied by dynamic light scattering, scanning electron microscopy, low-temperature adsorption—desorption of nitrogen, IR spectroscopy, and simultaneous thermal analysis. It was shown that the obtained mesoporous material possesses high porosity with the specific pore volume in excess of 1 cm3 g−1. It was established that the size of silica particles does not exceed 200 nm, which is a value acceptable for the penetration of drugs through cell membranes. The optimal compositions of aqueous dispersions of MCM-41 with minimal sedimentation processes were determined. A drug (indomethacin) was encapsulated into the silica pores using the precipitation method at various temperatures (40 and 60 °C), the quantitative parameters of loading efficiency were calculated. The infl uence of temperature on the encapsulation ability was demonstrated.

It is well-known that the small non-IPR fullerenes Cn (n

A series of novel 4-aminobenzofuroxan derivatives containing aromatic/aliphatic amines fragments was achieved via aromatic nucleophilic substitution reaction of 4,6-dichloro-5-nitrobenzofuroxan. The quantum chemistry calculations were performed to identify the factors affecting the regioselectivity of the reaction. The formation of 4-substituted isomer is favored both by its greater stability and the lower activation barrier. Antimicrobial activity of the obtained compounds has been evaluated and some of them were found to suppress effectively bacterial biofilm growth. Fungistatic activity of 4-aminobenzofuroxans were tested on two genetically distinct isolates of M. nivale. The effect of some benzofuroxan derivatives is likely to be more universal against different varieties of M. nivale compared with benzimidazole and carbendazim. Additionally, their anti-cancer activity in vitro has been tested. 4-aminofuroxans possessing aniline moiety showed a high selectivity towards MCF-7 and M-HeLa tumor cell lines. Moreover, they exhibit a significantly lower toxicity towards normal liver cells compared to Doxorubicin and Tamoxifen. Thus, benzofuroxans containing aromatic amines fragments in their structure are promising candidates for further development both as anti-cancer and anti-microbial agents.

Here for the first time, we applied approach developed earlier for higher fullerenes to investigate the features of molecular structures of non-IPR isomers 270 (D3) and 271 (D5h) of small fullerene C50. The bond distributions are presented as structural formulas. The instability of the studied isomers is caused by a significant local overstrain due to the excessive folding of pentagons in pentalene fragments, which typically are planar molecules. It is found that the chains of π-bonds are passing through some cycles like in the previously studied higher non-IPR fullerenes C66 and C68. Chemical shifts of the centers of the pentagons and hexagons (NICS(0)) are reported. It is shown that chlorine atoms in the exohedral derivative C50Cl10 of isomer 271 (D5h) are attached to the indacene-like substructures confirming the preference of addition to π-delocalized hexagons in radical reactions. The identified features in the structures of smaller fullerene molecules can be predictive of the ability to be synthesized as derivatives and will assist in determination of their reactivity.

Two chromophores with π-deficient quinoxaline (Q) core in the π-electron bridge together with dibutylaniline (DBA) donor moiety and tricyanofuranyl (TCF) or dicyanovinyl (DCV) acceptor moieties have been synthesized to investigate their macroscopic nonlinear optical (NLO) activity in guest-host materials. A distinctive feature of the 7-DBA-VQPhV-TCF chromophore is predominance of negative solvatochromism over the positive one, which is quite rarely met for the chromophores manifesting inverse solvatochromic behavior as well as the blue shift of the absorption maximum compared to the chromophore FTC with divinylthiophene π-bridge. Introduction of quinoxaline moiety in the conjugated bridge promotes the increase of thermal stability: Td of both compounds is higher than 225 °C. Density functional theory was used to calculate the chromophores first hyperpolarizability (β). Quadratic NLO response characterized by d33 coefficient was measured by SHG technique for thin guest-host polymer films. The influence of chromophore content on the NLO coefficient of 7-DBA-VQPhV-TCF/PMMA film has been investigated and the d33 value of this film reaches 108 pm/V at 25 wt% load. The poled film 7-DBA-VQPh-DCV/PMMA shows twice smaller d33 values (30 pm/V) at the same chromophore load (20 wt%).

