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Here, this study overcomes the current barriers to efficient solid-phase synthesis of high-generation dendrimers by decreasing the loading ratio on the resin. G7 inverse poly(amidoamine) dendrimer is now prepared, for the first time, through a solid-phase synthesis using only 50% of the available reactive sites and by choosing a large resin. This preparation takes only 15 d to afford highly pure product in 80% yield with precipitation being the only purification procedure used. The results clearly show the amount of the initial monomer loaded on the resin to be a vital factor for the ability to use solid-phase synthesis to produce large dendrimers. This finding also sets stage for the applications of solid-phase synthesis for the preparation of other macromolecules. [ABSTRACT FROM AUTHOR]

For effective gene delivery, structural degradation of synthetic carriers is crucial to the release of nucleic acids on the transfection time scale. In this study, we have synthesized the amphiphilic dendritic scaffolds with a photolabile o-nitrobenzyl (o-NB) group that can enable the structural decomposition and controlled release of nucleic acids under active light stimulation. The amphiphilic counterpart composed of a lipophilic cholesterol and a hydrophilic poly(amido amine) (PAMAM) dendron allows the self-assembly into a core–shell-like pseudodendrimer above the critical aggregation concentration (CAC) of approximately 20 μM. On the basis of electrostatic interaction, the polycationic pseudodendrimers are capable of forming stable complexes with polyanionic cyclic reporter genes under low charge excess values, suggesting substantial binding affinity of the dendron assembly toward circular DNA. Because the o-NB group in the dendritic structure undergoes efficient photolytic cleavage, an in vitro test shows that thus-formed “dendriplexes” are readily dissociated under 365 nm light irradiation, causing effective dendron degradation accompanied by DNA release. This photochemical strategy provides an opportunity to control gene binding and release in a spatiotemporal manner. [ABSTRACT FROM AUTHOR]

For the first time, structural informationregarding the role ofsimvastatin in bone anabolism is described, and a bone-specific statinis introduced. Polyaspartate-conjugated simvastatin was synthesizedby solid-phase synthesis with the assistance of microwave irradiation.It displays significant bone targeting and bone formation with lesstoxicity than simvastatin. [ABSTRACT FROM AUTHOR]

Abstract: A facile alloy–dealloy technique performed in aqueous media was employed to prepare a nanoporous gold (NPG) electrode that demonstrated extremely high sensitivity toward hydrazine oxidation. An Ag∼60Au∼40 alloy was electrodeposited at a constant potential on sequentially Cr- and Au-deposited indium tin oxide (Au/Cr/ITO) from a bath that contained sulfuric acid, thiourea, HAuCl4·3H2O, and AgNO3. The dealloying step was performed in concentrated HNO3, where Ag in the alloy was selectively oxidized to leave the NPG structure. The NPG electrode was employed to study the hydrazine oxidation in basic phosphate buffer solution (PBS), and the results were compared with those obtained using the gold nanoparticle (AuNP)-modified ITO (AuNP/ITO) electrode. The NPG electrode demonstrated an unusual surface-confined behavior, which probably resulted from the thin-layer characteristics of the nano-pores. Hydrazine was detected by hydrodynamic chronoamperometry (HCA) at +0.2V (vs. Ag/AgCl). The steady-state oxidative current exhibited a linear dependence on the hydrazine concentration in the concentration range of 5.00nM–2.05mM, and the detection limit was 4.37nM (σ =3). This detection limit is the lower than the detection limits reported in the current literature concerning the electrochemical detection of hydrazine. The NPG electrode indeed demonstrates greater stability after hydrazine detection than the AuNP/ITO electrode. [Copyright &y& Elsevier]

The Ru(II)-nitrite complex, Ru4, is explored to release nitric oxide (NO) under acidic conditions and selectively induce a cytotoxic effect towards SK-MEL-28 cisplatin-resistant malignant melanoma cells. These findings suggest that targeting the tumor-associated pHe level could be an effective strategy for the drug function of Ru(II)-nitrite compounds. [ABSTRACT FROM AUTHOR]

Peptidols were prepared through the reductive cleavage of benzotriazole intermediates obtained from the on‐bead activation of 3,4‐diaminobenzoyl linkers. Remarkably, this method used commercially available amino acid residues and resins without further modification. Pure peptidols were collected with only filtration in 49%–87% yield. Only the derivatives with aspartic acid as the first C‐terminal residue required sophisticated chromatography purification. Esters and carboxylic acids were identified as side products and were suppressed by additional reduction or reduction in DMF. Remarkably, the reduction of peptides with the first aspartic acid residue at the C‐terminal afforded a C‐terminal lactone, which could be reduced by deprotection at 0 °C. For the synthesis of branched peptidols, the bulky wedge structures of the branched peptides resulted in low total yields, which were improved to 23%–28% by using peripheral Boc groups and SPPS on the Tental gel resin. In addition, this method gave two peptaibols, SPF‐5506‐A4 and Ac‐Gramicidin A, in 11% and 46% yields, respectively. [ABSTRACT FROM AUTHOR]

