Synthesis and Antiviral Evaluation of 3′-Fluoro-4′-modified-5′-norcarbocyclic Nucleoside Phosphonates

The synthesis and anti-HIV evaluation of hitherto unknown 3′-fluoro-5′-norcarbocyclic nucleoside phosphonates bearing adenine with modifications at the 4′ position (ethynyl, vinyl, ethyl, hydroxymethyl) is described. One of the synthesized compounds was found to be an inhibitor of HIV-1 replication, but with moderate efficiency relative to (R)-9-(2-phosphonylmethoxypropyl)adenine ((R)-PMPA, tenofovir), with no concomitant cytotoxicity.     

Synthesis and Structural Characterization of Triorganotin(IV) Derivatives with 2,2′-Thiodiglycolic Acid and 3,3′-Thiodipropionic Acid

The synthesis and structural characterization of four novel triorganotin(IV) complexes, {(R₃Sn)₂[C₂H₄S(COO)₂]} _n (R = Me: 1), {(R₃Sn)₄[C₂H₄S(COO)₂]₂} _n (R = nBu: 2), {(R₃Sn)₂[C₄H₈S(COO)₂]} _n (R = Me: 3; nBu: 4) were obtained by the reaction of 2,2′-thiodiglycolic acid, 3,3′-thiodipropionic acid and the corresponding R₃SnCl (R = Me, nBu) with potassium hydroxide in methanol. All the complexes were characterized by elemental analysis, Fourier transform infrared and nuclear magnetic resonance (¹H, ¹³C, ¹¹⁹Sn) spectroscopies, X-ray crystallography and thermogravimetric analyses. The crystal structures show that 1 has 2D network structure in which 2,2′-thiodiglycolic acid acts as a tetradentate ligand coordinating to the trimethyltin(IV) ions. Complexes 2, 3, and 4 are 3D metal-organic framework structures in which the deprotoned acids act as a tetradentate ligand afforded by four oxygen atoms.     

Selective Extraction and Spectrophotometric Determination of Vanadium(V) with N-Hydroxy-N-p-chlorophenyl-N′-(2-methyl-5-chloro)phenyl-p-toluamidine Hydrochloride and Various Monobasic Carboxylic Acids

Abstract

N-Hydroxy-N-p-chlorophenyl-N′-(2-methyl-5-chloro)phenyl-p-toluamidine hydrochloride (HCPMCPTH), a newly synthesized bidentate chelating agent, reacts with vanadium(V) in the presence of monobasic carboxylic acids to give blue-violet water-insoluble adducts. The adducts have been extracted into various organic solvents such as chloroform, benzene, and carbon tetrachloride, and employed for the spectrophotometric determination of vanadium(V) and its separation from diverse ions. Investigations of the vanadium-HCPMCPTH-carboxylic acid complexes by spectrophotometric and solvent extraction techniques showed that the complex had the composition VO(OAm)₂OH.HOOCR (where HOAm = hydroxyamidine and HOOCR = carboxylic acid). The molar absorptivity and wavelength of maximum absorption of the mixed complex depend on the nature of the carboxylic acid used.     

Synthesis,characterization and crystal structure of one Mn(II) complex with 4,4′-bisimidazolylbiphenyl and 4,4′-sulfonyldibenzoic acid

One new title compound [Mn₃(BIBP)(sdb)(NO₂⁻)₂(H₂O)₂]_n·2DMF (1) (BIBP = 4,4′-bisimidazolylbiphenyl, sdb = 4,4′-sulfonyldibenzoic acid) has been synthesized under hydrothermal condition. The title compound was characterized by IR spectra, thermal analysis, single crystal and powder X-ray diffraction. Magnetic susceptibility measurements indicate that compound 1 exhibits antiferromagnetic coupling interaction.     

Coupling Interrupted Fischer and Multicomponent Joullié-Ugi to Chase Chemical Diversity: from Batch to Sustainable Flow Synthesis of Peptidomimetics

The generation of peptidomimetic substructures for medicinal chemistry purposes requires effective and divergent synthetic methods. We present in this work an efficient flow process that allows quick modulation of reagents for Joullié-Ugi multicomponent reaction, using spiroindolenines as core motifs. This sterically hindered imine equivalent could successfully be diversified using various isocyanides and amino acids in generally good space-time yields. A telescoped flow process combining interrupted Fischer reaction for spiroindolenine synthesis and subsequent Joullié-Ugi-type modification resulted in product formation in very good overall yield in less than 2 hours compared to 48 hours required in batch mode. The developed protocol can be seen as a general tool for rapid and facile generation of peptidomimetic compounds. We also showcase preliminary biological assessments for the prepared compounds.     

