CH2 Protons Research Articles

Characterization of Bacillus pacificus KUMBNGBT-39-Derived Polyhydroxybutyrate and Impact of Physicochemical Factors on its Production.

The extensive use of various chemicals in synthetic plastics is toxic and threatens the biosphere. To address this, the study aimed to isolate, screen, characterize, optimize, and quantify polyhydroxybutyrate (PHB)-producing bacteria using cost-effective residues. Isolated from a landfill site, the Gram-positive, rod-shaped, spore-forming, motile bacterium with intracellular PHB granules was identified as Bacillus pacificus based on phenotypic and genotypic characteristics. Optimal PHB production parameters included a nutrient broth medium, 72h of incubation, a temperature of 37° C, a pH of 7.0, glucose as the carbon source, ammonium chloride as the nitrogen source, and a carbon-to-nitrogen ratio of 4:1, resulting in a 1.42-fold PHB production increase. B. pacificus was also cultured on various low-cost substrates. Among the oil wastes, feedstock showed the highest PHB production (1.983 ± 0.005g/L) and among agricultural residues, the maximum PHB was obtained from rice bran (1.626 ± 0.01g/L). UV-visible spectrophotometric, FT-IR, and HR-LCMS analysis of extracted PHB confirmed characteristics of PHB molecules (ʎ-max at 210nm, functional groups between 1152 and 2925cm-1). The 1H NMR analysis revealed distinct signals for protons resonating at aliphatic CH3 proton groups, bridged CH protons, and shielding CH2 proton regions that matched PHBs. Thermal gravimetric analysis (TGA) and direct scanning colorimetric (DSC) analysis revealed 89.4% degradation and melting temperature at 124.1°C for the extracted PHB compound.

Exploring the versatility of sulfur-containing heterocyclic metal complexes: Application in medical and prospects of visible-light-driven photocatalysis

Numerous heterocyclic moieties serve as the foundational structure for clinically employed drugs, underscoring the significance of heterocycles in the innovation of pharmacologically active compounds. In the present investigation, a heterocyclic skeleton of thiophene-clubbed benzimidazole (tmb) was developed and utilized to synthesize seven novel series of metal (M(II) = Co, Ni, Cu, and Zn) complexes to explore diverse applications including pharmacological and photocatalytic performance. A sharp singlet peak appeared at 5.72 ppm (tmb) and 5.94 ppm for the Zn(II)-tmb complex corresponding to -CH2 protons, as evidenced by 1H NMR results, confirming the formation of targeted compounds. Antimicrobial assay and docking studies confirmed that the mixed metal complex; [Cu(tmb)2(1,10-phen)Cl2] possesses the highest activity and displayed significant biofilm inhibition, achieving 86.35 and 89.8% at concentrations of 1 and 0.020 mg/mL, respectively against E. coli. Furthermore, the photocatalytic activity was monitored by the degradation of methylene blue dye under direct sunlight and [Cu(tmb)2Cl2] exhibited a maximum degradation efficiency of 96.15% in 45 min. These findings could serve as inspiration for the development of benzimidazole-based metal complexes as effective anti-biofilm and photocatalytic agents.

Inclusion complex of ionic liquid 1-dodecylpyridinium tetrafluoroborate with sulfobutyl ether-β-cyclodextrin: Preparation and characterization

In this article an inclusion complex of hydrophobic ionic liquid 1-dodecylpyridinium tetrafluoroborate (PyrC12-BF4) and sodium salt of sulfobutyl ether β-cyclodextrin (SB-β-CD) has been synthesized and studied using NMR spectroscopy, UV–Vis spectroscopy, FT-IR, TGA, DSC and XRD. The results of 1H NMR study revealed physicochemical interactions between the hydrophobic alkyl chain of PyrC12-BF4 and protons of the inner cavity of SB-β-CD, as well as between the CH protons of pyridinium cation and the polar SB-β-CD groups. The formation of an inclusion complex has also been revealed by Wilhelmy plate method. The binding constant of the SB-β-CD/PyrC12-BF4 complex determined by the method of Higuchi and Connors was found to be 1210 M–1. According to DSC analysis data, only one endothermic peak is observed in the thermogram of the SB-β-CD/PyrC12-BF4 inclusion complex, thus confirming the formation of a new supramolecular system. Additional characterization methods such as thermal mass spectroscopy and TEM were also applied for characterization of the synthesized complex. Complexation of long-chain pyridinium salt with SB-β-CD can be an efficient approach for the preparation of new antimicrobial formulations with reduced toxicity.