Background: The rapid detection and efficient properties of surface‐enhanced Raman scattering (SERS) have been widely exploited in food safety. Purpose: In this study, the SERS impact of cysteine‐functionalized gold core‐silver shell bimetallic nanoparticle (Au@Ag@CysNPs) substrates with different pH treatments on pesticide compounds was examined. Results: The pH‐dependent SERS impact of Au@Ag@CysNPs on detecting pesticide compounds exhibited different enhancements over the pH range of 2–11 and exited the highest enhancement at a pH of 5 for thiabendazole and thiram pesticides. The prepared Au@Ag@CysNPs were further utilized in SERS‐based rapid detection of pesticides on apple peels by directly dropping Au@Ag@CysNPs on the surface of the samples, where the target molecules could be identified without elution or extraction. These findings revealed that this Au@Ag@CysNPs substrate exhibited excellent SERS performances for pesticide compounds and good stability. With additional optimization, detection limits of 0.1 ng/cm2 for thiabendazole and thiram on apple peels were obtained. [ABSTRACT FROM AUTHOR]

Triple-negative breast cancer (TNBC) is insensitive to target therapy for non-TNBC and needs novel drug discovery. Extracts of the traditional herb Boesenbergia plant in Southern Asia exhibit anticancer effects and contain novel bioactive compounds but merely show cytotoxicity. We recently isolated a new compound from B. stenophylla, stenophyllol B (StenB), but the impact and mechanism of its proliferation-modulating function on TNBC cells remain uninvestigated. This study aimed to assess the antiproliferative responses of StenB in TNBC cells and examine the drug safety in normal cells. StenB effectively suppressed the proliferation of TNBC cells rather than normal cells in terms of an ATP assay. This preferential antiproliferative function was alleviated by pretreating inhibitors for oxidative stress (N-acetylcysteine (NAC)) and apoptosis (Z-VAD-FMK). Accordingly, the oxidative-stress-related mechanisms were further assessed. StenB caused subG1 and G2/M accumulation but reduced the G1 phase in TNBC cells, while normal cells remained unchanged between the control and StenB treatments. The apoptosis behavior of TNBC cells was suppressed by StenB, whereas that of normal cells was not suppressed according to an annexin V assay. StenB-modulated apoptosis signaling, such as for caspases 3, 8, and 9, was more significantly activated in TNBC than in normal cells. StenB also caused oxidative stress in TNBC cells but not in normal cells according to a flow cytometry assay monitoring reactive oxygen species, mitochondrial superoxide, and their membrane potential. StenB induced greater DNA damage responses (γH2AX and 8-hydroxy-2-deoxyguanosine) in TNBC than in normal cells. All these StenB responses were alleviated by NAC pretreatment. Collectively, StenB modulated oxidative stress responses, leading to the antiproliferation of TNBC cells with little cytotoxicity in normal cells. [ABSTRACT FROM AUTHOR]

Free sulfide anion (S 2− ) in alkaline media was determined using cathodic stripping voltammetry (CSV) and a graphene oxide-modified screen-printed carbon electrode (SPCE/GO) electrodeposited with Ag, Au, or AuAg nanoparticles (NPs). Electrodeposition was achieved using cyclic voltammetry in dilute sulfuric acid containing AgNO 3 and/or HAuCl 4 ·4H 2 O in which thiourea was essential for stabilizing Ag + . The existence of GO resulted in higher density and more uniform distribution of NPs, compared with those electrodeposited on bare SPCE. The composite electrode SPCE/GO/AgNPs showed the greatest sensitivity but poorest reproducibility. The SPCE/GO/AuNPs, in contrast, showed the best reproducibility with a linear dynamic range of S 2− from 6.25 to 400 μM and no significant interference from various inorganic anions and cations. EDTA, however, was essential to eliminate the interfering effects from metal cations. By co-depositing Au and Ag to form SPCE/GO/AuAgNPs, the sensitivity was significantly improved in contrast to SPCE/GO/AuNPs, and the reproducibility was approximately reserved. By using differential-pulse CSV (DPCSV), a linear dynamic range of 0.05∼1.5 μM was observed. A wider but two-segmented dynamic range, 0.5∼12.5 and 12.5∼312.5 μM, was obtained by using liner-scan CSV (LSCSV). SPCE/GO/AuAgNPs, however, showed a poorer resistance against metal cationic interferents, compared with SPCE/GO/AuNPs, although EDTA was used. This study reveals a facile approach of preparing sensitive modified electrodes for the determination of S 2− in alkaline aqueous media. [ABSTRACT FROM AUTHOR]

Palladium nanoparticles (PdNPs) were prepared via potentiostatic electrolysis using Pt gauze electrode in the room temperature ionic liquid 1-butyl-1-methylpyrrolidinium salicylate (RTIL BMP-SAL) containing PdCl 2 with/without additives of cationic surfactants and PAMAM dendrimer. PdNPs were directly formed and dispersed in the IL during the electrolysis, which was mixed with graphite powder (GP) to prepare the IL–PdNPs–GP composite electrode for the electrochemical oxidation of ethanol in alkaline solutions. Introducing additives into the IL significantly affected the morphology and electrochemical behavior of the PdNPs. A facile approach of metal nanoparticle preparation can be developed based on this study. [ABSTRACT FROM AUTHOR]

Dendrimers are appealing scaffolds for creating carbohydrate mimics with unique multivalent cooperativity. We report here novel bola‐amphiphilic glycodendrimers bearing mannose and glucose terminals, and a hydrophobic thioacetal core responsive to reactive oxygen species. The peculiar bola‐amphiphilic feature enabled stronger binding to lectin compared to conventional amphiphiles. In addition, these dendrimers are able to target mannose receptors and glucose transporters expressed at the surface of cells, thus allowing effective and specific cellular uptake. This highlights their great promise for targeted delivery. [ABSTRACT FROM AUTHOR]