Sulfonated polyimide copolymers based on 4,4′-diaminostilbene-2,2′-disulfonic acid and 3,5,3′,5′-tetramethylbenzidine with enhanced solubility

A new series of six-membered ring sulfonated polyimides with different combinations of two comonomers in the nonsulfonated diamine was prepared by one-step high-temperature polycondensation in m-cresol to improve the solubility of the resulting sulfonated polyimides. They are based on 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-diaminostilbene-2,2-disulfonic acid sulfonated diamine, and equimolar mixture of 3,5,3′,5′-tetramethylbenzidine (TMB) and 4,4′-oxydianiline, bis(4-aminophenyl)methane, or bis(4-(aminophenoxy)-4-phenyl)isopropylidene nonsulfonated diamines. The introduction of TMB comonomer in the nonsulfonated diamine resulted in a remarkable improvement in the solubility of the resulting polyimides in comparison with the corresponding single-monomer nonsulfonated diamine polyimides. Flexible, transparent, and tough membranes were prepared by solution casting method from the different polyimides. The membranes were characterized with FTIR and ¹H-NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, water uptake, and ion-exchange capacity measurements. They exhibit high thermal stability and good correlation between the ion-exchange capacity and water uptake values.     

Synthesis of Substituted 5′-Aminoadenosine Derivatives and Evaluation of Their Inhibitory Potential toward CD73

Derivatives of 5′-aminoadenosine containing methyl carboxylate, methyl phosphonate, gem-bisphosphonate, bis(methylphosphonate), and α-carboxylmethylphosphonate or phosphonoacetate moieties were synthesized from key intermediate 5′-aminonucleoside. These nucleotide analogues were envisaged as 5′-mono- or diphosphate nucleoside mimics. All compounds were evaluated for CD73 inhibition in a cell-based assay (MDA-MB-231) and toward the purified recombinant protein. Most of them failed to reach significant inhibition of AMP hydrolysis by CD73 at 100 μm . Among the new compounds, the most interesting candidates, 5 (5′-deoxy-5′-N-phosphonomethyladenosine) and 7 (5′-deoxy-5′-N-(ethoxyphosphorylacetate)adenosine), inhibited recombinant CD73 by 36 and 46 % and cellular CD73 by 61 and 45 % at 100 μm , respectively. Molecular modeling partially explains this lack of activity, as the initially predicted docking scores had been encouraging, especially for compound 9 .     

Synthesis, Structure and Luminescence Property of Cadmium(II) Coordination Polymer with Mixed 5-(Oxidediphenylphosphino)isophthalic Acid and 4,4′-Bipyridine Ligands

A new metal–organic framework {[Cd(L)(4,4′-bpy)]₂·5H₂O} _n (1) had been synthesized by hydrothermal reaction of 5-(oxidediphenylphosphino)isophthalic acid, Cd(II) nitrate, NaOH and 4,4′-bipyridine (4,4′-bpy) as co-ligand. The novel compound was characterized by single crystal X-ray diffractometry as well as FTIR spectrum. Adjacent eight-member (C₂Cd₂O₄) rings are connected each other through pairs of L^2? ligands to result in a 1D double chain. Such ribbons are interconnected together by 4,4′-bpy to generate a 2D pillared layer, which are further held together by rich O–H···O hydrogen bonds to give a 3D supramolecular network. Solvent water molecules play an important role to bridge adjacent layers to form a 3D supramolecular architecture. The luminescence property and thermogravimetric analysis of title complex were investigated.     

Synthesis and trans-ureation of N,N’-diphenyl-4,4′-methylenediphenylene biscarbamate with diamines: a non-isocyanate route (NIR) to polyureas

A non-isocyanate route (NIR) of making polyureas of high molecular weight has been found through trans-ureation of N,N’-diphenyl-4,4′-methylenediphenylene biscarbamate (4,4′-DP-MDC) with a variety of diamines and mixed diamines. The preparation of 4,4′-DP-MDC was achieved readily by carbonylation of 4,4′-methylenedianiline (4,4′-MDA) with diphenyl carbonate (DPC) using organic acids as catalysts. It was found that the highest yield (99%) of pure 4,4′-DP-MDC can be isolated in a toluene solution under mild conditions co-catalyzed by benzoic acid and tertiary amine. Trans-ureation of 4,4′-DP-MDC with aliphatic amines indicated that the process is a highly solvent dependent process and was found to be extremely facile in dimethyl sulfoxide (DMSO) at 80 °C and in tetramethylene sulfone (TMS) at 140 °C in absence of any catalyst. Particularly, the most effective polymerization process was developed using tetramethylene sulfone (TMS) as the solvent under reduced pressure for concurrently distilling off phenol from the reaction mixture during the polymerization in a shifting equilibrium towards polyurea. However, this solvent-assisted trans-ureation was found to be in-efficient when N,N’-dimethyl-4,4′-methylenediphenylene biscarbamate (4,4′-DM-MDC) was used in a similar condition for comparison. Thus, an efficient green-chemistry process has been developed based on 4,4′-DP-MDC in making urea prepolymers, urea elastomers and urea plastics all in excellent yields without using reactive methylenediphenylene diisocyanate (MDI) or any catalysts in the trans-ureation polymerizations.     