The effects of residual dipolar coupling on carnosine in proton muscle spectra.

Carnosine, an MR-visible dipeptide in human muscle, is well characterized by two peaks at ~8 and ~7 ppm from C2 and C4 imidazole protons. Like creatine and other metabolites, carnosine is subject to residual dipolar coupling in the anisotropic environment of muscle fibers, but the effects have not been studied extensively. Single-voxel TE 30-32 PRESS spectra from three different 3T studies were acquired from gastrocnemius medialis and soleus muscles in the human lower leg. In these studies, carnosine T2 values were measured, and spectra were obtained at three different foot angles. LCModel was used to fit the carnosine peaks with a basis set that was generated using shaped RF pulses and included a range of dipolar couplings affecting the C4 peak. A seven-parameter analytic expression was used to fit the CH2 doublets of creatine. It incorporated an optimized "effective TE" value to model the effect of shaped RF pulses. The fits confirm that the triplet C4 peak of carnosine is dipolar coupled to a pair of CH2 protons, with no need to include a contribution from a separate pool of freely rotating uncoupled carnosine. Moreover, the couplings experienced by carnosine C4 protons and creatine CH2 protons are strongly correlated (R2 = 0.88, P<0.001), exhibiting a similar 3cos2 θ - 1 dependence on the angle θ between fiber orientation and B0. T2 values for the singlet C2 peak of gastrocnemius carnosine are inversely proportional to the C4 dipolar coupling strength (R2 = 0.97, P < 0.001), which in turn is a function of foot orientation. This dependence indicates that careful positioning of the foot while acquiring lower leg muscle spectra is important to obtain reproducible carnosine concentrations. As proton magnetic resonance spectroscopy of carnosine is currently used to non-invasively estimate the muscle fiber typology, these results have important implications in sport science.

SYNTHESIS AND ANTIOXIDANT ACTIVITY OF THIADIAZINE DERIVATIVES WITH PHENOLIC FRAGMENTS

A series of thiocarbohydrazones based on 3,5-di-tert-butyl-4-hydroxybenzaldehyde, salicylaldehyde, vanillin and 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde were synthesized. The reaction between thiocarbohydrazones and bromoacetylcoumarin was used to obtain and characterize a number of thiadiazine derivatives containing a phenolic fragment. The yields were 56–90%. The structural properties of the synthesized substances were studied by IR-Fourier, 1H, 13C NMR spectroscopy. In the IR spectra of thiadiazines there are characteristic bands of the stretching vibrations of the OH group (3622 cm-1), N-H bond (3450 cm-1), double bonds C=C and C=N 1608 and 1541 cm-1, respectively. In contrast to the spectrum of the starting compounds, there is a peak corresponding to vibrations of the C=O bond (1722 cm-1), which appeared due to the coumarin fragment. The 1Н NMR spectra of the obtained compounds contain peaks at 3.9 ppm, corresponding to the protons of the thiadiazine fragment. There are no signals at 6.8 ppm, related to the CH proton of the thiazole ring, and there is also a set of peaks in the region of 7.5-8.4 ppm., characteristic of the coumarin ring. Antioxidant activity of all products was determined in vitro: radical cation inhibition activity was determined using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) and electron donating activity was determined by ferric reduction ability using the ferricyanide/Prussian blue method. In both cases, agidol was used as a standard. All tested substances showed higher activity in both tests compared to the standard. The best antioxidant properties in both methods were shown by the derivative of 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde, thiadiazine based on salicylaldehyde also showed high antiradical activity, and thiadiazine with a fragment of 2-methoxyphenol showed good ferric-reducing properties.