Catalytic nitrite reductions by CuII complexes containing anionic Me2Tp, neutral Me2Tpm, or neutral iPrTIC ligands in the presence of L -ascorbic acid, which served as an electron donor and proton source, were investigated. The results showed that auxiliary ligands are important for copper-mediated catalytic nitrite reduction. Furthermore, the electronic effects of the ligand govern the nitrite reduction efficiency, which should be considered at two control points: one is the susceptibility of the LCuI-nitrite species to protonation and the other is the susceptibility of LCuII to reduction giving LCuI. In addition, an external strong acid leads to the production of nitrous acid, which may suggest that the reactivity of nitrous acid toward the LCuI species is a third control point. [ABSTRACT FROM AUTHOR]

[Display omitted] • SPNC with Cu 2 O/Cu(OH) 2 surface and (1 3 ¯ 2) high-index facet is successfully synthesized. • SPNC shows 31.10 m2 g−1 for surface area and successfully catalyze CO 2 RR. • SPNC shows remarkable selectivity (FE C2H4 = 55.3 %) for the production of C 2 H 4. • Cu 2 O/Cu(OH) 2 surface impact significantly on CO-CO dimer for production of C 2 H 4. In the production of C 2 H 4, a vital raw material in the synthesis of polyethylene and polyvinyl chloride, Cu 2 O is a highly promising catalyst with excellent Faradaic efficiency and selectivity. We propose a method involving the partial reduction of Cu(OH) 2 to Cu 2 O by sodium L-ascorbate for the synthesis of spherical and porous Cu 2 O nanocages (SPNCs) with a surface containing both Cu 2 O and Cu(OH) 2. High-resolution transmission electron microscopy and electron diffraction measurements revealed ∼ 3-nm pores and a (1 3 ¯ 2) high-index facet on the SPNC, respectively. As SPNCs have a porous structure, their specific surface area is greater (31.10 m2 g−1) than that (6.35 m2 g−1) of spherical Cu 2 O nanocrystals (SNCs) with solid interiors. Furthermore, SPNCs, when applied as electrocatalysts for catalysing the CO 2 reduction reaction (CO 2 RR), demonstrated remarkable mass activities (16.92 mA mg−1 at −1.15 V vs. reversible hydrogen electrode) for C 2 H 4 production, with a Faraday efficiency reaching an impressive 55.3 %. Stability test data showed a consistent CO 2 RR current density over 6 h, owing to the porous structure and the presence of both Cu(OH) 2 and Cu 2 O on the catalyst surface. Our proposed SPNC catalysts can be employed as effective CO 2 RR catalysts for producing C 2 H 4 , which may help in reducing the present reliance on petrochemical processes. [ABSTRACT FROM AUTHOR]

β-Diketiminato copper(II) L1CuCl–L4CuCl and their nitrite complexes L1Cu(O2N) and L2Cu(O2N) have been synthesized and characterized. X-ray analysis of the L1CuCl–L4CuCl complexes clearly reveals their mononuclear structure with a four-coordinated Cu(II) center bound by one chloride and three nitrogen atoms of unsymmetrical β-diketiminato ligands. Cyclic voltametric analysis of the Cu(II) complexes shows that the length of the pyridyl arm controls the Cu(II)/Cu(I) redox process. DFT and EPR results confirm that the geometry of the Cu(II) complexes is also controlled by the length of the chelating pyridyl arm. The oxygen atom transfer nitrite reduction of the Cu(II) nitrite complexes leads to the formation of copper(I)–PPh3 and O＝PPh3 which were confirmed by 1H and 31P NMR. The length of the pyridyl arm of the copper(II) nitrite complexes governs the NO-releasing ability. These findings illustrate the important bioinspired behaviour and NO generation from nitrite via oxygen atom transfer of the unsymmetrical β-diketiminato copper(II) complexes as compared to symmetrical β-diketiminato copper(II) complexes. [ABSTRACT FROM AUTHOR]

Prototropic equilibria in ionized DNA play an importantrole incharge transport and radiation damage of DNA and, therefore, continueto attract considerable attention. Although it is well-establishedthat electron attachment will induce an interbase proton transferfrom N1 of guanine (G) to N3 of cytosine (C), the question of whetherthe surrounding water in the major and minor grooves can protonatethe one-electron-reduced G:C base pair still remains open. In thiswork, density functional theory (DFT) calculations were employed toinvestigate the energetics and mechanism for the protonation of theone-electron-reduced G:C base pair by water. Through the calculationsof thermochemical cycles, the protonation free energies were estimatedto be in the range of 11.6–14.2 kcal/mol. The calculationsfor the models of C•–(H2O)8and G(−H1)−(H2O)16, which were used to simulate the detailed processes of protonationby water before and after the interbase proton transfer, respectively,revealed that the protonation proceeds through a concerted doubleproton transfer involving the water molecules in the first and secondhydration shells. Comparing the present results with the rates ofinterbase proton transfer and charge transfer along DNA suggests thatprotonation on the C•–moiety is not competitivewith interbase proton transfer, but the possibility of protonationon the G(−H1)−moiety after interbase protontransfer cannot be excluded. Electronic-excited-state calculationswere also carried out by the time-dependent DFT approach. This informationis valuable for experimental identification in the future. [ABSTRACT FROM AUTHOR]