Synthesis and thermal properties of block copolyetheresters with poly(pentamethylene p,p′-bibenzoate) segments

The block copolyetheresters with hard segments of poly(pentamethylene p,p-bibenzoate) and soft segments of poly (tetramethylene ether) were prepared by melt polycondensation of dimethyl-p,p-bibenzoate, 1,5-pentanediol and poly (tetramethyene ether) glycol (PTMEG) with molecular weights of 650, 1000 and 2000. The results by NMR indicate that the polymer composition is determined by the charge molar ratio (x) of PTMEG to dimethyl-p,p-bibenzoate. The thermal transitions of the block copolyetheresters were investigated by DSC in combination with X-ray diffraction and polarized microscopy. Some block copolyetheresters exhibit a monotropic smectic phase due to the presence of the poly (pentamethylene p,p-bibenzoate) segments. As the molar content of PTMEG increases, the average sequence length of the polyester segments decreases, the isotropic-smectic transition temperature and the smectic order decrease accordingly. When x is as high as 0.3, the block copolyetheresters exhibit no liquid crystallinity.     

Synthesis and Polymerization of Bismaleimide Derived from 5(6)-amino-1(4′-aminophenyl)-1,3,3′-trimethyl indane

The acid-catalyzed dimerization of α-methyl styrene led to the formation of trimethyl phenyl indane, which on nitration followed by reduction using hydrazine hydrate gave 5(6)-amino-1(4′-aminophenyl)-1,3,3′-trimethyl indane. This aromatic diamine was used to synthesize bismaleamic acid and imidized to yield bismaleimide. The bismaleamic acid was converted to prepolymer directly by imidizing it in refluxing toluene. All the materials synthesized were characterized using FTIR, ¹H and ¹³C NMR. The direct inlet mass spectral characterizations were carried out for bismaleamic acid, bismaleimide and bismaleimide prepolymer. The fragmentation pattern was discussed in detail and the structure proposed was confirmed. The thermogravimetric studies were done for all the materials and kinetic parameters (energy of activation and frequency factor) were calculated using Dharwadkar and Kharkhanavala method. The structural changes occurring in the thermally polymerized bismaleimide and bismaleimide prepolymer were discussed.     

Design,Synthesis and Bioactivity of N-Glycosyl-N′-(5-substituted phenyl-2-furoyl) Hydrazide Derivatives

Condensation products of 5-substituted phenyl-2-furoyl hydrazide with different monosaccharides d-glucose, d-galactose,d-mannose, d-fucose and d-arabinose were prepared. The anomerization and cyclic-acyclic isomers were investigated by ¹H NMR spectroscopy. The results showed that, except for the d-glucose derivatives, which were in the presence of β-anomeric forms, all derivatives were in an acyclic Schiff base form. Their antifungal and antitumor activities were studied. The bioassay results indicated that some title compounds showed superior effects over the commercial positive controls.     

Synthesis and Aggregation of Novel Sugar-Based Gemini Surfactant with a N,N′-Acetylethylenediamine Spacer in Aqueous Solution

A novel sugar-based Gemini surfactant with a N,N′-acetylethylenediamine spacer (N,N′ (N-dodecyl-2-D-glucosaminyl acetyl) ethylenediamine, Glu(12)-(AA)-Glu(12)), was synthesized with D-(+)-Glucono-1,5-lactone as starting material in three steps. The surfactant's structure was confirmed using ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization mass spectrometry (ESI-MS). The aggregation behavior of Glu(12)-(AA)-Glu(12) in aqueous solution at pH 4.0, 7.0, and 10.0 was investigated by surface tension, dynamic light scattering (DLS), and cryogenic transmission electron microscopic (Cryo-TEM) measurements. The surface tension measurement shows that the critical micelle concentration (CMC) of Glu(12)-(AA)-Glu(12) is at the concentration level of 10⁻⁵ mol·L⁻¹ at 25 °C, which is significantly lower than that of corresponding monomeric sugar-based surfactants. Compared with such sugar-based Gemini surfactants with similar hydrophilic spacers, Glu(12)-(AA)-Glu(12) demonstrated similar or slightly lower surface activity. The CMC value of Glu(12)-(AA)-Glu(12) underwent a slight decrease with the increase of pH. DLS and Cryo-TEM measurements reveal that Glu(12)-(AA)-Glu(12) forms micelles at acidic pH (pH 4.0) and the micelles are transformed into vesicles at neutral or high pH (pH 7.0, 10.0). The microstructural transformation of Glu(12)-(AA)-Glu(12) aggregates is related to the protonation state of its two tertiary amines in the head groups versus pH.     