Chirality Generated by Hindered Rotations in Platinum(II)‐Pyridine Complexes

AbstractThe reaction of trans‐[Pt(DMSO)2MeCl] with 2‐alkylsubstituted pyridines pyR affords a series of complexes of the type [Pt(pyR)(DMSO)MeCl]. These complexes are rare examples of organometallic square‐planar complexes having four different ligands. Of the three possible geometric isomers, only the trans(N,S)‐[Pt(pyR)(DMSO)MeCl] was observed in solution and isolated in the solid state. However, the lack of chirality typical to square planar geometry can be resolved in several ways one of which is described in this paper. 1H NMR studies reveal diastereotopicity of the DMSO methyls, as well as the CH2 protons in the ethyl‐ and neopentyl‐pyridine complexes and the methyls in the isopropyl‐pyridine derivative. This observation can be ascribed to restricted rotations around the Pt−N bond, thus resulting in the presence of planar chirality for these complexes. Additionally, large downfield shifts in the 1H NMR spectra of the α C−H protons in the pyridine substituents suggested the presence of Pt⋯H−C interactions, confirmed via single crystal X‐ray studies in the case of the isopropyl complex [Pt(pyip)(DMSO)MeCl] (4), which shows an apical Pt⋯H interaction with a short 2.585 Å distance. DFT calculations shed light into the stability of these complexes and the influence of the pyridine‐substituent on their chiral configuration.

Analytical descriptions of (multiple-contact) cross-polarization dynamics and spin-lattice relaxation in solid alanine

In this work, several exact and approximate analytical solutions to the quantum master equation are derived using both classical and non-classical coupling models to describe the kinetics of Hartmann-Hahn cross-polarization (HHCP) and multiple-contact CP (MCCP). Moreover, the analytical solution originally obtained by Naito and McDowell [J. Chem. Phys. 84 (1986) 4181.] is shown to be incorrect and the different regimes of spin diffusion and T1ρ relaxation are characterized by the amplitude of the second stage of the HHCP dynamics and the HHCP/MCCP crossing time. The analysis of the 1H–13C HHCP and MCCP dynamics together with (Lee-Goldburg) 1H T1ρ relaxation experimental data provides a consistent picture of spin dynamics in solid alanine and explains the apparent discrepancies previously observed between T1ρ and T1 relaxation measurements. The CH and CH3 protons relax as expected via spin diffusion towards the NH3 protons but the assumption of common proton spin temperature, in which the bottleneck of relaxation is at the NH3 sites, generally valid for T1 relaxation breaks down for T1ρ relaxation. A diffusion-limited situation in which nuclear Zeeman energy is transferred to the lattice faster than can be supplied by spin diffusion is observed instead.

NMR spectroscopy based configurational and compositional analysis of isobornyl methacrylate—Acrylonitrile copolymers

The authors conducted free radical polymerization using an initiator to synthesize a copolymer of isobornyl methacrylate—Acrylonitrile (I/A). The reactivity ratios of I (r1) and A (r2) monomers were determined as r1 = 1.63 ± 0.14, r2 = 0.61 ± 0.06 for linear KT (Kelen–Tudos) method and r1 = 1.58, r2 = 0.60 for the EVM (Error-in-Variable Method). We interpreted 1H and 13C{1H} NMR spectra of the I/A copolymers using DEPT-135 and 2D HSQC spectra. The α-CH3 carbon in the I-unit was identified and confirmed using a 2D HSQC NMR spectrum, up to the level of triad of compositional and configurational sequences. The CH (C14) and β-CH2 carbon peaks were also identified up to the triad level and higher, respectively. A 2D TOCSY spectrum revealed geminal and vicinal interactions within various CH and β-CH2 protons. A 2D HMBC NMR spectrum provided a complete assignment of the coupling between nitrile, carbonyl, and quaternary carbons with CH3 and CH2 protons.