Abstract: The voltammetric behavior of Pt(II), Fe(II), and mixtures of Pt(II) and Fe(II) was studied in N-butyl-N-methylpyrrolidinium dicyanamide ionic liquid (BMP-DCA IL), N-butyl-N-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide ionic liquid (BMP-TFSI IL), and a mixture of BMP-DCA and BMP-TFSI, respectively. Electrodeposition of PtFe coatings was achieved by controlled-potential electrolysis on tungsten from the aforementioned ILs containing Pt(II) and Fe(II). The Pt(II) species required to prepare these PtFe coatings was introduced into the ILs by addition of PtCl2. In BMP-TFSI, an additional two equivalents of N-butyl-N-methylpyrrolidinium chloride (BMP-Cl) were essential to assist one equivalent of PtCl2 to dissolve. The Fe(II) species was introduced into the ILs by addition of FeCl2 or by anodizing an iron spiral electrode. In BMP-TFSI, additional BMP-Cl had to be added to assist FeCl2 dissolution (FeCl2:BMP-Cl=1:2 (mol:mol)). The PtFe coatings with various atomic ratios of Pt/Fe were studied for their voltammetric behavior towards the oxygen reduction reaction (ORR) in acidic solutions. This study shows that the PtFe alloy coatings with atomic ratios of ∼0.5/0.5 had the highest reductive current density for ORR, better than regular Pt or Pt-electrodeposited electrodes. [ABSTRACT FROM AUTHOR]

Abstract: A series of novel pyrrolo[2,1-c][1,4]benzodiazepine (PBD) hybrids linked with enediyne is described. These compounds were prepared by linking C-8 of DC-81 (1) with an enediyne (10–16) through carbon chain linkers to afford PBD hybrid agents 17–23 in good yields. Most of the hybrids on human cancer cell lines exhibited higher cytotoxicity, and an increase in the sub-G1 population than 1. In a previous article, we have demonstrated that DC-81-indole conjugate agents (3–6) are potent inducers of cell apoptosis in melanoma. In the present article, we investigated whether DC-81-enediyne agents possess more cytotoxicity than 6 on human 293T cells. Our data revealed that treatment of 293T cells with DC-81-enediyne resulted in a significant increase of annexin V binding, caspase-3 degradation, and p53 arrest to identify apoptotic cells than 6. These results suggest that the DC-81-enediyne agents are more efficient in inducing apoptosis than DC-81-indole in 293T cells. [Copyright &y& Elsevier]

Photoactivatable ligation auxiliaries present an attractive approach for expanding the applicability of native chemical ligation (NCL). In contrast to thiol-based mercaptobenzyl-type ligation scaffolds, photoactivatable auxiliaries are cleaved after ligation by photolysis, thereby simplifying protein assembly in non-cysteine NCL and causing minimal perturbation to the native polypeptide chains. This study reports an easy-to-attach 1-[5-(thiomethyl)-2-nitrophenyl]ethyl-(TmNpE)-auxiliary at the internal aspartic/glutamic acid side-chain of the N -terminal peptide fragments. This auxiliary enables a long-range NCL and allows for photolytic removal in an aqueous buffer without a reagent. The versatility of the method was highlighted by the synthesis of a human programmed cell death-ligand 1 (hPD-L1) peptide inhibitor, Ar5Y-3. The TmNpE group offers easy introduction, compatibility with peptide ligation reactions, and mild cleavage conditions, which may be beneficial for peptides or protein synthesis other than cysteine ligation sites. [Display omitted] [ABSTRACT FROM AUTHOR]

The selective and efficient nitrite reduction process is ubiquitous in biological systems. To understand copper-mediated nitrite reduction, we developed a bio-inspired model system to investigate the mechanism of copper-containing nitrite reductase. A well-characterized copper(i)-nitrate complex with amino functionalized 2-(diphenylphosphino)aniline ligands, [(Ph2PC6H4(o-NH2))2Cu(ONO)], demonstrated the aniline protonation will cause NO release in an acidic environment. To further understand NO releasing ability, we also performed pH-dependency experiments and confocal imaging to release NO under physiological buffer conditions. According to titration and spectroscopic studies on the protonation reaction of complex [(Ph2PC6H4(o-NH2))2Cu(ONO)], we proposed a mechanistic pathway for proton transfer and NO release. Furthermore, DFT calculations predicted that the release of NO takes place via aniline in both organic and aqueous media. These results highlight the importance of the proton-rich microenvironment around the copper(i)-nitrite core to induce nitrate reduction in a chemical and biological environment. [ABSTRACT FROM AUTHOR]

Selective glucose binding was identified through five generations of monoboronic acid-functionalized PAMAM dendrimers. The best selectivity obtained when using G3 dendrimers (1b) generated 71.1, 94.9, and 1309 times stronger binding than when using galactose, fructose, and lactose, respectively. Further experiments using dendrimer analogues and glucose derivatives suggested that two nearby monoboronic acids cooperatively bound one glucose. [ABSTRACT FROM AUTHOR]

