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A convenient and highly efficient palladium-catalyzed reaction of [60]fullerene (C60) with aroyl compounds via enolate-mediated C-H activation and hydroxylation has been exploited for the first time to synthesize novel C60-fused dihydrofurans, and rare 1,4-fullerenols. Further functionalization including etherification, and esterification of synthesized 1,4-fullerenols provided efficient access to versatile fullerene derivatives. Moreover, a plausible reaction mechanism leading to the observed products is proposed. [ABSTRACT FROM AUTHOR]

Chlorinated paraffins (CPs) are a class of compounds that are currently produced and used in large amounts in commercial products worldwide. In this study, food, indoor air, indoor dust, and drinking water samples were collected to evaluate the external exposure levels of CPs and possible pathway for the general population in Beijing, China. Short chain CPs (SCCPs) and medium chain CPs (MCCPs) in 199 samples were analyzed using a gas chromatography tandem time-of-flight high-resolution mass spectrometry (GC-TOF-HR-MS) method. High levels of CPs were observed in the indoor environment from residential houses, offices, and student dormitories. The geometric mean concentrations (GM) of ∑SCCPs and ∑MCCPs in indoor dust were 92 μg g-1 and 82 μg g-1, respectively, while in indoor air, the concentrations were 80 ng m-3 and 3.4 ng m-3, respectively. The GM of ∑SCCPs and ∑MCCPs in the diet were 83 ng g-1 dry weight (dw) and 56 ng g-1 dw, respectively. The most important external exposure routes to CPs to the general populations in Beijing were food intake and indoor dust ingestion. Indoor dust and indoor air posed higher risks for toddlers and infants than for adults. [ABSTRACT FROM AUTHOR]

Crystal growth from amorphous drugs is of interest in the context of solubility enhancing formulations. Herein, the impact of polymers on the crystal growth of different polymorphs from the undercooled liquid was investigated using indomethacin (IDM) as a model compound and hydroxypropyl methylcellulose (HPMC), hydroxypropyl methylcellulose acetate succinate (HPMCAS), and polyvinylpyrrolidone (PVP) as polymeric inhibitors. Samples sandwiched between two coverslips were prepared by melt quenching, and polymorphs were identified using Raman spectroscopy, hot stage microscopy, and X-ray diffraction. Crystal growth rates of δ, α, and γ polymorphs were measured in the absence and presence of polymers. Polymorphs grown from pure IDM melt showed different crystal growth rates at a given temperature, that persisted when differences in the extent of undercooling were accounted for. The crystal growth rates of IDM crystals were reduced by the three polymers. At lower temperatures, the effectiveness of the polymers in inhibiting crystal growth decreased in the order of PVP > HPMC > HPMCAS. Interestingly, it was found that the same polymer had different inhibitory effects on the crystal growth of different polymorphs, with polymers being least effective in inhibiting the growth of the γ polymorph. Clearly the impact of polymers on crystal growth from undercooled melts is highly complex, depending not only on the properties of the liquid phase, but also on the growing crystal polymorph. [ABSTRACT FROM AUTHOR]

Pristine high-altitude mountains are ideal areas for studying the potential mechanism behind the long-range transport and environmental behavior of persistent organic pollutants in remote areas. Short chain chlorinated paraffins (SCCPs) are the most complex halogenated contaminants in the environment, and have attracted extensive worldwide interest in recent years. In this study, the spatiotemporal concentrations and distributions of SCCPs in air collected from Shergyla Mountain (located in the southeast of the Tibetan Plateau) and Lhasa were investigated during 2012-2015. Generally, the total SCCP levels at Shergyla Mountain and Lhasa were between 130 and 1300 pg/m³ and 1100-14440 pg/m³, respectively. C10 and C11 components were the most abundant homologue groups, indicating that lighter SCCP homologue groups are capable of relatively long-range atmospheric transport. Relatively high but insignificant atmospheric SCCP concentrations at Shergyla Mountain area and Lhasa were observed from 2013 to 2015 compared with 2012. At Shergyla Mountain, SCCP concentrations on the eastern and western slopes increased with altitude, implying that "mountain cold-trapping" might occur for SCCPs. A back-trajectory model showed that SCCP sources at Shergyla Mountain and Lhasa were primarily influenced by the tropical monsoon from Southwest and South Asia. [ABSTRACT FROM AUTHOR]

An efficient and simple copper-mediated oxidative coupling of N,N-dimyethylanilines with [60]fullerene was employed to obtain a high yield of scarce 6-membered-ring [60]fullerene-fused tetrahydroquinolines. The reaction occurred through sp³ C-H bond activation under mild reaction conditions with molecular oxygen as the oxidant. A plausible reaction pathway was proposed, and the electrochemistry of the fullerene products was investigated. [ABSTRACT FROM AUTHOR]