Intramolecular Hydrogen Bonding in N6-Substituted 2-Chloroadenosines: Evidence from NMR Spectroscopy.

Two forms were found in the NMR spectra of N6-substituted 2-chloroadenosines. The proportion of the mini-form was 11-32% of the main form. It was characterized by a separate set of signals in COSY, 15N-HMBC and other NMR spectra. We assumed that the mini-form arises due to the formation of an intramolecular hydrogen bond between the N7 atom of purine and the N6-CH proton of the substituent. The 1H,15N-HMBC spectrum confirmed the presence of a hydrogen bond in the mini-form of the nucleoside and its absence in the main form. Compounds incapable of forming such a hydrogen bond were synthesized. In these compounds, either the N7 atom of the purine or the N6-CH proton of the substituent was absent. The mini-form was not found in the NMR spectra of these nucleosides, confirming the importance of the intramolecular hydrogen bond in its formation.

Ionic Liquid Induced p-Nitrophenol prototropism

The manuscript “Ionic Liquid Induced p-Nitrophenol Prototropism” deals with the acid-base properties of p-Nitrophenol molecule in the presence of two different Ionic Liquids (ILs). Prototropic equilibria of p-Nitrophenol (PNP) have been studied in water, ethanol, carbon tetrachloride, chloroform, cyclohexane and IL added aqueous solution with the help of Uv-vis absorbance spectroscopy. It was found that PNP mainly exists in neutral form when dissolved in ethanol, carbon tetrachloride, chloroform and cyclohexane. Interestingly, ground state ionization of PNP takes place in water and results into the formation of p-Nitrophenolate anion as a result of proton transfer to water and hence two absorbing species have been detected in the absorbance spectra. Inter-conversion of neutral to anionic and vice versa can be achieved with the addition of small amount of NaOH/HCl. Furthermore, in water/ethanol binary mixture both neutral and anionic forms exist. Interactions of surfactants sodium dodecyl sulfate (SDS) and cetrimonium bromide (CTAB) with neutral and ionic forms of PNP is also explored. To assess the potential role of ILs as a solubilizing media that facilitates proton-transfer reactions, p-Nitrophenol prototropism is investigated in water in the presence of small amount of added ILs. Interestingly, addition of small amount of hydrophilic IL, 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] or hydrophobic IL, 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6] into PNP dissolved in high pH water causes protonation of the already present p-Nitrophenolate anion. Protonation of p-Nitrophenolate is attributed due to presence of acidic C2-H protons in [bmim]+ cations associated with both ILs. Furthermore, the extent of protonation induced by addition of [BF4]− based IL is found to be much pronounced as compared to [PF6]− based IL having same cation due to difference in hydrolytic properties of [BF4]− based ILs when compared with [PF6]− based ILs. These findings could contribute to the technological applications for detection, removal and sensing of environmentally hazardous p-Nitrophenol and its ionic forms from water. The results presented in this work lead to a better understanding of prototropic behavior of PNP in IL based media as well as different organic solvents based media.