Among higher fullerenes that obey the isolated pentagon rule (IPR), there is an appreciable share of fullerenes with open electron shells. For a long time, this rule was used as a criterion for ful...

Two novel chromophores with dibutylaniline donor moiety, 3,7-(di)vinylquinoxalinone π-electron bridge and tricyanofuranyl or dicyanovinyl acceptor moieties are synthesized and their properties were systematically investigated. Atomistic modeling of PMMA-based composites with the developed chromophores as guests is performed and nonlinear optical activity is studied for the first time. Atomistic modeling performed in the amorphous cell has shown that chromophore content 20 wt% may be considered most favorable for achievement of optimal d33 values for 7-DBA-VQonV-TCF/PMMA material. Various non-covalent interactions both between chromophores and polymer matrix and chromophores inter se were revealed in the course of modeling; these interactions could contribute to the relaxation stability of orientational order and thus quadratic NLO response. Composite material 7-DBA-VQonV-TCF/PMMA is characterized by nonlinear-optical coefficient, d33, values of 97, 111 and 47 pm/V at chromophore content of 10, 20 and 30 wt%, respectively. Thus chromophore content 20 wt% provides maximal value of NLO coefficient, what is in agreement with the obtained theoretical data. The d33 value for 7-DBA-VQonV-DCV/PMMA is 2.5 times smaller than that for 7-DBA-VQonV-TCF/PMMA at the same chromophore load (20 wt%).

For the first time the nonlinear optical (NLO) activity of indolizine-based push-pull chromophores with different acceptor moieties was studied and compared. All the chromophores demonstrate strong absorption band in the visible (orange-red) part of the spectrum, with e of ca. 105 L∙cm−1∙M−1 notably dependent on medium polarity. Replacement of Ph-TCF acceptor by Hex-TCP one results in twofold increase of the first hyperpolarizability value. Energy gaps estimated by electrochemical methods decrease in the series ΔE1a,b>ΔE3a,b>ΔE2a,b for compounds with Ph-TCF, DCM and Hex-TCP acceptors, respectively, good agreement with DFT estimations is obtained. The nonlinear optical coefficient for poled PMMA-based films, containing 20 wt% of isomeric indolizine chromophores with weaker dicyanomethylene (DCM) acceptor and with π- bridge expanded by isophorone moiety, achieves 36 pm/V, thus exceeding those for materials containing chromophores with stronger Ph-TCF or Hex-TCP acceptors and with short vinylene π-bridge.

Four chromophores belonging to a new class of push-pull chromophores with divinylphenylquinoxaline moieties have been designed and synthesized. The structure-property relationship was systematically investigated; the effect of the conformation on the value of chromophores first hyperpolarizability is found to be inessential. Quinoxaline-based chromophore with TCF acceptor and 7-dimethylanilinovinyl moiety displays the combination of favorable characteristics: the high value of the first hyperpolarizability, the small HOMO-LUMO energy gap, the blue shift of the absorption maximum relative to the chromophores with other divinylhetaryl or polyene π-bridges and ultrahigh thermal stability. This chromophore may be considered as a perfect candidate for the development of effective electro-optic materials.

Two series of isomeric indolizine-based chromophores with isophorone rings as a π-bridge have been synthesized and systematically investigated. The chromophores have a high thermal stability: the decomposition temperature is above 238 °C. For isomers with 1-methyl-2-phenylindolizin-3-yl (MPI-3) donor group higher values of β are predicted in comparison with those having 3-methyl-2-phenylindolizin-1-yl (MPI-1) donor group. This is in good agreement with the experimental and theoretical values of the HOMO-LUMO energy gap. Indolizine-based chromophores with barbituric acceptor and isophorone moieties in the π-bridge demonstrate the combination of good characteristics.