Pd(0)-catalyzed intramolecular C-H alkenylation was achieved with excellent yields and enantioselectivity for the construction of planar chiral ferrocenes. It is compatible with a broad range of substrates and various functional groups. Notably, the enantioselective and diastereoselective synthesis of planar chiral ferrocenes was realized by cascade C-H arylation and alkenylation reaction for the first time. Additionally, the product was easily converted into a N,O-bidentate ligand, showing promising chiral induction in asymmetric alkynylation of 1-naphthaldehyde. [ABSTRACT FROM AUTHOR]

A Pd-catalyzed, asymmetric oxidative cross-coupling reaction between ferrocenes and heteroarenes is described. The process, which takes place via a twofold C-H bond activation pathway, proceeds with modest to high efficiencies (36-86%) and high levels of regio- and enantioselectivity (95-99% ee). In the reaction, air oxygen serves as a green oxidant and excess amounts of the coupling partners are not required. The process is the first example of a catalytic asymmetric biaryl coupling reaction that occurs via double C-H bond activation. Finally, the generated coupling products can be readily transformed into chiral ligands and catalysts. [ABSTRACT FROM AUTHOR]

The characterization of nanomaterials under high strain rates is critical to understand their suitability for dynamic applications such as nanoresonators and nanoswitches. It is also of great theoretical importance to explore nanomechanics with dynamic and rate effects. Here, we report in situ scanning electron microscope (SEM) tensile testing of bicrystalline silver nanowires at strain rates up to 2/s, which is 2 orders of magnitude higher than previously reported in the literature. The experiments are enabled by a microelectromechanical system (MEMS) with fast response time. It was identified that the nanowire plastic deformation has a small activation volume (<10b³), suggesting dislocation nucleation as the rate controlling mechanism. Also, a remarkable brittle-to-ductile failure mode transition was observed at a threshold strain rate of 0.2/s. Transmission electron microscopy (TEM) revealed that along the nanowire, dislocation density and spatial distribution of plastic regions increase with increasing strain rate. Furthermore, molecular dynamic (MD) simulations show that deformation mechanisms such as grain boundary migration and dislocation interactions are responsible for such ductility. Finally, the MD and experimental results were interpreted using dislocation nucleation theory. The predicted yield stress values are in agreement with the experimental results for strain rates above 0.2/s when ductility is pronounced. At low strain rates, random imperfections on the nanowire surface trigger localized plasticity, leading to a brittle-like failure. [ABSTRACT FROM AUTHOR]

A highlyefficient synthesis of planar chiral ferrocenylpyridinederivatives via Pd-catalyzed intramolecular C–H arylation wasdeveloped, and quantitative yields and excellent enantioselectivitywere obtained for a wide range of substrates. Notably, the catalystloading could be lowered to 0.2 mol %, which represents the highestcatalytic efficiency found for asymmetric C–H bond activation(TON up to 495). These compounds could be easily transformed to pyridine N-oxides, displaying promising catalytic reactivity in the asymmetric opening of meso-epoxide. Moreover, computational investigations wereconducted to clarify the origin of the excellent enantioselectivity.The compatibility of large-scale synthesis and low catalyst loadingshould enhance the practicality of the synthetic application of thecurrent method. [ABSTRACT FROM AUTHOR]

A highly efficient synthesis of planar chiral ferrocenes by enantioselective Pd(0)-catalyzed direct C–H arylation from readily available starting materials under mild reaction conditions was developed (up to 99% yield, 99% ee). The products can be easily transformed to the highly efficient planar ferrocene ligands, which have demonstrated high efficiency in Pd-catalyzed asymmetric allylic alkylation and amination reactions. [ABSTRACT FROM AUTHOR]

Organized self-assemblies of Janus catalytic motors, induced by hydrophobic surface interactions involving multiple motor/motor and motor/nonmotor particles, display controlled coordinated self-propulsion. The influence of the self-assembled structures upon the motion behavior is investigated. A dynamic 'on-the-fly' assembly is observed during the continuous movement of the individual components, along with changes in the motion behavior. Organized assemblies of multiple motor/nonmotor particles are also illustrated toward optimal cargo transport and delivery. Such controlled structures and motion of chemically powered Janus micromotor assemblies hold considerable promise for the creation of intelligent nanomachines that perform collective tasks. [ABSTRACT FROM AUTHOR]

Enantioselective Pd(II)-catalyzed direct coupling of aminomethylferrocene derivatives with boronic acids was realized. With commercially available Boc-l-Val-OH as a ligand, planar-chiral ferrocenes could be synthesized in yields of 14-81% with up to 99% ee under mild conditions. [ABSTRACT FROM AUTHOR]