SYNTHESIS OF NEW HYBRID MOLECULES WITH 1,3,5-TRIAZINE AND HYDROQUINOLINE MOIETIES

The article describes a method for the synthesis of hybrid molecules based on the 1,3,5-triazine platform and containing additional pharmacophore fragments of 2,2,4-trimethyl-1,2-dihydroquinoline, 4-aryl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, indoline or piperidine. The obtained compounds are promising for studying their biological action. The described synthesis method includes the interaction of indolin-1-ylimidoguanidine and piperidine-1-ylimidoguanidine with carbon disulfide to form 4-amino-6-(indolin-1-yl)-1,3,5-triazine-2-thiol and 4-amino-6-(piperidin-1-yl)-1,3,5-triazine-2-thiol, respectively. 4-Amino-6-R-1,3,5-triazine-2-thiols have two nucleophilic centers: an amino and a mercapto group, so they can be introduced in subsequent reactions with electrophilic reagents such as alkyl halides. Alkylation of the latter with N-chloroacetyl derivatives of hydroquinolines gives hybrid heterocyclic matrices: 2-((4-amino-6-(indolin-1-yl)-1,3,5-triazin-2-yl)thio)-1-(2,2,4-trimethylquinolin-1(2H)-yl)ethan-1-ones, 2-((4-amino-6-(piperidin-1-yl)-1,3,5-triazin-2-yl)thio)-1-(2,2,4-trimethylquinolin-1(2H)-yl)ethan-1-ones, 2-((4-amino-6-(indolin-1-yl)-1,3,5-triazin-2-yl)thio)-1-(4-(4-aryl-2,2,4-trimethyl-3,4-dihydroquinolin-1(2H)-yl)ethan-1-ones and 2-((4-amino-6-(piperidin-1-yl)-1,3,5-triazin-2-yl)thio)-1-(4-(4-aryl-2,2,4-trimethyl-3,4-dihydroquinolin-1(2H)-yl)ethan-1-ones. The structure of the obtained compounds was characterized by high performance liquid chromatography with mass spectrometry, as well as by 1H and 13C NMR spectroscopy. For the compounds with the dihydroquinoline fragment in their structure, the singlet of the CH proton of the pyridine cycle of the hydroquinoline fragment, which is visible in the 5.56-5.61 ppm region, is characteristic. In turn, in the spectra of compounds with the tetrahydroquinoline fragment, there is a characteristic signal of the CH2 group of the hydropyridine cycle of the quinoline fragment in the form of two sets of multiplets at 0.99-1.09 and 1.61-1.71 ppm. The presence of several pharmacophore fragments in the molecules determines the high probability of their biological activity. The anticoagulant activity of 2-((4-amino-6-(piperidin-1-yl)-1,3,5-triazin-2-yl)thio)-1-(2,2,4-trimethylquinolin-1(2H)-yl)ethan-1-ones due to their inhibitory effect on blood coagulation factors Xa is described. A series of new hybrid molecules on the platform of 1,3,5-triazine containing additionally linearly linked hydroquinoline and indoline (piperidine) cycles was obtained in the course of this research. Initial screening of anticoagulant activity was performed and moderate activity of 2-((4-amino-6-(piperidin-1-yl)-1,3,5-triazine-2-yl)thio)-1-(2,2,4-trimethylquinoline-1(2H)-yl)ethane-1-ones against coagulation factor Xa was shown.

Infrared spectrum of the 1-cyanoadamantane cation: evidence of hydrogen transfer and cage-opening upon ionization.

The radical cations of diamondoids are important intermediates in their functionalization reactions and are also candidates as carriers for astronomical absorption and emission features. Although neutral diamondoids have been studied extensively, information regarding their radical cations is largely lacking, particularly for functionalized diamondoid derivatives. Herein, we characterize the structure of the 1-cyanoadamantane radical cation (C10H15CN+, AdCN+) using infrared photodissociation (IRPD) spectroscopy of mass selected AdCN+N2 clusters in the XH stretch range (2400-3500 cm-1) and dispersion-corrected density functional theory calculations (B3LYP-D3BJ/cc-pVTZ). A group of three distinct CH stretch bands are observed in the 2800-3000 cm-1 range, in addition to a highly redshifted absorption at 2580 cm-1 attributed to the acidic CH proton predicted by calculations. An unexpected broad absorption peaking at 3320 cm-1 is also detected and assigned to an NH stretch mode based on its width and frequency. Calculations indicate that hydrogen atom transfer (HAT) from the adamantyl cage (C10H15, Ady) to the N atom of the CN group yields lower energy structures, with an open-cage isomer exhibiting such hydrogen transfer being the global minimum on the potential energy surface. The energy barriers involved in the formation of this open-cage isomer are also lower than those calculated for generation of the analogous open-cage 1-amantadine cation isomer which has previously been identified by IRPD. The combined consideration of IRPD spectra and calculations indicates a major population of the nascent canonical closed-cage isomer and a smaller population of the global minimum isomer featuring both cage-opening and hydrogen transfer.

