Irina V. Lijanova

The Inhibition of Aluminum Corrosion in Sulfuric Acid by Poly(1-vinyl-3-alkyl-imidazolium Hexafluorophosphate)

Compounds of poly(ionic liquid)s (PILs), derived from imidazole with different alkylic chain lengths located in the third position of the imidazolium ring (poly(1-vinyl-3-dodecyl-imidazolium) (PImC12), poly(1-vinyl-3-octylimidazolium) (PImC8) and poly(1-vinyl-3-butylimidazolium) (PImC4) hexafluorophosphate) were synthesized. These compounds were tested as corrosion inhibitors on aluminum alloy AA6061 in diluted sulfuric acid (0.1–1 M H2SO4) by weight loss tests, polarization resistance measurements and inductively coupled plasma optical emission spectroscopy. Langmuir’s isotherms suggested film formation on bare alloy while standard free energy indicated inhibition by a physisorption process. However, compound efficiencies as inhibitors ranked low (PImC12 > PImC8 > PImC4) to reach 61% for PImC12 in highly diluted acidic solution. Apparently, the high mobility of sulfates favored their adsorption in comparison to PILs. The surface film displayed general corrosion, and pitting occurred as a consequence of PILs’ partial inhibition along with a continuous dissolution of defective patchy film on formation. A slight improvement in efficiency was displayed by compounds having high molecular weight and a long alkyl chain, as a consequence of steric hindrance and PIL interactions.

Synthesis of 5-aryl-1,4-benzodiazepine derivatives attached in resorcinaren-PAMAM dendrimers and their anti-cancer activity.

A series of resorcinaren-PAMAM dendrimers with benzodiazepines in the periphery were synthesized and their anticancer properties studied. The synthesized dendrimers showed potential anticancer activities, which were enhanced in the presence of a chloro-substituent in the second ring of the 5-aryl-1,4-benzodiazepine. The dendrimers were characterized by IR, (1)H and (13)C NMR, UV-vis absorption, electrospray (ES) and/or MALDI-TOF mass spectrometries.

Dendrimers containing ferrocene and porphyrin moieties: synthesis and cubic non-linear optical behavior.

Dendrons with ferrocenyl ended groups joined by styryl moieties were attached to a porphyrin core. All the dendrons used for dendrimer synthesis showed trans configuration. The chemical structure of the first generation dendron was confirmed by X-ray crystallographic studies. The structure of the synthesized dendrimers was confirmed by 1H- and 13C-NMR, electrospray mass spectrometry and elemental analysis. Cubic non-linear optical behavior of the ferrocene and porphyrin-containing dendrimers was studied in solid thin films by THG Maker-Fringe technique at 1,260 nm.

Synthesis of porphyrin-dendrimers with a pyrene in the periphery and their cubic nonlinear optical properties.

Dendrons of pyrene derivatives were attached to a porphyrin core. A marked effect in solution for the dendrimers was observed in the absorption spectra. All the compounds obtained were characterized by 1H-, 13C-NMR, FTIR, UV-vis, MALDI-TOF or FAB+ mass spectrometry and elemental analysis. The cubic nonlinear optical behavior of some the synthesized compounds was tested via Z-Scan measurements in spin-coated film samples.

Synthesis of PAMAM dendrimers with a resorcinarene core and their metal complexation

Novel metal-chelating resorcinaren-poly(amidoamine) (PAMAM) dendrimers have been synthesised. The molecular structure of the resorcinaren-PAMAM dendrimers was characterised by 1H NMR, 13C NMR spectroscopy and by elemental analysis. The molecular weight of the dendrimers was confirmed by MALDI-TOF experiments. Gel permeation chromatography indicated that the product contained only one product. The metal-binding properties of the hyperbranched resorcinaren-PAMAM dendrimers were studied by means of the polymer-supported nanofiltration polymer-supported nanofiltration technique. The results show that the second generation resorcinaren-PAMAM dendrimers retained ∼80% of Cu(II) and ∼35% of Ni(II).