Tubular polyaniline (PANI)/Zn micro-rockets are described that display effective autonomous motion in extreme acidic environments, without any additional chemical fuel. These acid-driven hydrogen-bubble-propelled microrockets have been electrosynthesized using the conical polycarbonate template. The effective propulsion in acidic media reflects the continuous thrust of hydrogen bubbles generated by the spontaneous redox reaction occurring at the inner Zn surface. The propulsion characteristics of PANI/Zn microrockets in different acids and in human serum are described. The observed speed-pH dependence holds promise for sensitive pH measurements in extreme acidic environments. The new microrockets display an ultrafast propulsion (as high as 100 body lengths/s) along with attractive capabilities including guided movement and directed cargo transport. Such acid-driven microtubular rockets offer considerable potential for diverse biomedical and industrial applications. [ABSTRACT FROM AUTHOR]

As the active site mimics of [FeFe]-hydrogenases, 14 new butterfly [2Fe2E] (E = Se, S) cluster complexes have been prepared by various synthetic routes. The N-substituted single-butterfly [2Fe2Se] complexes [(μ-SeCH2)2NC(O)R]Fe2(CO)6(1, R = Me; 2, R = Ph; 3, R = PhCH2O) were prepared by reactions of the in situ formed (μ-LiSe)2Fe2(CO)6with RC(O)N(CH2Cl)2, whereas the corresponding [2Fe2S] complexes [(μ-SCH2)2NC6H4R-p]Fe2(CO)6(4, R = CO2Et; 5, R = CH2OH) were produced by reaction of the in situ generated (μ-HS)2Fe2(CO)6with aqueous CH2O followed by treatment with p-RC6H4NH2. The parent single-butterfly [2Fe2Se] complex [(μ-SeCH2)2NH]Fe2(CO)6(6) could be prepared by reaction of the N-substituted complex 3with deprotecting reagent BBr3, BF3·OEt2/EtSH, or BF3·OEt2/Me2S, whereas the N-substituted single-butterfly [2Fe2Se] complexes [(μ-SeCH2)2NC(O)R]Fe2(CO)6(7, R = Et; 8, R = PhCH2) were produced by reactions of 6with acylating agents RC(O)Cl in the presence of Et3N. While the known parent single-butterfly [2Fe2S] complex [(μ-SCH2)2NH]Fe2(CO)6reacted with 2,6-[ClC(O)]2C5H3N to afford double-butterfly [2Fe2S] complex [Fe2(CO)6(μ-SCH2)2NC(O)]2(2,6-C5H3N) (9), the new N-hydroxyethyl-substituted single-butterfly [2Fe2Se] complex [(μ-SeCH2)2N(CH2)2OH]Fe2(CO)6(10) could be obtained by the in situ reaction of (μ-HSe)2Fe2(CO)6with (HOCH2)2N(CH2)2OH. Interestingly, complex 10could react with [ClC(O)]2CH2or 1,3,5-[ClC(O)]3C6H3in the presence of Et3N to give the corresponding double-butterfly [2Fe2Se] complex [Fe2(CO)6(μ-SeCH2)2N(CH2)2O2C]2CH2(11) and triple-butterfly complex [Fe2(CO)6(μ-SeCH2)2N(CH2)2O2C]3(1,3,5-C6H3) (12), whereas the known single-butterfly [2Fe2S] complex [(μ-SCH2)2N(CH2)2OH]Fe2(CO)6could react with 2,6-[ClC(O)]2C5H3N and 1,3,5-[ClC(O)]3C6H3in the presence of Et3N to afford the corresponding double-butterfly [2Fe2S] complex [Fe2(CO)6(μ-SCH2)2N(CH2)2O2C]2(2,6-C5H3N) (13) and triple-butterfly complex [Fe2(CO)6(μ-SCH2)2N(CH2)2O2C]3(1,3,5-C6H3) (14), respectively. All the new complexes 1–14have been characterized by elemental analysis and spectroscopy, as well as by X-ray crystallography for 1–4, 7–9, and 14. In addition, the electrochemical study indicated that complexes 1and 2can catalyze the proton reduction of HOAc to give hydrogen. [ABSTRACT FROM AUTHOR]

