DMSO-d6 Solvent Research Articles

Reversibility in the Physical Properties of Agarose Gels following an Exchange in Solvent and Non-Solvent.

Agarose forms a homogeneous thermoreversible gel in an aqueous solvent above a critical polymer concentration. Contrary to the prevailing consensus, recent confirmations indicate that agarose gels are also stable in non-solvents like acetone and ethanol. A previous study compared gel characterisations and behaviours in water and ethanol, discussing the gelation mechanism. In the current work, the ethanol gel is exchanged with water to explore the potential reversibility of the displacement of water in agarose. Initially, the structure is characterised using 1H NMR in DMSO-d6 and D2O solvents. Subsequently, a very low yield (0.04) of methyl substitution per agarobiose unit is determined. The different gels after stabilisation are characterised using rheology, and their physical properties are compared based on the solvent used. The bound water molecules, acting as plasticizers in aqueous medium, are likely removed during the exchange process with ethanol, resulting in a stronger and more fragile gel. Next, the gel obtained after the second exchange from ethanol back to water is compared with the initial gel prepared in water. This is the first time where such gel has been characterised without undergoing a phase transition when switching from a good solvent to a non-solvent, and vice versa, thereby testing the reversibility of the solvent exchange. Reversibility of this behaviour is demonstrated through swelling and rheology experiments. This study extends the application of agarose in chromatography and electrophoresis.

Synthesis and characterization A derivative of levofloxacin and a study of its bacteriostatic activity

This study includes two newly synthesized prodrugs of Levofloxacin derivatives mono and dipeptide H2, where was the Synthesized monoPeptide as Levofloxacin-Histadine (L-H), as well as dipeptide H6 as Synthesis of diPeptide (phenylalanine- levofloxacin (GPA-L), using a Levofloxacin substituted. Spectroscopic data were studied for two derivative compounds H2 and H6 and reactivity indices were characterized using techniques FT-IR, 1H-NMR, and 13C-NMR. All the newly produced derivative compounds H2 and H6 have FT-IR spectra that share similarities in certain fingerprint-like bands and other bands. The essential functional group vibration bands. In the DMSO-d6 solvent, the compound H2, and H6 of 1H NMR spectra were studied, Typically, the fitted intensity ratio of the observed compound 1H NMR spectra gives, and the expected signals. The DMSO-d6 solvent was employed to record the 13C NMR spectra of levofloxacin derivatives H2 and H6. portrayed the 13C NMR spectra of generated compounds H1 through H6, comprised of the 13C NMR data. where done Further confirmation of the properties of the developed molecule emerged from 13C-NMR spectra. 1
 The bioactivity was studied for two derivative compounds H2 and H6 against three gram-positive and three gram-negative Bacteria. The mono and dipeptide prodrugs that are derivatives of levofloxacin have appeared to have excellent results against these Bacteria. Antibiotic susceptibility experimental findings revealed that various bacteria had taken different approaches to the tested drugs. most bacteria isolated in gram-positive and gram-negative demonstrated severe sensitivity to the generated compounds (H2 and H6). The spectral results in the FT-IR analyses as well as the nuclear magnetic resonance studies showed the high validity of the compounds formed ( H2 and H6) interaction, as well as the biological results showed a clear positive in killing bacteria of the type of Gram-negative and Gram-Positive.

Monohalogenated methyl- and methoxy-benzoic acids: A combined experimental and quantum chemical theoretical study on their structure, vibrational analysis and molecular parameters

In this paper, the molecules 3-fluoro-2-methylbenzoic acid; 3-chloro-2-methoxybenzoic acid; and 3-bromo-2-methylbenzoic were investigated using experimental and quantum chemical theoretical approach for vibrational and electronic properties from the optimized structure. Becke three parameter Lee–Yang–Parr density functionals along with 6-311++G(d,p) basis set were employed to compute their geometric optimization, fundamental frequencies and molecular parameters. The detected FT-IR and FT-Raman spectra were compared with their simulated spectra and the rms error between the detected and simulated vibrational frequencies was found at 6.17, 7.22 and 6.76 cm−1 for FMA, CMA and BMA, respectively. All the vibrational fundamentals were assigned unequivocally using potential energy distribution (PED) obtained in the computations. 1H and 13C NMR chemical shifts were evaluated by integrating the gauge-independent atomic orbital (GIAO) method with DFT and compared with corresponding experimental values. TD-DFT approach was followed to compare the simulated absorption maxima (λmax) in DMSO-d6 solvent with observed values and interpreted in terms of HOMO and LUMO. The global reactive descriptors were estimated from the associated energies of HOMO and LUMO which describe the reactivity and stability of the molecules. Molecular electrostatic potential (MEP) surface has been determined using the charge density distributions to demonstrate electrophilic and nucleophilic nature of the molecules. DFT computations also ascertained the applicability of the titled molecules as NLO materials from the computed values of dipole moment and hyperpolarizability. Thermodynamic parameters and rotational constants were also evaluated employing rigid rotor harmonic oscillator approximation. Natural bond orbital (NBO) analysis confirmed the charge delocalization due to intra-molecular interactions.