Analyses based on molecular modeling, bonds distribution, and subsequent quantum-chemical calculations of open-shell fullerenes C74 (D3h) and C76 (Td) as initial representatives of polymers have shown that the binding of molecules is most probable with participation of c–c atoms for fullerene C74 (D3h) and b–c and c–c atoms for fullerene C76 (Td). Open-shell triplet configurations of dimer molecules remains more favorable, including trimers, tetramers, and pentamers of C74 (D3h) having a chain structure. Analysis of the published experimental data demonstrates the reconcilable picture of this IPR C74 (D3h) radical fullerene “life”.

Membrane-electrode assemblies (MEA) with a cathode catalyst made of a nickel sodium pectate complex PG-NaNi with a 25% substitution of sodium for nickel, and with a commercial anode catalyst made of platinum black have been successfully created. Tests in a H2/O2 proton exchange membrane fuel cell (PEMFC) yielded the values of the maximum current density of 59 mA cm−2 and the maximum power density of 5.9 mW cm−2. These results permit the development of environmentally friendly and stable cathode catalysts for PEMFCs made of a readily available biological raw material, pectin.

By acid-catalyzed reaction of substituted isatins with Girard’s reagent T, new water-soluble isatin-3-acylhydrazones were obtained with high yields. Their antimicrobial activity was evaluated. Selective activity against Gram-positive bacteria (S. aureus 209p and B. cereus 8035) and yeast-like fungus Candida albicans 855–653 along with low hematoxicity was established.

To further explore the potential application of the indolizine donor group in nonlinear optical (NLO) chromophores, we have designed and synthesized new push-pull chromophores (MPI-1)-V-TCF and (MPI-3)-V-TCF, having isomeric 3(1)-methyl-2-phenylindolizin-1(3)-yl (MPI-1(3)) electron donor and TCF acceptor, and compared them with dimethyl aniline (DMA) analogues. The Uv-Vis (linear optical) properties and solvatochromic behavior were also investigated; theoretical predictions of molecular NLO characteristics were done on the basis of the DFT calculations. The indolizine-based chromophores have high thermal stability: the decomposition temperature is 348 °C for (MPI-1)-V-TCF and 343 °C for the (MPI-3)-V-TCF, which is by 10–15 °C higher than that for the chromophore DMA-V-TCF. An important role is played by the bulky phenyl group, which prevents the aggregation of chromophores in guest-host doped polymer films. In NLO activities, the doped (MPI-1)-V-TCF/PMMA and (MPI-3)-V-TCF/PMMA films display the NLO coefficient, d33, values of 40 and 42 pm/V, correspondingly, at the chromophore load of 20 wt%.

A complex of physicochemical methods was used to study the aggregation characteristics of an imidazolium-containing amphiphile and its ability for complex formation with bovine serum albumin (BSA). Tensiometry showed that adding BSA to the surfactant decreases the aggregation threshold of the system by a factor of 50. Dynamic light scattering established, that the size of the surfactant–BSA complexes depends on the size of the polypeptide (6–10 nm) and is independent on the concentrations of the surfactant and BSA. The Stern‒Volmer constants and surfactant‒protein binding constants were calculated from fluorescence spectroscopy data.

A method of synthesis of a new class of push-pull chromophores with vinylquinoxalinone conjugated bridges has been proposed; two isomeric pairs of chromophores with dimethyl aniline donor and dicyanovinyl or tricyanofuran acceptors linked via vinyl-7(6)-quinoxalinon-3-yl or vinyl-7(6)-quinoxalinone-3-vinyl bridges, correspondingly, have been synthesized and systematically investigated. The solvatochromic behavior, thermal stability and electrochemical properties were studied to establish the structure-property relationships. Chromophore 7-DMA-VQ on V-TCF exhibits the minimal HOMO-LUMO energy gap (ΔE 0.84 eV) and the highest thermal stability (T d = 313 °C).