Reactions of 2,6-(ArNCH)2C6H3Li with CrCl2(THF)2afford two trinuclear bis(imino)aryl NCN pincer Cr(II) complexes {[2,6-(ArNCH)2C6H3]Cr(μ-Cl)2}2Cr [Ar = 2,6-Me2C6H3(1a), 2,6-Et2C6H3(1b)], and a mononuclear bis(imino)aryl NCN pincer Cr(II) complex [2,6-(ArNCH)2C6H3]Cr(μ-Cl)2Li(THF)2[Ar = 2,6-iPr2C6H3(1c)], respectively. Similar reactions of 2,6-(ArNCH)2C6H3Li with CrCl3(THF)3produce only mononuclear bis(imino)aryl NCN pincer Cr(III) complexes [2,6-(ArNCH)2C6H3]CrCl2(THF) [Ar = 2,6-Me2C6H3(2a), 2,6-Et2C6H3(2b), 2,6-iPr2C6H3(2c)]. X-ray crystallographic analysis reveals that the terminal Cr(II) atoms in 1aand 1band the Cr(II) atom in 1cpossess a distorted trigonal bipyramidal coordination environment with the Cipsoatom of the pincer ligand and two chloride atoms in the equator and the two imine nitrogen atoms in the apical positions, while the Cr(III) complexes 2a, 2b, and 2call adopt a distorted octahedral geometry around the chromium metal. Upon activation with trialkylaluminum and [Ph3C][B(C6F5)4]−, the Cr(III) complexes show high catalytic activity for isoprene polymerization and afford polyisoprene with predominately trans-1,4 units, whereas the Cr(II) complexes are inert under the same conditions. [ABSTRACT FROM AUTHOR]

A series of new half-sandwich chromium(III) complexes chelated with (2-((arylimino)methyl)phenyl)tetramethylcyclopentadienyl ligands, 2-(ArNCH)C6H4Me4CpCrCl2(Ar = 2,6-Me2C6H3(1), 2,6-Et2C6H3(2), 2,6-iPr2C6H3(3), 4-MeC6H4(4)), have been synthesized from the reaction of CrCl3with the lithium salt of the corresponding ligand 2-(ArNCH)C6H4Me4CpLi (Ar = 2,6-Me2C6H3(LiL1), 2,6-Et2C6H3(LiL2), 2,6-iPr2C6H3(LiL3), 4-MeC6H4(LiL4)). Free ligands HL1−HL4were prepared by the condensation reaction of 2-(tetramethylcyclopentadienyl)benzaldehyde with 2,6-dialkylaniline. The free ligands were characterized by 1H NMR spectroscopy, while the chromium(III) complexes were characterized by elemental analyses and single-crystal X-ray crystallography. The X-ray crystallographic analysis indicates that the imine N atom in these complexes coordinates to the central chromium atom. Upon activation with AlR3and Ph3CB(C6F5)4, these complexes exhibit high catalytic activity for ethylene polymerization and produce polyethylene with moderate to high molecular weights. These chromium(III) complexes can also be activated with AlR3alone. In the latter case, they show slightly lower catalytic activity for ethylene polymerization in comparison to the AlR3/Ph3CB(C6F5)4activated catalyst systems. The effects of ligand structure, polymerization temperature, AlR3, and Al/Cr molar ratio on the catalytic behavior of these complexes were examined. [ABSTRACT FROM AUTHOR]

Reactions of 2,6-(ArNCH)2C6H3Li with AlEt2Cl afford a number of NCN pincer aluminum complexes (2,6-(ArNCH)2C6H3)AlEt2(Ar = Ph (1), 2,6-Me2C6H3(2), 2,6-Et2C6H3(3), 2,6-iPr2C6H3(4)). Similar reactions of 2,6-(ArNCH)2C6H3Li with ZnEtCl produce bisligated zinc complexes (2,6-(ArNCH)2C6H3)2Zn (Ar = Ph (5), 2,6-Me2C6H3(6), 2,6-Et2C6H3(7)) and monoligated NCN pincer zinc complex (2,6-(ArNCH)2C6H3)ZnEt (Ar = 2,6-iPr2C6H3(8)). All complexes were characterized by 1H and 13C NMR spectroscopy, and the molecular structures of complexes 3, 4, 6, 7, and 8were determined by X-ray crystallography. The X-ray diffraction analysis reveals that both complexes 3and 4adopt a distorted trigonal-bipyramidal geometry around the aluminum central metal with three carbon atoms in the equator and the two imine nitrogen atoms in the apical positions. Complexes 6and 7adopt a distorted tetrahedral geometry around their zinc metal centers, while complex 8adopts a square-planar geometry around its metal center. All these Al and Zn complexes are efficient initiators for l-lactide ring-opening polymerization in the presence of benzyl alcohol, and the polymerization reaction takes place in an immortal manner. The productivity of the Zn complexes is generally higher than that of the Al complexes under similar conditions. [ABSTRACT FROM AUTHOR]