Characterization of Agarose Gels in Solvent and Non-Solvent Media.

Agarose is known to form a homogeneous thermoreversible gel in an aqueous medium over a critical polymer concentration. The solid-liquid phase transitions are thermoreversible but depend on the molecular structure of the agarose sample tested. The literature has mentioned that agarose gels could remain stable in non-solvents such as acetone or ethanol. However, there has been no characterization of their behavior nor a comparison with the gels formed in a good solvent such as water. In the first step of this article, the structure was characterized using 1H and 13C NMR in both D2O and DMSO-d6 solvents. DMSO is a solvent that dissolves agarose regardless of the temperature. First, we have determined a low yield of methyl substitution on the D-galactose unit. Then, the evolution of the 1H NMR spectrum was monitored as a function of temperature during both increasing and decreasing temperature processes, ranging from 25 to 80 °C. A large thermal hysteresis was obtained and discussed, which aided in the interpretation of rheological behavior. The hysteresis of NMR signals is related to the mobility of the agarose chains, which follows the sol/gel transition depending on the chains' association with H-bonds between water and the -OH groups of agarose for tightly bound water and agarose/agarose in chain packing. In the second step of the study, the water in the agarose gel was exchanged with ethanol, which is a non-solvent for agarose. The resulting gel was stable, and its properties were characterized using rheology and compared to its behavior in aqueous media. The bound water molecules that act as plasticizers were likely removed during the exchange process, resulting in a stronger and more brittle gel in ethanol, with higher thermal stability compared to the aqueous gel. It is the first time that such gel is characterized without phase transition when passing from a good solvent to a non-solvent. This extends the domains of application of agarose.

Quantum Chemical Study for Structure, Electronic and NLO Properties of 2-Amino-4-nitrotoluene and 2-Amino-5-nitrotoluene

Molecular structure, molecular orbital energies; and global reactivity parameters of 2-amino-4-nitrotoluene (2A4NT) and 2-amino-5-nitrotoluene (2A5NT) were studied using DFT/B3LYP/6-311++G(d,p) level of theory. The energy difference between HOMO and LUMO was found to be 3.35 eV and 3.41 eV, respectively. Computed electrophilicity index values (ω = 12.63 and 14.61) demonstrate that the molecules are strong electrophile. The reactive sites and charge distribution of the compounds were analyzed by MEP surface. The non-linear optical activity of title compounds was studied by calculating the values of total dipole moment and mean first order hyperpolarizability. The natural charges of the molecules were obtained from NBO analysis; and the entire atomic charges were acquired by means of Mulliken study. The NMR (13C & 1H) theoretical chemical shifts were predicted by using GIAO approach in DMSO-d6 solvent. The values of energy, oscillator strength and absorption wavelength were computed from the UV-Vis spectra using TD-DFT method.

N-Acetyl Side-Chain Conformation in Saccharides: Solution Models Obtained from MA'AT Analysis.