N-heterocyclic carbenes with three and six fluorous ponytails and their highly fluorophilic Rh and Ir complexes

Reactions of 1-methylimidazole and 1-(1-methylethyl)imidazole with (3-iodopropyl)tris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane gave the corresponding 1-alkyl-3-(3-(tris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl) silyl) propyl) imidazolium iodides 1 and 2. Reaction of imidazole in excess with (3-iodopropyl)tris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane afforded 1-(3-(tris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl) silyl) propyl) imidazole 3 which was further reacted with (3-iodopropyl)tris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane to produce the doubly tagged 1,3-bis[3-(tris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl) silyl) propyl] imidazolium iodide 4 and by anion exchange a tetrafluoroborate salt 5. The prepared imidazolium iodides 1,2, and 4 were then used as precursors in synthesis of chlorido(cycloocta-1,5-diene)rhodium or -iridium complexes bearing Nheterocyclic carbenes with one 3-[tris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silyl]propyl-substituent and methyl-, 1-methylethyl-and another 3-[tris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silyl]propyl-substituent on nitrogens, 6 – 11. The metal complexes were equimolar mixtures of conformational enantiomers as was best documented by the 1H NMR signals of diastereotopic CH2 protons next to nitrogen. Fluorophilicity fi as the natural logarithm of partition coefficient Pi between fluorous and organic phase of the complexes was determined in the standard solvent system (perfluoro)methylcyclohexane/toluene. All the complexes are fluorophilic with variation of fi between 0.96 and 4.06, the complexes with high values may be classified as highly fluorophilic (heavy fluorous).

Long-lived states of methylene protons in achiral molecules.

In nuclear magnetic resonance (NMR), the lifetimes of long-lived states (LLSs) are exquisitely sensitive to their environment. However, the number of molecules where such states can be excited has hitherto been rather limited. Here, it is shown that LLSs can be readily excited in many common molecules that contain two or more neighboring CH2 groups. Accessing such LLSs does not require any isotopic enrichment, nor does it require any stereogenic centers to lift the chemical equivalence of CH2 protons. LLSs were excited in a variety of metabolites, neurotransmitters, vitamins, amino acids, and other molecules. One can excite LLSs in several different molecules simultaneously. In combination with magnetic resonance imaging, LLSs can reveal a contrast upon noncovalent binding of ligands to macromolecules. This suggests new perspectives to achieve high-throughput parallel drug screening by NMR.

Investigation on the coacervation of fish scale gelatin hydrogel with seafood waste hydrolysates for the development of artificial fish bait: Physico-chemical, thermodynamic, and morpho-structural properties