Tanshinones are abietane-type norditerpenoid quinone natural products that are the bioactive components of the Chinese medicinal herb Salvia miltiorrhizaBunge. The initial results from a functional genomics-based investigation of tanshinone biosynthesis, specifically the functional identification of the relevant diterpene synthases from S. miltiorrhiza, are reported. The cyclohexa-1,4-diene arrangement of the distal ring poises the resulting miltiradiene for the ensuing aromatization and hydroxylation to ferruginol suggested for tanshinone biosynthesis. [ABSTRACT FROM AUTHOR]

As a continuation of our studies on biomimetic chemistry and butterfly cluster chemistry, two series of “closed” and “open” butterfly [2Fe2Se] cluster complexes have been prepared in satisfactory yields. Thus, treatment of Fe3(CO)12with (HSeCH2)2CHOH in toluene at reflux gave the expected “closed” butterfly [2Fe2Se] cluster complex [(μ-SeCH2)2CH(OH)]Fe2(CO)6(A), whereas the “open” butterfly cluster complex (μ-EtSe)[(μ-SeCH2CH(OH)(CH2Br)]Fe2(CO)6(B) was unexpectedly produced along with complex Avia a sequential reaction of (μ-Se2)Fe2(CO)6with Et3BHLi, followed by treatment with (BrCH2)2CHOH. The other “closed” and “open” cluster complexes 1−6could be further prepared by the hydroxy transformation and CO substitution reactions of complexes Aand B. For example, (i) reaction of Awith PPh3and decarbonylating agent Me3NO afforded PPh3-monosubstituted complex [(μ-SeCH2)2CH(OH)]Fe2(CO)5(PPh3) (1), (ii) further reaction of 1with the acylating agent PhC(O)Cl in the presence of Et3N produced the benzoate-functionalized complex [(μ-SeCH2)2CH(O2CPh)]Fe2(CO)5(PPh3) (2), (iii) treatment of Awith the phosphatizing agent Ph2PCl in the presence of Et3N or simply with PhPCl2yielded the phosphite-functionalized complexes [(μ-SeCH2)2CH(OPPh2-η1)]Fe2(CO)5(3) and [(μ-SeCH2)2CH(OPPhCl-η1)]Fe2(CO)5(4), and (iv) treatment of Bwith 4-pyridinecarboxylic chloride or Ph2PCl in the presence of Et3N resulted in formation of the “open” butterfly cluster complexes (μ-EtSe)[μ-SeCH2CH(CH2Br)(O2CC5H4N-4)]Fe2(CO)6(5) and (μ-EtSe)[μ-SeCH2CH(CH2Br)(OPPh2-η1)]Fe2(CO)5(6). All the new complexes have been characterized by elemental analysis and spectroscopy, as well as for A, 1−4, and 6by X-ray crystallography. Both 1H and 77Se NMR spectral studies demonstrated that complexes Band 5consist of three isomers of e-Et/a-R, e-Et/e-R, and a-Et/e-R, whereas complex 6exists only as one isomer of e-Et/a-R. On the basis of an electrochemical study, it was found that the “closed” and “open” complexes Aand Bcan catalyze the proton reduction of TsOH and HOAc to give hydrogen, respectively. [ABSTRACT FROM AUTHOR]

A facile and efficient strategy for the syntheses of novel hyperbranched poly(ether amide)s (HPEA) from multihydroxyl primary amines and (meth)acryloyl chloride has been developed. The chemical structures of the HPEAs were confirmed by IR and NMR spectra. Analyses of SEC (size exclusion chromatography) and viscosity characterizations revealed the highly branched structures of the polymers obtained. The resultant hyperbranched polymers contain abundant hydroxyl groups. The thermoresponsive property was obtained from in situ surface modification of abundant OH end groups with N-isopropylacrylamide (NIPAAm). The study on temperature-dependent characteristics has revealed that NIPAAm-g-HPEA exhibits an adjustable lower critical solution temperature (LCST) of about 34−42 °C depending on the grafting degree. More interestingly, the work provided an interesting phenomenon where the HPEA backbones exhibited strong blue photoluminescence. [ABSTRACT FROM AUTHOR]

The tridentate ligand N-(2-((2,6-diisopropylphenylimino)methyl)phenyl)quinolin-8-amine ( HL) was prepared. Treatment of HLwith 1 equiv of Ln(CH 2SiMe 3) 3(THF) 2afforded the corresponding rare-earth metal bis(alkyl) complexes LLn(CH 2SiMe 3) 2(THF) n(Ln = Sc, n= 0 ( 1); Y, n= 1 ( 2); Lu, n= 0 ( 3)) in high yields. Variable-temperature 1H NMR spectral analysis showed that these complexes were fluxional at room temperature. Complexes 1and 3were THF-free, where the metal center adopted a square-pyramidal geometry, while in 2the metal center generated a distorted octahedral geometry owing to the coordination of a THF molecule. All these complexes catalyzed the ring-opening polymerization of ε-caprolactone with high activities in living fashion, among which the Lu complex was proved to be more active than its Sc and Y analogues. [ABSTRACT FROM AUTHOR]