MA'AT analysis has been applied to model the conformational properties of N-acetyl side-chains in biologically important GlcNAc and ManNAc monosaccharides and in a βGlcNAc-(1→4)-βGlcNAc disaccharide. Density functional theory calculations were conducted to obtain parameterized equations that relate the magnitudes and signs of 10 spin-coupling constants to conformations of the C2-N2 bonds of GlcNAc and ManNAc. Six of these equations were used with experimental J-couplings, measured in H2O/2H2O and DMSO-d6 solvents in selectively 13C-labeled compounds, to model the C1-C2-N2-C1' torsion angle (θ1) in GlcNAc and ManNAc residues. MA'AT analysis gave mean values of θ1 of 106° for αGlcNAc and ∼116° for βGlcNAc residues, with circular standard deviations (CSDs) of 21-22° in aqueous solution, in excellent agreement with those obtained by aqueous molecular dynamics (MD) simulation. Parameter space plots revealed unique MA'AT fits of the data, and root mean squared deviations (<0.2 Hz) were twofold smaller than those back-calculated from MD models, indicating that the MA'AT models better fit the experimental J-couplings. Context effects on both θ1 values were found to be small in a βGlcNAc-(1→4)-βGlcNAc disaccharide. MA'AT analysis gave a mean value of θ1 of 249° for αManNAc in H2O/2H2O, with a CSD of ∼19°, with both values in good agreement with MD. MA'AT models of N-acetyl side-chains are similar to those obtained previously for O-acetyl side-chains (J. Phys. Chem. B 2017, 121, 66-77). Both O- and N-acetylation conformationally constrain the C-O or C-N bonds relative to the same bonds in unsubstituted compounds. The present work confirms the ability of MA'AT analysis to reveal relatively small changes in mean molecular torsion angles in solution and provides additional evidence of the method as an experimental tool complementary to MD simulation.

Identification and Quantification by NMR Spectroscopy of the 22R and 22S Epimers in Budesonide Pharmaceutical Forms

The authors developed four variants of the qNMR technique (1H or 13C nucleus, DMSO-d6 or CDCl3 solvent) for identification and quantification by NMR of 22R and 22S epimers in budesonide active pharmaceutical ingredient and budesonide drugs (sprays, capsules, tablets). The choice of the qNMR technique version depends on the drug excipients. The correlation of 1H and 13C spectra signals to molecules of different budesonide epimers was carried out on the basis of a comprehensive analysis of experimental spectral NMR data (1H-1H gCOSY, 1H-13C gHSQC, 1H-13C gHMBC, 1H-1H ROESY). This technique makes it possible to identify budesonide epimers and determine their weight ratio directly, without constructing a calibration curve and using any standards. The results of measuring the 22S epimer content by qNMR are comparable with the results of measurements using the reference HPLC method.

Development of Genistein Synthesis for Use as a Certified Reference Material

Introduction. The use of certified reference materials (CRMs) ensures metrological traceability and comparability of analysis results performed in different laboratories, by different analysts, at different times. Genistein is a promising substance with a wide spectrum of pharmacological action. genistein is widely used in dietary supplements. Development of regulatory documents for CRM of genistein will ensure the quality of drugs and dietary supplements.Aim. Aim of our study is to improve of the ways of synthesis and determination of spectrum characteristics of genistein for the certification of CRM.Materials and methods. We used synthetic genistein, (Ph.D. V. Yu. Kovtun SPC "Pharmzashchita") (sample № 1) and genistein synthesized and studied at the departments of pharmaceutical chemistry and chemical technology of medicinal substances SPCPU (sample № 2). Infrared spectra of genistein samples were collected on an FSM 1201 infrared Fourier spectrometer (OOO Infraspek, Russia) via KBr pellets technique. All the spectra were collected in the 4000–500 cm−1 range. The NMR (1H and 13C) measurements were performed with a BrukerAvance III NMR spectrometer (400 and 100 MHz) (Bruker, Germany) in DMSO-d6 solvent. Raman spectra were recorded by an ORTES-785TRS-2700 analytical Raman scattering system at a laser power of 100 mW (OPTEC JSC, Russia). Laser interaction time was 5, 10, 20 and 60 seconds. The results were processed using the software "BWSpec 4.10_4", USA. GC-MS was performed on an Agilent Technologies 7890A gas chromatograph (Agilent Technologies, USA) with a 7693 autoinjector and a Hewlett Packard 5975C mass selective detector.Results and discussion. The synthesis was carried out according to the developer's method. The stage "removal of the alkyl protection" has been improved. The spectra of the synthesis intermediate of genistein (biochanin A) correspond to the literature data. Samples of genistein were investigated by methods: MC and NMR 13С, 1Н. The structure of the investigated substance was confirmed; Raman and IR spectroscopy showed that the spectra of the samples do not differ from each other and there are no additional signals.Conclusion. The spectrum characteristics of samples of genistein were obtained by NMR, IR and Raman spectroscopy, which will be used in the regulatory documentation for CRM of genistein. All of this will make it possible to control the quality of medicines based on it and to identify substandard dietary supplements.