The study dealt with the development of biopolymer based hydrogel artificial fish bait with hydrolysates derived from fish processing wastes. Fish scale gelatin (FSG) was used for the development of a hydrogel to which bioattractants extracted from seafood processing wastes of fish, squid and shrimp were added to prepare composite gels such as FSG-FH, FSG-SH and FSG-SPH, respectively. To understand the homogenesity and cross linking complexation of composite gels, the study aimed at investigating physico-chemical, thermodynamic, molecular and structural properties were analysed. The gel strength, melting point and thermal stability of the composite hydrogels were found to decrease marginally compared to the control gel, FSG. It could be understood that the crystalline structure at 2θ = 23° of the FSG-SH, and FSG-FH were not much altered compared to FSG gel. However, alteration in the crystalline structure in FSG-SPH was evident at 2θ = 27.3°. The TGA and DSC analysis revealed the reduction in the thermal stability of FSG on the addition of protein hydrolysates in the process of coacervation to get hydrogel based fish bait. Further, FESEM and AFM analysis indicated FSG-SH as the composite hydrogel with most compact and smooth surface was evident by Ra and Rq values. Among the composite gels, FSG-SH was found to have higher hydrophobicity due to enhanced gel structure. FTIR spectra of FSG and composite gels exhibitted similarity corresponding to amide-A, B, I, II and III bands. However, NMR analysis revealed the existence of notable difference with respect to chemical shift in the range of 7.0–7.75 ppm expressing the presence of aromatic protons of the amino acid phe and N–H protons of amide in all the composite gels. Further, NMR analysis confirmed the role of imino acids (δ CH2 & β CH2 protons) and hydrophobic amino acids (α-CH2 protons) in decrease the physical and thermal properties of the composite gels. The addition of protein hydrolysates with FSG was found to decrease the physical, thermal and structural properties, however improve the aromatic compounds of the composite gels.

Synthesis, Structure and Studies of Meso-Triaryl 22-Oxabenzonorroles.

The first examples of meso-triaryl 22-oxabenzonorroles were synthesized in 18-21% yields by oxidation of appropriate meso-triaryl oxabenzobilane. The key precursors, the meso-triaryl oxabenzobilanes were synthesized readily by treating 16-oxatripyrrane with (1H-indol-3-yl)(p-tolyl)methanol under acid catalyzed conditions. The meso-triaryl 22-oxabenzonorroles were obtained in free base form by following our simple straight-forward synthetic strategy. The X-ray structure obtained for meso-tritolyl 22-oxabenzonorroles revealed that the indole ring was deviated by an angle of 41.27° from the mean plane. The NMR studies supported the presence of diatropic ring current effect as inner NH and CH protons were observed in the upfield region. The absorption spectra of 22-oxabenzonorroles exhibited one strong Soret band and four weak Q-bands. The electrochemical studies revealed that the macrocycles are electron rich and undergo easier oxidations. The DFT and TD-DFT studies were in agreement with the experimental observations and NICS and HOMA values supports the aromatic nature of meso-triaryl oxabenzonorroles.

New One-Pot Pathway for the Synthesis of 2H–Pyrrolo[2,3-d]Pyrimidine-2,4-(3H)-Diones and 1H-Benzo[f]Indole-4,9-Dione Derivatives Substituted 3-Hydroxy-1,4-Naphthoquinonyl

One-pot three components effective methods are reported for the synthesis of two important families of organic compounds, 2H-pyrrolo[2,3-d]pyrimidine-2,4(3H)-diones substituted 5-(3-hydroxy-1,4-naphthoquinonyl) and 1H-benzo[f]indole-4,9-diones substituted 3-(3-hydroxy-1,4-naphthoquinonyl), by employment of new starting materials. The formers were prepared via the one-pot condensation reaction between phenylglyoxal, 2-hydroxynaphtoquinone and 2-amino-1,4-naphthoquinone derivatives and the later through the reaction of phenylglyoxal, 2-hydroxy naphthoquinone and 2-amino-1,4-naphthoquinone derivatives. The reaction medium for the synthesis of both procedures was acetic acid/water (1:1; v/v) at 100 °C, and various derivatives of these compounds were obtained with high-efficiency and identified by their IR, 1H- and 13C-NMR spectra. In spite of their apparent planar structures, the NMR spectra of some products shown asymmetric properties of CH2 protons or existence of two diastereomers due to restriction of Chydroxyquinoline˗Cpyrrol bonds, together with formation of relatively stable nonplanar eight membered ring resulted from hydrogen bond formation between hydroxynapthoquinone’s OH and carbonyl groups of uracil motifs.