Two copper(i)–nitro complexes [Tpm3-tBuCu(NO2)] (1) and [(Ph3P)2N][Tp3-tBuCu(NO2)] (2), containing steric bulky neutral tris(3-tert-butylpyrazolyl)methane and anionic hydrotris(3-tert-butylpyrazolyl)borate ligands, have been synthesized and characterized. Complex 2 adopts a unique κ2-binding mode of Tp3-tBu around the copper(i)–nitro environment in the solid state and shows a four-coordinated tetrahedral geometry surrounded by a nitro and three pz3-tBu groups in solution. Both complexes 1 and 2 allow for the stoichiometric reduction of NO2− to NO with H+ addition. The results of this effort show that increasing steric bulk and electron donation properties on the nitrogen ancillary ligand will improve the nitrite reduction ability of the copper(i)–nitro model complexes. [ABSTRACT FROM AUTHOR]

The preparation of boronic acid containing dendrimers is still a difficult task in dendrimer chemistry. In this investigation, an unanticipated hydrolysis product ( 4) was identified during the preparation of (G:2)-PAMAM- dendri-(4-phenyl boronic acid)14 ( 3) by acquiring its 1H NMR, 13C NMR, and UV-vis absorption spectra and IR spectra and comparing them with those of 4-hydroxylbenzoic acid ( 5). Furthermore, an Alizarin Red S staining analysis, ICP-MS, and 11B NMR spectrum indicated the lack of boronic acid in 4. Finally, treatment of 3 with hydrogen peroxide gave a product that was determined to be identical to dendrimer 4. By analyzing the formation of 4 under various conditions, the presence of numerous primary amines in a PAMAM dendrimer did accelerate the hydrolysis of peripheral boronic acid. This investigation revealed an apparent intrinsic problem that needs to be overcome during the preparation of boronic acid containing dendrimers and related boronic acid containing macromolecules. [ABSTRACT FROM AUTHOR]

Despite recent advances in modern medicine, castration-resistant prostate cancer remains an incurable disease. Subpopulations of prostate cancer cells develop castration-resistance by obtaining the complete steroidogenic ability to synthesize androgens from cholesterol. Statin derivatives, such as simvastatin, inhibit cholesterol biosynthesis and may reduce prostate cancer incidence as well as progression to advanced, metastatic phenotype. In this study, we demonstrate novel simvastatin-related molecules SVA, AM1, and AM2 suppress the tumorigenicity of prostate cancer cell lines including androgen receptor-positive LNCaP C-81 and VCaP as well as androgen receptor-negative PC-3 and DU145. This is achieved through inhibition of cell proliferation, colony formation, and migration as well as induction of S-phase cell-cycle arrest and apoptosis. While the compounds effectively block androgen receptor signaling, their mechanism of inhibition also includes suppression of the AKT pathway, in part, through disruption of the plasma membrane. SVA also possess an added effect on cell growth inhibition when combined with docetaxel. In summary, of the compounds studied, SVA is the most potent inhibitor of prostate cancer cell tumorigenicity, demonstrating its potential as a promising therapeutic agent for castration-resistant prostate cancer. [ABSTRACT FROM AUTHOR]

Spherical dendrimer structures cannot be structurally modeled using conventional polymer models of random coil or rod-like configurations during the calibration of the static light scattering (LS) detectors used to determine the molecular weight (M.W.) of a dendrimer or directly assess the purity of a synthetic compound. In this paper, we used the Debye equation-based scaling relation, which predicts that the static LS intensity per unit concentration is linearly proportional to the M.W. of a synthetic dendrimer in a dilute solution, as a tool to examine the purity of high-generational compounds and to monitor the progress of dendrimer preparations. Without using expensive equipment, such as nuclear magnetic resonance or mass spectrometry, this method only required an affordable flow injection set-up with an LS detector. Solutions of the purified dendrimers, including the poly(amidoamine) (PAMAM) dendrimer and its fourth to seventh generation pyridine derivatives with size range of 5-9 nm, were used to establish the scaling relation with high linearity. The use of artificially impure mixtures of six or seven generations revealed significant deviations from linearity. The raw synthesized products of the pyridine-modified PAMAM dendrimer, which included incompletely reacted dendrimers, were also examined to gauge the reaction progress. As a reaction toward a particular generational derivative of the PAMAM dendrimers proceeded over time, deviations from the linear scaling relation decreased. The difference between the polydispersity index of the incompletely converted products and that of the pure compounds was only about 0.01. The use of the Debye equation-based scaling relation, therefore, is much more useful than the polydispersity index for monitoring conversion processes toward an indicated functionality number in a given preparation. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this study, a new non-heme iron complex was prepared by mixing FeCl 3 ∙6H 2 O and 2,4,6-tris(2-pyridylmethylamino)-1,3,5-triazine (TPMATA) in ionic liquid 1-butyl-1-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)amide (IL [BMP + ][TFSA − ]). The iron complex (TPMATA-FeCl 3 ) was used as a modifier for preparing the TPMATA-FeCl 3 -modified carbon ionic liquid electrode (TPMATA-FeCl 3 /CILE). H 2 O 2 was electrocatalytically reduced at the TPMATA-FeCl 3 /CILE in neutral aqueous solutions via Fenton's mechanism in which hydroxyl radical, •OH, was produced, and the radical was detected by using a fluorescence probe. This electrode showed a sensitivity of 22.1 μA∙mM −1 and a dynamic range of 0.025∼4.69 mM with a regression coefficient R 2 of 0.993 (or 0.025∼0.765 mM, R 2 = 0.997, sensitivity = 27.6 μA∙mM −1 ). The detection limit was 0.0125 mM (S/N = 3). This electrode shows the potential to be used as an electrochemical H 2 O 2 sensor or for the production of hydroxyl radicals. [ABSTRACT FROM AUTHOR]