Study on the Chemical Structures and Free Radical Scavenging Ability of Anthraquinones and Its c-Glycosides from Rumexjaponicus Houtt.

Rumex japonicus Houtt. (RJH) is a kind of Traditional Chinese Medicine (TCM) widely used in the treatment of serious skin diseases such as psoriasis. To further explore its bioactive components, the five-year root of RJH was used, the nuclear magnetic resonance (NMR) technique was employed with DMSO-d6 solvent for chemical structures, the scavenging capacity of the free radicals (DPPH, alkyl, –OH, and ˙O−2) was evaluated by electron spin resonance (ESR) method. In the results, seven compounds that were wholly characterized as anthraquinones (1 and 2), its c-glycosides (4–7), and flavonoid glycoside (3) especially for the hydrogen atoms from –OH groups located at phenol rings and glucose moieties. The compound 4 and 5 showed the significant bioac-tivity with the IC50 values (DPPH: 23.34 and 23.25 μM; alkyl: 20.27 and 20.15 μM; –OH: 26.03 and 25.50 μM; and ˙O−2: 14.69 and 14.68 μM, respectively). In conclusion, the DMSO-d6 solvent could make active protons be expressed clearly for accurate assignments. The compounds 4 and 5 could be suggested to be applied for potential candidates for related drugs.

Synthesis and evaluation of molecular structure from torsional scans, study of molecular characteristics using spectroscopic and DFT methods of some thiosemicarbazones, and investigation of their anticancer activity

Synthesis of 2-((2-aminopyridin-3-yl) methylene) hydrazinecarbothioamide (APHT) was attempted. Elemental analysis and NMR spectra were used to ascertain its formation. Torsional potential energy scans for all five of its rotating bonds were made to get approximate dihedral angles. UV–Vis spectra were measured for APHT and 2-((2-aminopyridin-3-yl) methylene)-N-methylhydrazinecarbothioamide (APMHT). Their anticancer activity was determined experimentally, for human carcinoma cell lines pertaining to liver, colorectal, and lung. For both APHT and APMHT, frontier molecular orbital parameters, NLO behaviour, and NBO characteristics were determined using DFT/B3LYP/6-311++G(d,p) level of theory. TD-DFT was used to compute absorption maxima (λmax) of electronic transitions for both molecules in DMSO-d6 solvent. Frontier molecular orbitals were used to understand origin of UV–Vis spectra and chemical reactivity of the two molecules. Good agreement was found between measured and computed structure parameters. This is also true of experimental and theoretical UV–Vis spectra. The computations demonstrated that both the molecules were good for NLO applications, which was substantiated by NBO analysis. Existence of bifurcated intramolecular hydrogen bond was predicted for both APHT and APMHT.

Conformations, structure, vibrations, chemical shift and reactivity properties of isoquinoline–1–carboxylic acid and isoquinoline–3–carboxylic acid – Comparative investigations by experimental and theoretical techniques

The most stable conformer of isoquinoline–1–carboxylic acid (IQ1CA) and isoquinoline–3–carboxylic acid (IQ3CA) are determined and the geometry has been optimised with B3LYP method using high level 6–311++G** and cc–pVTZ basis sets. The structure, electronic properties, vibrational fundamental modes, thermodynamic properties and chemical shifts of the compounds are investigated. The vibrational fundamental modes are assigned and analysed by utilising FT–IR and FT–Raman spectrum of the compounds recorded in the range of 4000–400 and 4000–100 cm−1, respectively. The LUMO–HOMO energy difference is determined to explain the charge transfer within the molecule. The molecular electrostatic potential and total electron density of the molecules are determined to explain the size, shape and the reactive sites (polar) of the molecules. The 1H and 13C NMR chemical shifts of the compounds are determined by Gauge Invariant Atomic Orbital (GIAO) method using DMSO–d6 solvent by B3LYP/cc–pVTZ method. The local and global chemical reactivity properties of the compounds have been investigated with the help of global and local reactivity descriptors.

Annular Tautomerism of 3(5)-Disubstituted-1H-pyrazoles with Ester and Amide Groups.