Fabrication of multifunctioning systems using noncovalent self-assembly principles are of great importance in biomimetic drug and gene delivery systems construction. Herein, supramolecular systems based on homologous series of amphiphiles bearing imidazolium fragment (C n H 2n+1 Im + Br − , where n = 14, 16, 18) have been fabricated and studied. Their aggregation behavior, solubilization activity toward hydrophobic guest, interaction with DNA decamer as well as integration with lipid bilayer have been investigated. Elongation of hydrophobic fragment by two methylene groups results in 4-fold decrease of critical micelle concentration, however does not affect solubilization properties. Examination of capability of amphiphiles studied to interact with DNA decamer have revealed some unconventional features: size and charge characteristics of amphiphile/oligonucleotide complexes do not depend on the length of hydrophobic tail, but the latter affects the efficacy of component binding, which achieves 100% for all amphiphiles. Capability of amphiphiles studied to integrate with lipid bilayer strongly depends on the length of hydrophobic fragment: the lower homologue C 14 H 29 Im + Br − increases the permeability of lipid bilayer, while the higher homologues C 16 H 33 Im + Br − and C 18 H 37 Im + Br − , vice versa, stabilize it. Enhance of capability of the drug (indometacin) to penetrate through lipid bilayer has been shown in the presence of C 14 H 29 Im + Br − .

New polymer materials based on methacrylic copolymers with chromophore-containing dendritic fragments in the side chain have been obtained. The nonlinear optical coefficients of 22, 23 and 28 pm V–1 have been determined for polymers with 18, 21 and 30 mol% content of dendritic fragments, respectively.

Fifteen open-shell isomers off the forty six IPR isomers of fullerene C90 were found and investigated: 5 (Cs), 7 (C1), 9 (C1), 10 (Cs), 11 (C1), 20 (C1), 21 (C1), 22 (C1), 23 (C2), 24 (C1), 25 (C2v), 41 (C2), 42 (C2), 43 (C2), and 44 (C2). According to developed by us approach the positions of single, double, and delocalized π-bonds in the molecules of these isomers are shown for the first time. The obtained results of electronic and geometrical structures are fully supported by DFT method with the B3LYP functional at the 6–31G and 6–31G* levels. Molecules of these open-shell isomers contain different radical substructures (mainly the phenalenyl-radical substructures), they should be unstable and could not be obtained as empty molecules. Nevertheless, there is a possibility of obtaining them in polymeric forms or as endohedral or exohedral derivatives.

The purposeful change of crystallization conditions for rac-3-chloro-5-hydroxy-1-(4-methylbenzyl)-4-[(4-methylphenyl)sulfanyl]-1,5-dihydro-2H-pyrrol-2-one 1 leads to two different crystal modifications, namely, a racemic compound in the triclinic space group P with Z′ = 1 (α-1) and a partial solid solution based on a racemic compound in the monoclinic space group P21 with Z′ = 4 (β-1). The first modification, α-1, is characterized by a higher density of the molecular packing in the crystal, while the second one, β-1, by a stronger system of hydrogen bonds and the presence of positional and substitutional disorder simultaneously. The analysis of the crystal structure of modifications α and β allowed us to define some structural aspects of the partial solid solution formation. Namely, the tendency to build a stronger hydrogen bond system enables the solution of enantiomers of 1 to be formed in the crystalline phase, whereas the propensity of the molecules to adopt a more favorable transoid conformation limits the solubility of the minor enantiomer.

New stable water-soluble metal complexes of citrus pectin (sodium polygalacturonate, PG-Na) with biogenic microelements (Ca and Fe) that we synthesized were characterized by infrared spectroscopy, dynamic light scattering, and atomic force microscopy. The temperature dependence of the mass of PG-Na, PG-NaFe, and PG-NaFeCa samples was studied by simultaneous thermal analysis. Water was found to be the major component of the gas phase in the first stage of mass loss of PG-NaFe and PG-NaFeCa, while the second stage involves decarboxylation and decomposition. The stimulating action of PG-NaFe and PG-NaFeCa on hematopoiesis in outbred rats during growing period, manifested as more than 10% increase in the hemoglobin concentration, was demonstrated.