The first aryldiimine NCN-pincer ligated rare earth metal dichiorides (2,6-(2,6-C6H3R2N=CH)2-C6H3)LnCl2(THF)2 (Ln = Y, R = Me (1), Et (2), iPr (3); R = Et, Ln = La (4), Nd (5), Gd (6), Sm (7), Eu (8), Tb (9), Dy (10), Ho (11), Yb (12), Lu (13)) were successfully synthesized via transmetalation between 2,6-(2,6-C6H3-R2N=CH)2-C6H3Li and LnCl3(THF)1~3.5. These complexes are isostructural monomers with two coordinating THF molecules, where the pincer ligand coordinates to the central metal ion in a κC:κN:κN′ tridentate mode, adopting a meridional geometry. Complexes 1-6, 9-11, and 13 combined with aluminum tris(alkyl)s and [Ph3C][B(C6F5)4] established a homogeneous Ziegler-Natta catalyst system, which exhibited high activities and excellent cis-1,4 selectivities for the polymerizations of butadiene (Tp = 25 °C, 99.9%; 0 °C, 100%) and isoprene (T~ = 25 °C, 98.8%). Remarkably, such high cis-1,4 selectivity almost remained at elevated polymerization temperatures up to 80 °C and did not vary with the type of the central lanthanide element, however, which was influenced obviously by the ortho substituent of the N-aryl ring of the ligands and the bulkiness of the aluminum alkyls. The Ln-Al bimetallic cations were considered as the active species. These results shed new light on improving the catalytic performance of the conventional Ziegler-Natta catalysts for the specific selective polymerization of dienes. [ABSTRACT FROM AUTHOR]

Lipase-catalyzed terpolymerizations were performed with the monomers trimethylolpropane (B3), 1,8-octanediol (B2), and adipic acid (A2). Polymerizations were performed in bulk, at 70 °C, for 42 h, using immobilized lipase B from Candida antartica(Novozyme-435) as a catalyst. To determine the substitution pattern of trimethylolpropane (TMP) in copolymers, model compounds with variable degrees of acetylation were synthesized. Inverse-gated 13C NMR spectra were recorded to first determine the chemical shift positions for mono-, di-, and trisubstituted TMP units and, subsequently, to determine substitution of TMP units along chains. Variation of TMP in the monomer feed gave copolymers with degrees of branching (DB) from 20% to 67%. In one example, a hyperbranched copolyester with 53 mol % TMP adipate units was formed in 80% yield, with Mw14 100 (relative to polystyrene standards), Mw/Mn5.3, and DB 36%. Thermal and crystalline properties of the copolyesters were studied by thermogravimetric analysis and differential scanning calorimetry. [ABSTRACT FROM AUTHOR]

Highly efficient catalytic microtubular engines are synthesized rapidly and inexpensively using an electrochemical growth of bilayer polyaniline/platinum microtubes within the conically shaped pores of a polycarbonate template membrane. These mass-produced microtubular engines are only 8 μm long, are self-propelled at an ultrafast speed (of over 350 body lengths s-1), and can operate in very low levels of the hydrogen peroxide fuel (down to 0.2%). The propulsion characteristics and optimization of these microtubular engines are described, along with their efficient operation in different biological environments which holds great promise for biomedical applications. [ABSTRACT FROM AUTHOR]

Fuel-free magnetically driven propulsion of flexible Au! Au/Ag/Ni nanowires, with a gold `head' and nickel `tail', linked by a partially dissolved and weakened silver bridge, is described. The flexible bridge facilitates the cyclic mechanical deformations under an external rotating magnetic field. Under such a field the nickel segment starts to rotate, facilitating the rotation of the gold segment at a different amplitude, hence breaking the system symmetry and inducing the movement. Forward (`pushing') and backward (`pulling') magnetically powered locomotion and a precise On/Off motion control are achieved by tailoring the length of the nickel and gold segments and modulating the magnetic field, respectively. Efficient locomotion in urine samples and in high-salt media is illustrated. The new magnetic nanowire swimmers can be prepared in large scale using a simple template electrodeposition protocol and offer considerable promise for diverse practical applications. [ABSTRACT FROM AUTHOR]

The article discusses a study which examined the growth of titania nanotubes through ceria colloids seeded deposition process in solution. The relation between the growth direction of the titania nanotubes and the crystalline direction of ceria colloids was examined. The interactions among colloidal particles played important roles for the solution vapor-liquid-solution-type growth of nanotubes.