A series of disubstituted 1H-pyrazoles with methyl (1), amino (2), and nitro (3) groups, as well as ester (a) or amide (b) groups in positions 3 and 5 was synthesized, and annular tautomerism was investigated using X-ray, theoretical calculations, NMR, and FT-IR methods. The X-ray experiment in the crystal state showed for the compounds with methyl (1a, 1b) and amino (2b) groups the tautomer with ester or amide groups at position 3 (tautomer 3), but for those with a nitro group (3b, 4), tautomer 5. Similar results were obtained in solution by NMR NOE experiments in CDCl3, DMSO-d6, and CD3OD solvents. However, tautomer equilibrium was observed for 2b in DMSO. The FT-IR spectra in chloroform and acetonitrile showed equilibria, which can be ascribed to conformational changes of the cis/trans arrangement of the ester/amide group and pyrazole ring. Theoretical analysis using the M06-2X/6-311++G(d,p) method (in vacuo, chloroform, acetonitrile, and water) and measurement of aromaticity (NICS) showed dependence on internal hydrogen bonds, the influence of the environment, and the effect of the substituent. These factors, pyrazole aromaticity and intra- and inter-molecular interactions, seem to have a considerable influence on the choice of tautomer.

Catalytic α-Selective Deuteration of Styrene Derivatives.

We report an operationally simple protocol for the catalytic α-deuteration of styrenes. This process proceeds via the base-catalyzed reversible addition of methanol to styrenes in DMSO -d6 solvent. The concentration of methanol is shown to be critical for high yields and selectivities over multiple competing side reactions. The synthetic utility of α-deuterated styrenes for accessing deuterium-labeled chiral benzylic stereocenters is demonstrated.

Pretreatment of anaerobic digester samples by hydrochloric acid for solution-state 1H and 13C NMR spectroscopic characterization of organic matter

Pretreatment of anaerobic digester samples by hydrochloric acid (HCl) resulted in removal of Fe-based mineral and coordination compounds, attenuating their interferences with solution-state nuclear magnetic resonance (NMR) spectroscopic characterization of the solid phase organic matter. Substrate (influent) and digestate (effluent) samples from two full-scale anaerobic digesters, designated CD (co-digester) and SSD (sewage sludge digester), were investigated. Pretreatment of CD samples with 0.2–2.0 mol l−1 HCl and pretreatment of SSD samples with 1.0–3.0 mol l−1 HCl removed 96–100% and 76–80% of total Fe, respectively. Pretreatment declined overall paramagnetic characteristics of digestate samples, manifested by 50% (CD) and 70% (SSD) decrease in electron paramagnetic resonance signal intensities. As a result, meaningful solution-state 1H,13C heteronuclear single quantum coherence and 1H NMR spectra of DMSO-d6 soluble organic matter could be acquired. Sample pretreatment with the lowest concentration of HCl resulted in alteration of C:N ratios in solid phase, likely due to removal of labile organic and inorganic C- and N-containing compounds, while elevating the HCl concentration did not further change the C:N ratios. Furthermore, sample pretreatment increased the solubility of carbohydrates and proteins in DMSO-d6, enabling the detection of NMR resonances from certain structural units of carbohydrates (e.g. anomeric O2CH) and proteins (e.g. CHα in amino acids). Both attenuation of the paramagnetic matrix as well as an enhanced solubility of carbohydrate and protein fractions of the samples in DMSO-d6 solvent contributed to an improved molecular characterization of anaerobic digester samples by solution-state NMR analysis.

Identification of Terpene Lactones and Flavonol Glycosides in Preparations Based on Ginkgo Biloba Extract and a New Way of Semi-Quantitative Determination of Flavonol Glycosides by 1H NMR Spectroscopy

The composition of terpen lactones and flavonol glycosides of commercial preparation series based on Ginkgo biloba extracts was investigated by 1H NMR spectroscopy. The content of individual terpen lactones was determined using DMSO-d6 and acetone-d6 solvents. The effect of the structure of flavonol glycosides on the signal of the hydroxyl proton at a position 5 of the ring A was examined. A new approach was proposed for semiquantitative determination of the total amount of flavonol glycosides by the integral intensity of this signal, which is a superposition of the singlets in the region of 12.5–12.65 ppm of individual flavonoids in DMSO-d6. Since the corresponding signals of aglycones (quercetin, kaempferol, isorhamnetin), which are minor components of the Ginkgo biloba extracts, appear separately in a slightly different region (12.45–12.48 ppm), the proposed method can also be used for detecting adulteration of Ginkgo biloba extracts by means of the addition into them of relatively cheap aglycones or rutin as well as for assessment of the content of flavonoids of similar structure in some types of plant raw materials.