In Silico and In Vitro Antiproliferative Activity Assessment of New Schiff Bases

AbstractIn this study, a series of new Schiff bases, based on a pyrimidine core, were synthesized in two steps. The structures of these newly synthesized Schiff bases were completely characterized. The presence of characteristic ‐N=CH proton peaks proving the formation of imine supports the structures of the compounds. The cytotoxic activity studies were done towards human cancer cell lines. The results show that the related molecules had antiproliferative activity on cancerous cells. To compare the chemical and biological activities of pyrimidine derivatives were performed using Gaussian software and Maestro Molecular modeling platform by Schrödinger, respectively. Afterwards, ADME/T analysis was performed to examine the possibility of pyrimidine derivatives being drugs.

Bulky Selenium Ligand Stabilized Trans-Palladium Dichloride Complexes as Catalyst for Silver-Free Decarboxylative Coupling of Coumarin-3-Carboxylic Acids.

This report describes the syntheses of three new trans-palladium dichloride complexes of bulky selenium ligands. These complexes possess a Cl-Pd-Cl rotor spoke attached to a Se-Pd-Se axle. The new ligands and palladium complexes (C1-C3) were characterized with the help of NMR, HRMS, UV-Vis., IR, and elemental analysis. The single-crystal structure of metal complex C2 confirmed a square planar geometry of complex with trans-orientation. The X-ray structure revealed intramolecular secondary interactions (SeCH-Cl) between chlorine of PdCl2 and CH2 proton of selenium ligand. Variable-temperature NMR data shows coalescence of diastereotopic protons, which indicates pyramidal inversion of selenium atom at elevated temperature. The relaxed potential energy scan of C2 suggests a rotational barrier of ∼12.5 kcal/mol for rotation of chlorine atom through Cl-Pd-Cl rotor. The complex C3 possesses dual intramolecular secondary interactions (OCH2 -Cl and SeCH2 -Cl) with stator ligand. Molecular rotor C2 was found to be a most efficient catalyst for the decarboxylative Heck-coupling under mild reaction conditions. The protocol is applicable to a broad range of substrates with large functional group tolerance and low catalyst loading (2.5 mol %). The mechanism of decarboxylative Heck-coupling reaction was investigated through experimental and computational studies. Importantly the reaction works under silver-free conditions which reduces the cost of overall protocol. Further, the catalyst also worked for decarboxylative arylation and decarboxylative Suzuki-Miyaura coupling reactions with good yields of the coupled products.

Biological Evaluation of Platinum(II) Sulfonamido Complexes: Synthesis, Characterization, Cytotoxicity, and Biological Imaging.

Platinum-based compounds are actively used in clinical trials as anticancer agents. In this study, two novel platinum complexes, (C1 = [PtCl2(N(SO2quin)dpa)], C2 = [PtCl2(N(SO2azobenz)dpa)]) containing quinoline and azobenzene appended dipicolylamine sulfonamide ligands were synthesized in good yield. The singlet attributable to methylene CH2 protons of the ligands of C1 and C2 appears as two doublets in 1H NMR spectra, which confirms the presence of magnetically nonequivalent protons upon coordination to platinum. Structural data of N(SO2quin)dpa (L1), N(SO2azobenz)dpa (L2) and PtCl2(N(SO2quin)dpa) confirmed the formation of the desired compounds. Time-dependent density functional theory calculations suggested that the excitation of L1 show quin-unit-based π⟶π∗ excitations (i.e., ligand-centered charge transfer, LC), while C1 shows the metal-ligand-to-ligand charge-transfer (MLLCT) character. L1 displays intense fluorescence from the 1LC excited state, while C1 gives phosphorescence from the 3LC state. Mammalian cell toxicity of ligands and complexes was assessed with NCI–H292 nonsmall-cell lung cancer cells. Further, C1 and C2 showed significantly low IC50 values compared with N(SO2azobenz)dpa and PtCl2(N(SO2quin)dpa). Fluorescence imaging data of both ligands and complexes revealed the potential fluorescence activity of these compounds for biological imaging. All four compounds are promising novel candidates that can be further investigated on their usage as potential anticancer agents and cancer cell imaging agents.