The collective behavior of biological systems has inspired efforts toward the controlled assembly of synthetic nanomotors. Here we demonstrate the use of acoustic fields to induce reversible assembly of catalytic nanomotors, controlled swarm movement, and separation of different nanomotors. The swarming mechanism relies on the interaction between individual nanomotors and the acoustic field, which triggers rapid migration and assembly around the nearest pressure node. Such on-demand assembly of catalytic nanomotors is extremely fast and reversible. Controlled movement of the resulting swarm is illustrated by changing the frequency of the acoustic field. Efficient separation of different types of nanomotors, which assemble in distinct swarming regions, is illustrated. The ability of acoustic fields to regulate the collective behavior of catalytic nanomotors holds considerable promise for a wide range of practical applications. [ABSTRACT FROM AUTHOR]

The use of an ultrasound (US) field for rapid and reversible control of the movement of bubblepropelled chemically powered PEDOT/Ni/Pt microengines is demonstrated. Such operation reflects the USinduced disruption of normal bubble evolution and ejection, essential for efficient propulsion of catalytic microtubular engines. It offers precise speed control, with sharp increases and decreases of the speed at low and high US powers, respectively. A wide range of speeds can thus be generated by tuning the US power. Extremely fast changes in the motor speed (<0.1 s) and reproducible "On/Off" activations are observed, indicating distinct advantages compared to motion control methods based on other external stimuli. Such effective control of the propulsion of chemically powered microengines, including remarkable "braking" ability, holds considerable promise for diverse applications. [ABSTRACT FROM AUTHOR]

In this work, the high-temperature crystallographic evolution of crystalline phases in a complex lithium disilicate glass was investigated using synchrotron X-ray powder diffraction. The lattice parameters and unit cell volume of Li2SiO3 (LS), Li2Si2O5 (LS2), Li3PO4 (LP), and ZrO2 as a function of temperature were determined upon heating. It is found that the lattice parameter c of LS2 shows a "V"-shaped trend during heating. The crystallographic evolution of the LS2 phase has a close correlation with the LS phase, indicating the mutual interaction between LS and LS2 phases along the c axis during the nucleation/crystallization process. The phase evolution processes were different upon heating and cooling, and the unit cell volume of both LS and LP phases demonstrated different change rates. In this glass system, no LS2 was detected during cooling and the main phases formed during cooling process were LP, LS, β-cristobalite, and β-quartz. Interestingly, there were two forms of β-quartz with slightly different lattice constants, and the silica phases showed a near-zero expansion behavior. The crystallographic evolution mechanism is discussed. [ABSTRACT FROM AUTHOR]

A new nanomotor-based target isolation strategy, based on a "built-in" recognition capability, is presented. The concept relies on a poly(3-aminophenylboronic acid) (PAPBA)/Ni/Pt microtube engine coupling the selective monosaccharide recognition of the boronic acid-based outer polymeric layer with the catalytic function of the inner platinum layer. The PAPBA-based microrocket is prepared by membrane-templated electropolymerization of 3-aminophenylboronic acid monomer. The resulting boronic acid-based microengine itself provides the target recognition without the need for additional external functionalization. "On-the-fly" binding and transport of yeast cells (containing sugar residues on their wall) and glucose are illustrated. The use of the recognition polymeric layer does not hinder the efficient propulsion of the microengine in aqueous and physiological media. Release of the captured yeast cells is triggered via a competitive sugar binding involving addition of fructose. No such capture and transport are observed in control experiments involving other cells or microengines. Selective isolation of monosaccharides is illustrated using polystyrene particles loaded with different sugars. Such self-propelled nanomachines with a built-in recognition capability hold considerable promise for diverse applications. [ABSTRACT FROM AUTHOR]