A tetranuclear pyrophosphate-bridged Cu(II) complex with 4,4′-bipyridine and 1,10-phenanthroline: Synthesis,structural, and magnetic properties

A new tetranuclear pyrophosphate-bridged Cu(II) complex with 4,4′-bipyridine and 1,10-phenanthroline [Cu₄(phen)₄(bpy)₂(P₂O₇)₂]·10H₂O (1) has been hydrothermal synthesized and characterized by single-crystal X-ray analysis, element analysis, IR spectroscopy, TG analysis, and UV–vis spectra. Variable-temperature magnetic susceptibility measurements show the occurrence of antiferromagnetic interactions between the neighbor Cu(II) centers in 1. The analysis of the magnetic data in the whole temperature range allows the determination of the value of the intramolecular magnetic coupling (J = − 13.16 cm^− 1).     

Can Forest Trees Cope with Climate Change?—Effects of DNA Methylation on Gene Expression and Adaptation to Environmental Change

Epigenetic modifications, including chromatin modifications and DNA methylation, play key roles in regulating gene expression in both plants and animals. Transmission of epigenetic markers is important for some genes to maintain specific expression patterns and preserve the status quo of the cell. This article provides a review of existing research and the current state of knowledge about DNA methylation in trees in the context of global climate change, along with references to the potential of epigenome editing tools and the possibility of their use for forest tree research. Epigenetic modifications, including DNA methylation, are involved in evolutionary processes, developmental processes, and environmental interactions. Thus, the implications of epigenetics are important for adaptation and phenotypic plasticity because they provide the potential for tree conservation in forest ecosystems exposed to adverse conditions resulting from global warming and regional climate fluctuations.     

Dithieno[3,2-b:2′,3′-d]pyrrole-based materials: Synthesis and application to organic electronics

The application of dithieno[3,2-b:2′,3′-d]pyrroles (DTPs) in conjugated organic polymers has resulted in a variety of materials with reduced and low band gaps that exhibit high carrier mobilities, as well as enhanced solution and solid-state fluorescence. While DTP-based materials date back to the early 1990s, significant advances in the preparation and scope of these materials have been reported over the past decade. In this current report, we provide the first full review of DTP-based materials, highlighting in particular the recent advances made in the synthesis of both monomeric DTPs and their resulting materials, as well as the current progress of their application to various devices, including FETs, OPVs, OLEDs, and electrochromics.     

Efficient and selective conversion of hexose to 5-hydroxymethylfurfural with tin–zirconium-containing heterogeneous catalysts

Efficient and selective production of 5-hydroxymethylfurfural (HMF) from the hexose is achieved in the presence of heterogeneous Sn-based catalyst. The mixed SnO₂–ZrO₂ is prepared from zirconium n-propoxide and different metal Sn precursors using Sol–gel method. The sulfated SnO₂–ZrO₂ (SO₄^2 −/SnO₂–ZrO₂) is obtained by the impregnation method with H₂SO₄ solution. All catalytic materials are detected with XRD, TG, SEM, TEM and BET techniques in order to reveal the physical properties and structures of these materials. When these materials were used in the dehydration of fructose, it was found that the suitable ratio of Sn/Zr is 0.5, and the catalytic activity of SO₄^2 −/SnO₂–ZrO₂ is higher than that of SnO₂–ZrO₂ where more than 75.0% yield of HMF was obtained for 2.5 h at 120 °C. The effects of reaction temperature and reaction time were also investigated. Moreover, the recycling experiment of catalyst shows that the catalytic activity can be almost kept unchanged after being used five times.     

Synthesis and characterization of iron(II) and iron(III) complexes with a tridentate O,N,O′-ligand

The coordination chemistry of the ligand precursor 1-benzoyl-4,5-dihydro-3,5-bis(trifluoromethyl)-1H-pyrazol-5-ol (1a) to iron(II) acetate was studied. In dependence of the added co-ligand different complex geometries were observed. In case of 4-dimethylaminopyridine (DMAP) as co-ligand an octahedral iron(II) complex was found with an O,N,O′-coordination of the tridentate ligand (1a-2H), in which the ligand is planar, the oxygen donors are trans to each other, and the nitrogen donor is in a cis position. The other coordination sites on the iron center are occupied by DMAP ligands. In contrast to that, with triphenylphosphane as the co-ligand an oxidation process took place, which revealed an octahedral iron(III) complex with a comparable geometry for the tridentate ligand (O,N,O′-coordination, 1a-2H) demonstrating the usefulness of 1a-2H to stabilize different oxidation states. The additional coordination sites are occupied by one triphenylphosphane oxide and ethoxide ligands. Interestingly, the ethoxide ligands act as bridging ligands to form a bimetallic complex.