Generation-dependent cooperation was observed in the reduction of molecular oxygen by a series of Cu2+ complexes of pyridine-modified polyamidoamine (PAMAM) dendrimers. The cooperative behavior of the metal ions was examined by preparing (G2-G6)- dendri-PAMAM-(Py) n and testing the dendrimers for their ability to reduce oxygen catalytically in the presence of several Cu2+ ion concentrations. Spectrophotometric measurements during the reactive metallic ion titrations revealed that the maximum numbers of reactive Cu2+ ions available for O2 reduction were 4.8, 7.6, 22.2, 57.3, and 81.7 in each of the second- to sixth-generation (G2-G6) dendrimer complexes, respectively. An analysis revealed that each Cu2+ ion worked independently as an active center in the G2 to G4 dendrimer complexes. By contrast, pairs of Cu2+ ion active species were present in the G5 and G6 dendrimer complexes. A kojic acid titration indicated that the copper ions were proximal and formed a bicopper active center in the G5 and G6 dendrimer complexes. Catalytic reactions with catechol as a reducing agent further demonstrated the activity of the dinuclear copper center in the G5 and G6 dendrimer complexes. The present findings suggest that generations of dendrimer-metal complexes can alter their catalytic behavior. [ABSTRACT FROM AUTHOR]

The benchmark study of DFT methodson the activation energies ofphosphodiester C3′–O and C5′–O bond rupturesand glycosidic C1′–N bond ruptures induced by electronattachment was performed. While conventional pure and hybrid functionalsprovide a relatively reasonable description for the C1′–Nbond rupture, they significantly underestimate the energy barriersof the C–O bond ruptures. This is because the transition statesof the later reactions, which are characterized by an electron distributiondelocalized from the nucleobase to sugar–phosphate backbone,suffer from a severe self-interaction error in common DFT methods.CAM-B3LYP, M06-2X, and ωB97XD are the top three methods thatemerged from the benchmark study; the mean absolute errors relativeto the CCSD(T) values are 1.7, 1.9, and 2.2 kcal/mol, respectively.The C–O bond cleavages of 3′- and 5′-dXMP•–, where X represents four nucleobases, werethen recalculated at the M06-2X/6-31++G**//M06-2X/6-31+G* level, andit turned out that the C–O bond cleavages do not proceed aseasily as previously predicted by the B3LYP calculations. Our calculationsrevealed that the C–O bonds of purine nucleotides are moresusceptible than pyrimidine nucleotides to the electron attachment.The energies of electron attachment to nucleotides were calculatedand discussed as well. [ABSTRACT FROM AUTHOR]

Triazine dendrimers terminated with either four or eight dichlorotriazines can be prepared in high yields by reacting an amine-terminated dendrimer with cyanuric chloride. These materials exist as white powders and are stable to storage at room temperature. Sequential nucleophilic aromatic substitution with two different amine nucleophiles yields compounds that display the desired compositional diversity. Reaction conditions for the substitution were developed using a model dichlorotriazine with amine nucleophiles at −20, 0, and 25 °C. Selective substitution is favored at lower temperatures and with more nucleophilic amine groups. [ABSTRACT FROM AUTHOR]

Abstract: Two pentanuclear copper(I) thiolato clusters of the formula [Cu5(L)3]− (L = pyridine-2,6-dimethanethiolate (L1), (1); 4-methylpyridine-2,6-dimethanethiolate (L2), (2)) were synthesized utilizing a single-step procedure, and their structures were characterized by X-ray crystallography. The aforementioned pentanuclear complexes possess an interesting propeller-like Cu5S6 core where all Cu centers are three-coordinate. Electrospray ionization mass spectrometry (ESI-MS) investigation of the pentanuclear copper(I) thiolato clusters with added hetero-ligands demonstrated interesting ligand exchange behavior. The product distribution resulting from ligand exchange not only depended on the quantity of added ligand, but also was sensitive to the coordination ability of the ligand. The ESI-MS method used in this study can serve as a useful tool for probing exchange behavior in coordination metal complexes that cannot otherwise be determined by NMR. [Copyright &y& Elsevier]

The hydrophobic ionic liquid N-butyl- N-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)amide (BMP-TFSA IL), which contains a series of flexible ionophores of polypyridine-type small molecules or two rigid ionophores of peripherally pyridine-modified PAMAM dendrimers, was used to extract cupric ions from aqueous solutions. The polypyridine-type ionophores show good selectivity toward cupric ions at pH 2. The selectivity is affected by the spacing between the two amino groups. However, the pyridine-modified dendrimers showed poor selectivity, although their extraction efficiency still depended on the pH of the aqueous solution. The ionic liquids that contained small molecular ionophores and their dendrimer analogs were reused after acid washing or electrochemical reduction. During acid washing, the nitrogen atoms of the ionophores were protonated to release the cupric ions into the aqueous phase, and the copper atoms were deposited onto the electrode surface during the electrochemical reduction accompanied by the regeneration of the ionophores. [ABSTRACT FROM AUTHOR]