Novel D-π-A chromophores with quinoxaline/quinoxalinone core in the π-conjugated bridge and various bulky groups in the acceptor moiety have been synthesized and systematically investigated at molecular level by UV–Vis spectroscopy, DFT calculations, electrochemical and TGA-DSC methods as well as at materials level by the example of PMMA-based composite polymer materials doped with different chromophore contents using molecular modeling and SHG technique. Chromophores exhibit positive dioxane/chloroform solvatochromic shift of ca. 50 nm, high values of first hyperpolarizability and dipole moment, small energy gap and good thermal stability. Tolyl and cyclohexylphenyl substituents unlike phenyl can be treated as most effective isolating groups, preventing chromophore pronounced aggregation even at 30 wt% content. Femtosecond nonlinear optical (NLO) activity was studied for poled thin guest-host polymer films with various chromophore weight content. Film DBA-VQPhV-TCFPhCy(25 wt%)/PMMA with bulky cyclohexylphenyl groups in chromophore acceptor shows maximal NLO coefficient, d33, values among the studied materials (37 pm/V) as well as good long-term stability of NLO response together with excellent chromophore thermal stability (Td = 256 °C). Composite materials doped with quinoxaline chromophores are photostable with respect to laser pulses with peak intensities up to 11 GW/cm2.

Achieving high thermal stability and control of supramolecular organization of functional dyes in sensors and nonlinear optics remains a demanding task. This study was aimed at the evaluation of thermal behavior and Langmuir monolayer characteristics of topologically varied nitrothiacalixarene multichromophores and phenol monomers. A nitration/azo coupling alkylation synthetic route towards partially O-substituted nitrothiacalixarenes and 4-nitrophenylazo-thiacalixarenes was proposed and realized. Nuclear magnetic resonance (NMR) spectroscopy and X-ray diffractometry of disubstituted nitrothiacalix[4]arene revealed a rare 1,2-alternate conformation. A synchronous thermal analysis indicated higher decomposition temperatures of nitrothiacalixarene macrocycles as compared with monomers. Through surface pressure/potential-molecular area measurements, nitrothiacalixarenes were shown to form Langmuir monolayers at the air&ndash, water interface and, through atomic force microscopy (AFM) technique, Langmuir&ndash, Blodgett (LB) films on solid substrates. Reflection-absorption spectroscopy of monolayers and electronic absorption spectroscopy of LB films of nitrothiacalixarenes recorded a red-shifted band (290 nm) with a transition from chloroform, indicative of solvatochromism. Additionally, shoulder band at 360 nm was attributed to aggregation and supported by gas-phase density functional theory (DFT) calculations and dynamic light scattering (DLS) analysis in chloroform&ndash, methanol solvent in the case of monoalkylated calixarene 3. Excellent thermal stability and monolayer formation of nitrothiacalixarenes suggest their potential as functional dyes.

Two isomeric indolizine-based chromophores (MPI-1)-OT-TCF and (MPI-3)-OT-TCF with octatetraene π-bridge and tricyanofuran acceptor moieties have been synthesized and systematically investigated. Chromophores exist as a mixture of E- and Z-isomers in low-polar dioxane and chloroform solutions, while in polar solvents only one isomer is observed. The chromophores show excellent thermal stability with Td>260 °C (DSC) and small energy gap between the frontier orbitals (about 0.8–0.9 eV) established by DPV method. The chromophores exhibit absorption in the visible and near IR region. Solvatochromic shifts amounting to ca. 100 nm when passing from dioxane to DMSO solutions are accompanied by appearance of an additional narrow intensive absorption band at ca. 915–950 nm resulting from the cross of cyanine limit. For the first time electro-optic activity of composite materials doped by indolizine based chromophores have been investigated; EO coefficient of poled (MPI-3)-OT-TCF/PMMA film afforded value of 29 pm/V at 10 wt% load.

The analysis of previously experimentally obtained and characterized by X-ray perfluoralkyl derivatives C74(D3h)(CF3)12 and C76(Td)(CF3)12 have shown for the first time that the most feasible positions of addends are phenalenyl-radical substructures and/or hexagons with delocalized pi-bonds, that lead to stabilization of these molecules. The most probable addition positions of H• and CF3• radicals to the «missing» fullerenes С74 (D3h) and С76 (Td) are revealed on the basis of developed approach of molecular modeling followed by DFT calculations. Radical addition reactions seem to be useful for stabilization of open-shell fullerenes.