СИНТЕЗ ТА АНТИМІКРОБНІ ВЛАСТИВОСТІ 5-(4-R-БЕНЗИЛ)-2-ТІАЗОЛІЛАМІДІВ 5-АРИЛІДЕНРОДАНІН-3-АЛКАНКАРБОНОВИХ КИСЛОТ

Мета роботи. Синтез N-[5-(4-R-бензил)тіазол-2-іл]-2-[5-(4-R1-бензиліден)-4-оксо-2-тіоксотіазолідин-3-іл]ацет- та пропіонамідів із наступним дослідженням їх антимікробної активності.Матеріали і методи. При виконанні експериментальної частини роботи використано традиційні методи органічного синтезу. Вихідні реагенти синтезовані за відомими методиками із комерційно доступних реактивів. Спектри ЯМР одержаних сполук знімали на приладі Varian VXR-400, розчинник DMSO-d6, стандарт – тетраметилсилан. Антимікробну активність отриманих сполук вивчали за допомогою мікрометоду з використанням одноразових 96-лункових стерильних полістиролових планшетів та мікротитраторів Такачі.Результати й обговорення. Взаємодією 5-(4-R-бензил)-1,3-тіазол-2-амінів 1а-с з хлорангідридами (5-R1-бензиліден-4-оксо-2-тіоксотіазолідин-3-іл)оцтових 2а-с та пропіонових 3а-с кислот отримано ряд нових амідів 9a-і та 10a-і. Досліджено їх антимікробну активність. Встановлено, що сполуки 9a та 10h проявляють високу активність по відношенню до S.aureus ATCC № 25923.Висновки. Вперше отримано низку N-[5-(4-R-бензил)тіазол-2-іл]-2-[5-(4-R1-бензиліден)-4-оксо-2-тіоксотіазолідин-3-іл]ацет- 9a-і і пропіонамідів 10a-і та досліджено in vitro їх антимікробну активність. Знайдено сполуки, що володіють високою активністю по відношенню до S.aureus ATCC № 25923.

A Bis(Boronic Ester)-Based Fluorogenic and Chromogenic Sensor for F-and Cu2+

In this work, we designed a new boronic ester based ditopic Schiff's base receptor, 2,2′-(((1E,1′E)-((2,4,8,10-tetraoxa-3,9-diboraspiro[5.5]undecane-3,9-diyl)bis(4,1-phenylene)) bis(me-thanylylidene))bis(azanylylidene))diphenol (H2L)by condensing ortho-aminophenol, 4-formyl phenyl boronic acid and pentaerythritol. The receptor has been thoroughly characterized by 1H, 13C, 11B NMR spectroscopy as well as high resolution mass spectroscopy and by elemental analyses. Hydrolytic stability of the receptor was also checked by recording its 1H NMR spectrum in mixed DMSO-d6 and D2O solvent. The receptor acts as highly selective and sensitive probe for the detection of Cu2+ and F– among the studied ions in solution. Both anion and cation sensing studies were thoroughly investigated through multiple optical channels such as UV-vis absorption and steady state and time-resolved emission spectroscopic techniques. Among the studied anions, only F– induces color and absorption and emission and time-resolved emission spectral changes in dimethylsulphoxide.Addition of Cu2+ ion to the solution of the receptor in dimethylsulfoxide-water (5:2 v/v) leads to remarkable color and absorption spectral changes. Association constants of the receptor towards F– have been also evaluated from the absorption/emission titration data.