Abstract: A facile and effective synthesis for a wide variety of 4-arylidene-5-imidazolinone derivatives was developed. 4-Arylidene-5-oxazolinones were prepared by Erlenmeyer azlactone synthesis from N-acylglycines and arylaldehydes. The ring-opening reactions of the 4-arylidene-5-oxazolinones with primary amines afforded 2-acylamino-3-arylacrylamides in excellent yields. A new dehydrative cyclization of the 2-acylamino-3-arylacrylamides in pyridine under reflux furnished the corresponding 4-arylidene-5-imidazolinones in good yields. [Copyright &y& Elsevier]

Abstract: A number of 6-aryl-11-iminoindeno[1,2-c]quinoline derivatives were synthesized and evaluated for their antiproliferative activities. Among them, (E)-6-{4-[3-(dimethylamino)propoxy]phenyl}-2-fluoro-9-hydroxy-11H-indeno[1,2-c]quinolin-11-one O-3-(dimethylamino)propyl oxime (23a) was the most active, exhibited GI50 values of 0.64, 0.39, 0.55, 0.67, and 0.65μM against the growth of Hep G2, Hep 3B, A549, H1299, and MDA-MB-231, respectively. Compound 23a inhibited the growth of hepatoma cell lines in a dose- and time-dependent manner. The proportion of cells was decreased in the G1 and accumulated in G2/M phase after 12h treatment of 23a, while the hypodiploid (sub-G0/G1 phase) cells increased. Further investigations have shown that 23a induced cell cycle arrest at G2/M phase and induce apoptosis via activation of p53, Bax, and caspase-8 which consequently cause cell death. [Copyright &y& Elsevier]

Abstract: A mild, efficient, and regioselective carbanion–yne intramolecular cyclization mediated by t-BuOK for the synthesis of 2-substituted 3-benzylbenzofurans is developed. It was started from o-iodophenol (1), based on O-alkylation, and the Sonogashira reaction in sequence to produce 2-(2-phenylethynylphenoxy)-1-arylalkanones (5). An intramolecular carbanion–yne 5-exo-dig cyclization reaction of 5, which was mediated by t-BuOK, yielded title benzofurans in good yields. [Copyright &y& Elsevier]

In this study, we have developed two new l-tryptophan based contrast agents [Gd(Try-TTDA)(H2O)]2−and [Gd(Try-ac-DOTA)(H2O)]−. Upon addition of Cu(ii) to [Gd(Try-TTDA)(H2O)]2−, significant increases in the relaxivity (r1) and hydration number of [Gd(Try-TTDA)(H2O)]2−were observed. However, it only induced a minute increase in the relaxivity (r1) in the case of [Gd(Try-ac-DOTA)(H2O)]−. Furthermore, the interaction of Cu(ii) with the indole ring of Gd(iii) complexes was explored by measuring the intrinsic fluorescence of the tryptophan of the Gd(iii) complex. With the addition of one equivalent of Cu(ii) to [Gd(Try-TTDA)(H2O)]2−the indole fluorescence was completely quenched. Moreover, the [Gd(Try-TTDA)(H2O)]2−complex shows excellent selectivity towards Cu(ii) over other metal ions (Cu(ii) > La(iii) > Mg(ii)). Importantly, the significant signal intensity (2073 ± 67) for in vitroMR imaging using [Gd(Try-TTDA)(H2O)]2−in the presence of Cu(ii) implicates that this new smart contrast agent ([Gd(Try-TTDA)(H2O)]2−) can serve as a Cu(ii) sensor for MR imaging. [ABSTRACT FROM AUTHOR]

Abstract: A series of 11-alkoxylated and 11-aminated benzofuro[2,3-b]quinoline derivatives were designed, synthesized, and evaluated for their anti-TB and cytotoxic activities. The known 11-chlorobenzofuro[2,3-b]quinoline (3) was synthesized in a single step from anthranilic acid and 2-coumaranone in phosphorus oxychloride in 51% yield for the first time. Treatment of 3 with alcohols and amines gave 11-alkoxylated and 11-aminated benzofuro[2,3-b]quinoline derivatives respectively, which were evaluated for their anti-TB and cytotoxic activities. Our results indicated that 11-arylaminated derivatives were more active than their respective 11-aryloxylated isosteric isomers against Mycobacterium tuberculosis. Among the tested compounds, 11-methoxybenzofuro[2,3-b]quinoline (4), 11-methylamino- benzofuro[2,3-b]quinoline (9), and 11-dimethylaminobenzofuro[2,3-b]quinoline (14) exhibited significant activities against the growth of M. tuberculosis (MIC values of <0.20μg/mL) and low cytotoxicities against VERO cell with IC50 values of 11.77, 5.55, and >30.00μg/mL respectively. The selectivity index (SI=IC50/MIC) for 4, 9, and 14 was greater than 58.85, 27.75, and 150 respectively. [Copyright &y& Elsevier]

Abstract: A convenient salt-free approach to the halodecarboxylation of cinnamic acid analogs to β-bromostyrene was reported. This conversion was conducted at 0°C in CH2Cl2 with only 10% of acetic acid. This protocol can be used for cinnamic acids with a variety of substituents, including β-methyl cinnamic acid (1d) in 60–81% yield, but not for hydroxyl- and p-methyl-cinnamic acids. Meanwhile, pyridine hydrobromide perbromide was used as bromide source to convert 1a–2a in 59% yield. [Copyright &y& Elsevier]