Double Molecular Antenna Pyrene - Bridge - Fullerene C60

C60 pyrene anthrylvinylene triads were synthesized with good yields by an O-alkylation reaction of pyrene an- thracene chloride derivatives and functionalized fullerene C60. The presence of lateral butoxy chains imparts good solubil- ity. The NMR data indicate the formation of only the trans isomers. After C60 cyclopropanation, the UV-Vis spectra show the pyrene electronic transition with an absorption band extending from 400 to 800 nm due to the combination of the  electronic transition of the antrylvinylene moiety and the C60 band, regardless the extension of the anthrylvinylene moiety. However, the emission is almost mirror-like with respect to the absorption bands of pyrene, suggesting that the HOMO and LUMO are more localized on this substituent. All the obtained compounds were characterized by 1 H and 13 C NMR,

New Synthesis, Structure and Analgesic Properties of Methyl 1-R-4-Methyl-2,2-Dioxo-1H-2λ6,1-Benzothiazine-3-Carboxylates

According to the principles of the methodology of bioisosteric replacements a series of methyl 1-R-4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylates has been obtained as potential analgesics. In addition, a fundamentally new strategy for the synthesis of compounds of this chemical class involving the introduction of N-alkyl substituent at the final stage in 2,1-benzothiazine nucleus already formed has been proposed. Using nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and X-ray diffraction analysis it has been proven that in the DMSO/K2CO3 system the reaction of methyl 4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylate and alkyl halides leads to formation of N-substituted derivatives with good yields regardless of the structure of the alkylating agent. The peculiarities of NMR (1Н and 13С) spectra of the compounds synthesized, their mass spectrometric behavior and the spatial structure are discussed. In N-benzyl derivative the ability to form a monosolvate with methanol has been found. According to the results of the pharmacological testing conducted on the model of the thermal tail-flick it has been determined that replacement of 4-ОН-group in methyl 1-R-4-hydroxy-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylates for the methyl group is actually bioisosteric since all methyl 1-R-4-methyl-2,2-dioxo-1H-2λ6,1-benzothiazine-3-carboxylates synthesized demonstrated a statistically significant analgesic effect. The majority of the substances can inhibit the thermal pain response much more effective than piroxicam in the same dose. Under the same conditions as an analgesic the N-methyl-substituted analog exceeds not only piroxicam, but more active meloxicam as well. Therefore, it deserves in-depth biological studies on other experimental models.

Synthesis and corrosion inhibition mechanism of ammonium-based ionic liquids on API 5L X60 steel in sulfuric acid solution

Abstract A novel class of four new-free-halide-ionic liquids (ILs) derived from ammonium was synthesized and characterized via spectroscopic methods such as 1H NMR and 13C NMR. The synthesized compounds were evaluated as corrosion inhibitors (CIs) of API 5L X60 steel in 1 M sulfuric acid by means of the potentiodynamic polarization and weight loss techniques. The results confirmed that the inhibition efficiency displayed by the four ILs is a function of their concentration and molecular structure. The obtained inhibition efficiency (η) ranged from 51 to 89%, confirming that the new class of ILs is good for corrosion inhibition purposes. The analysis of the potentiodynamic results showed that these compounds inhibit the corrosion of steel, classifying them as mixed-type CIs. The adsorption process of these new CIs on the API 5L X60 steel surface, which obeyed the Langmuir isotherm, was found to be physical and chemical. The SEM and EDX analyses confirmed the protection of steel in the corrosive medium.

Crystal structure of methyl 1-allyl-4-methyl-1H-benzo[c][1,2]thia­zine-3-carboxyl­ate 2,2-dioxide

In the title benzothiazine compound, the dihydrothiazine ring adopts a sofa-like conformation with the S atom displaced from the mean plane through the N and C ring atoms by 0.767 (1) Å. In the crystal, molecules are linked by C—H⋯π interactions, forming chains propagating along the a-axis direction.

Synthesis and Optical Properties of Double Antenna Pyrene-OPV- Fullerene C60

Two pyrene-OPV-Fullerene triads were synthesized by a Williamson alkylation of [6,6] diphenolmethanofullerene with chlorobenzyl-OPV-pyrene oligomers. Molecular structure of all compounds was characterized by 1H and 13C NMR, FTIR, UV-Vis, fluorescence spectroscopy, and confirmed by electron impact, electrospray or FAB+ mass spectrometry and elemental analysis. The optical properties in chloroform solution indicate that triads increase the molar absorptivity compared to methanophenylfullerene, revealing interesting light harvesting properties.