Solvent–Solid Interface of Acid Catalysts Studied by High Resolution MAS NMR

High-resolution magic angle spinning (HR-MAS) NMR spectroscopy was used to study the effect of mixed solvent systems on the acidity at the solid–liquid interface of solid acid catalysts. A method was developed that can exploit benefits of both solution and solid-state NMR (SSNMR) by wetting porous solids with small volumes of liquids (<2 μL/mg) to create an interfacial liquid that exhibits unique motional dynamics intermediate to an isotropic liquid and a rigid solid. Results from these experiments provide information about the influence of the solvent mixtures on the acidic properties at a solid–liquid interface. Importantly, use of MAS led to spectra with full resolution between water in an acidic environment and that of bulk water. Using mixed solvent systems, the chemical shift of water was used to compare the relative acidity as a function of the hydration level of the DMSO-d6 solvent. Nonlinear increasing acidity was observed as the DMSO-d6 became more anhydrous. 1H HR-MAS NMR experiments on a varie...

СИНТЕЗ ТА ПРОТИПУХЛИННА АКТИВНІСТЬ 6-(Н/Ме)-N-(5-R-БЕНЗИЛ-1,3-ТІАЗОЛ-2-ІЛ)-4,5,6,7-ТЕТРАГІДРО-1- БЕНЗОТІОФЕН-3-КАРБОКСАМІДІВ

Мета роботи. Синтез нових 6-(Н/Ме)-N-(5-R-бензил-1,3-тіазол-2-іл)-4,5,6,7-тетрагідро-1-бензотіофен-3-карбокса-амідів та дослідження їх протипухлинної активності.Матеріали і методи. При виконанні експериментальної частини роботи використано традиційні методи органічного синтезу. Вихідні реагенти синтезовані за відомими методиками із комерційно доступних реактивів. Спектри ЯМР одержаних сполук знімали на приладі Varian VXR-400, розчинник DMSO-d6, стандарт – тетраметилсилан. Вивчення протипухлинної активності синтезованих сполук виконували в рамках міжнародної наукової програми DTP (Developmental Therapeutic Program) Національного інституту раку (NCI, Бетезда, Меріленд, США).Результати й обговорення. Отримано серію нових 6-(Н/Ме)-N-(5-R-бензил-1,3-тіазол-2-іл)-4,5,6,7-тетрагідро-1-бензотіофен-3-карбоксамідів (5а-h). Досліджено протипухлинну активність N-[5-(3-хлоробензил)-1,3-тіазол-2-іл]-4,5,6,7-тетрагідро-1-бензотіофен-3-карбоксаміду (5b), N-(5-бензил-1,3-тіазол-2-іл-6-метил-4,5,6,7-тетрагідро-1-бензотіофен-3-карбоксаміду (5d) та 6-мeтил-N-{5-[2-хлоро-5-(трифторометил)бензил]-1,3-тіазол-2-іл}-4,5,6,7-тетрагідро-1-бензотіофен-3-карбоксаміду (5h). Встановлено, що сполуки 5b і 5d володіють значним протипухлинним ефектом.Висновки. Вперше отримано серію нових 6-(Н/Ме)-N-(5-R-бензил-1,3-тіазол-2-іл)-4,5,6,7-тетрагідро-1-бензотіофен-3-карбоксамідів (5а-h). Досліджено їх протипухлинну активність. Ідентифіковано сполуки-хіти, перспективні для подальшої оптимізації.

Synthesis, crystal structures, and optical properties of the π-π interacting pyrrolo[2,3-b]quinoxaline derivatives containing 2-thienyl substituent

Three (E/Z)-diastereoisomers, based on pyrrolo[2,3-b]quinoxaline system as fluorophore and containing: 2-thienylmethyl (1), bis(2-thienylmethyl)-2-aminoethyl (3a), bis(2-thienylmethyl)-3-aminopropyl (3b) groups as substituents, were synthesized and characterized by X-ray structural analysis, PXRD, NMR, UV–Vis as well as fluorescence. These compounds are non-fluorescent in acetonitrile solution, however, they exhibit aggregation induced emission enhancement (AIEE) upon water addition and in solid state. X-ray structural analysis revealed that molecules with 2-thienylmethyl and bis(2-thienylmethyl)-2-aminoethyl groups form dimers and π-stacks through π-π interactions between anitiparallel oriented pyrroloquinoxaline cores with interplanar distances 3.45 Å and 3.20 Å, respectively. Conformation of bis(2-thienylmethyl)-3-aminopropyl group is imposed by incorporated DMSO-d6 solvent molecule and weak intermolecular S-π and CH-π interactions, that prevents π-π interaction between fluorophore cores. The correlation between crystal structure and fluorescent properties of synthesized molecules was discussed. The DFT calculations were performed to rationalize the differences between considered systems.