Three Ru(II)-DMSO complexes (1-3) containing 2-(3-pyrazolyl)pyridine (PzPy), 2-pyrazol-3-ylfuran (PzO), or 2-pyrazol-3-ylthiophene (PzS) ligand, were synthesized and characterized. The monodentate coordination of the heterocyclic pyrazolyl ligand (PzPy) with Ru(II) ion via N atom was confirmed by single crystal X-ray diffraction. Complex 1 could be converted to the known η 2-bidentate PzPy complex cis (Cl), cis (S)-[RuCl 2 (PzPy)(DMSO) 2 ] (4) under reflux conditions. The mechanism underlying binding mode transformation was studied by 1H NMR spectroscopy and density functional theory (DFT) calculations. The binding abilities of the complexes (1 – 4) with calf-thymus (CT) DNA and bovine serum albumin (BSA) were investigated using spectroscopic and molecular docking techniques. Among the four Ru(II) complexes, complexes 1 and 3 inhibited the long-term proliferation of human breast cancer cells, whereas complexes 2 and 4 did not inhibit their proliferation to a considerable extent. Interestingly, complexes 1 and 3 did not induce significant cell death but rather attenuated the clonogenicity of breast cancer cells by upregulating reactive oxygen species (ROS), endoplasmic reticulum (ER) and autophagic stress. Distorted octahedral heterocyclic pyrazolyl appended Ru(II)-DMSO complexes have been synthesized and characterized. Binding mode transformation has been confirmed by spectroscopy and theoretical studies. Complexes showed good binding ability towards biomolecules, which inhibit clonogenicity rather than causing the death of breast cancer cells. [Display omitted] • Three Ru(II)-DMSO complexes with pyrazolyl ligands were synthesized. • Ru(II)-DMSO complexes characterized by crystallographic and spectroscopic tools. • The mechanism for the monodentate to bidentate was investigated. • Complexes exhibited appreciable binding efficacy with biomolecules. • One of the Ru(II)-DMSO complexes exhibited good activity against breast cancer cells. [ABSTRACT FROM AUTHOR]

A new 2,4,6-triisocyanomesitylene ligand was synthesized to prepare unique N -aryl- N′ -alkylpyridyl β-diketiminato copper(I) complexes. The FT-IR spectroscopic analysis of the prepared copper(I) isocyanide complexes show the CN stretching frequencies experience a significant red shift relative to those of the free ligands, indicating that π-back bonding interaction exist between copper(I) centers and isocyanide moieties. • New tiisocyanide was synthesized and characterized by X-ray differraction. • Dinuclear and trinuclear copper isocyanide complexes were carried out to elucidate their structural features. • di- and tri-isocyanide ligands show lower LUMO energy than monoisocyanide by DFT analysis. A new 2,4,6-triisocyanomesitylene ligand was synthesized and along with 1,4-isocyanobenzene utilized to prepare unique N -aryl- N′ -alkylpyridyl β-diketiminato copper(I) complexes. Crystallographic characterization of 2,4,6-triisocyanomesitylene, dinuclear and trinuclear copper isocyanide complexes were carried out to elucidate their structural features. The FT-IR spectroscopic analysis of the prepared copper(I) isocyanide complexes show the CN stretching frequencies experience a significant red shift relative to those of the free ligands, indicating that π-back bonding interaction exist between copper(I) centers and isocyanide moieties. DFT based frontier molecular orbital analysis demonstrated that the enhanced π-back bonding is a consequence of the π-accepting abilities of the 1,4-diisocyanobenzene and 2,4,6-triisocyanomesitylene ligands. [ABSTRACT FROM AUTHOR]

A concise solid-phase synthesis of inverse poly(amidoamine) dendrons was developed. Upon introduction of AB2-type monomers, each dendron generation was constructed via one reaction. G2 to G5 dendrons were constructed in a peptide synthesizer in 93%, 89%, 82%, and 78% yields, respectively, within 5 days. [ABSTRACT FROM AUTHOR]

A correction to the article "Cooperative Effects in Copper Polyamidoamine Dendrimer Complexes Catalyzing the Reduction of Molecular Oxygen," that was published in the 2015 issue is presented.

Deoxy and amino sugars are often constituents of secondary metabolites, many of which are of clinical importance. These unusual sugars are attached through 0-, N-, or C- linkages to their respective aglycons and commonly play essential roles in determining the biological activities of the parent compounds. Altering the composition of sugar appendages in glycoconjugates holds promise for creating new products with novel biological activities. Hence, efforts to develop effective glycosylation strategies have been vigorously pursued by scientists for decades. Significant progress has been made recently using genetic and biochemical methods to perform glycosylation in vivo. For example, the feasibility of reengineering sugar biosynthetic machineries to generate diverse sugar structures and to incorporate foreign glycosyltransferase genes into appropriate strains to facilitate coupling between various sugar donors and aglycon acceptors in a combinatorial manner has been demonstrated.

A new dehydrative cyclization method for the synthesis of the title compounds is developed for a broad scope of numerous commercially available starting compounds. [ABSTRACT FROM AUTHOR]

Two synthetic routes for the preparation of 2-aroyl- and 2-alkyl-3-benzylbenzofurans are developed. [ABSTRACT FROM AUTHOR]