A series of new titanium(IV) complexes with symmetric or asymmetric cis-9,10-dihydrophenanthrenediamide ligands, cis-9,10-PhenH2(NR)2Ti(OiPr)2 [PhenH2 = 9,10-dihydrophenanthrene, R = 2,6-iPr2C6H3 (2a), 2,6-Et2C6H3 (2b), 2,6-Me2C6H3 (2c)], cis-9,10-PhenH2(NR1)(NR2)Ti(OiPr)2 [R1 = 2,6-iPr2C6H3, R2 = 2,6-Et2C6H3 (2d); R1 = 2,6-iPr2C6H3, R2 = 2,6-Me2C6H3 (2e)], and [cis-9,10-PhenH2(NR1)2][o-C6H4(CH-NR2)]TiOiPr [R1 = 2,6-iPr2C6H3, R2 = 2,6-Et2C6H3 (3a); R1 = 2,6-iPr2C6H3, 2,6-Me2C6H3 (3b)], have been synthesized from the reactions of TiCl2(OiPr)2 with o-C6H4(CH-NR)Li [R = 2,6-iPr2C6H3, 2,6-Et2C6H3, 2,6-Me2C6H3]. The symmetric complexes 2a—2c were obtained from the reactions of TiCl2(OiPr)2 with 2 equiv of the corresponding o-C6H4(CH-NR)Li followed by intramolecular C—C bond-forming reductive elimination and oxidative coupling processes, while the asymmetric complexes 2d—2e were formed from the reaction of TiCl2(OiPr)2 with two different types of o-C6H4(CH-NR)Li sequentially. The complexes 3a and 3b were also isolated from the reactions for complexes 2d and 2e. All complexes were characterized by 1H and 13C NMR spectroscopy, and the molecular structures of 2a, 2b, 2e, and 3a were determined by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Removable tridentate directing groups inspired by pincer ligands have been designed to stabilize otherwise kinetically and thermodynamically disfavored 6- membered alkyl palladacycle intermediates. This family of directing groups enables regioselective remote hydrocarbofunctionalization of several synthetically useful alkene-containing substrate classes, including 4-pentenoic acids, allylic alcohols, homoallyl amines, and bis-homoallylamines, under Pd(II) catalysis. In conjunction with previous findings, we demonstrate regiodivergent hydrofunctionalization of 3-butenoic acid derivatives to afford either Markovnikov or anti-Markovnikov addition products depending on directing group choice. Preliminary mechanistic and computational data are presented to support the proposed catalytic cycle. [ABSTRACT FROM AUTHOR]

Here we report a highly conductive polypropylene-graphene nonwoven composite via direct coating of melt blown polypropylene (PP) nonwoven fabrics with graphene oxide (GO) dispersions in N,N-dimethylformamide (DMF), followed by the chemical reduction of GO with hydroiodic acid (HI). GO as an amphiphilic macromolecule can be dispersed in DMF homogeneously at a concentration of 5 mg/mL, which has much lower surface tension (37.5 mN/m) than that of GO in water (72.9 mN/m, at 5 mg/mL). The hydrophobic PP nonwoven has a surface energy of 30.1 mN/m, close to the surface tension of GO in DMF. Therefore, the PP nonwoven can be easily wetted by the GO/DMF dispersion without any pretreatment. Soaking PP nonwoven in a GO/DMF dispersion leads to uniform coatings of GO on PP-fiber surfaces. After chemical reduction of GO to graphene, the resulting PP/graphene nonwoven composite offers an electrical conductivity of 35.6 S m-1 at graphene loading of 5.2 wt %, the highest among the existing conductive PP systems reported, indicating that surface tension of coating baths has significant impact on the coating uniformity and affinity. The conductivity of our PP/graphene nonwoven is also stable against stirring washing test. In addition, here we demonstrate a monolithic supercapacitor derived from the PP-GO nonwoven composite by using a direct laser-patterning process. The resulted sandwich supercapacitor shows a high areal capacitance of 4.18 mF/cm2 in PVA-H2SO4 gel electrolyte. The resulting highly conductive or capacitive PP/graphene nonwoven carries great promise to be used as electronic textiles. [ABSTRACT FROM AUTHOR]

Effective endosomal escape remains as the "holy grail" for endocytosis-based intracellular drug delivery. To date, most of the endosomal escape strategies rely on small molecules, cationic polymers, or pore-forming proteins, which are often limited by the systemic toxicity and lack of specificity. We describe here a light-fueled liquid-metal transformer for effective endosomal escape-facilitated cargo delivery via a chemical-mechanical process. The nanoscale transformer can be prepared by a simple approach of sonicating a low-toxicity liquid-metal. When coated with graphene quantum dots (GQDs), the resulting nanospheres demonstrate the ability to absorb and convert photoenergy to drive the simultaneous phase separation and morphological transformation of the inner liquid-metal core. The morphological transformation from nanospheres to hollow nanorods with a remarkable change of aspect ratio can physically disrupt the endosomal membrane to promote endosomal escape of payloads. This metal-based nanotransformer equipped with GQDs provides a new strategy for facilitating effective endosomal escape to achieve spatiotemporally controlled drug delivery with enhanced efficacy. [ABSTRACT FROM AUTHOR]

Light-driven synthetic micro-/nanomotors have attracted considerable attention due to their potential applications and unique performances such as remote motion control and adjustable velocity. Utilizing harmless and renewable visible light to supply energy for micro-/nanomotors in water represents a great challenge. In view of the outstanding photocatalytic performance of bismuth oxyiodide (BiOI), visible-light-driven BiOI-based Janus micromotors have been developed, which can be activated by a broad spectrum of light, including blue and green light. Such BiOI-based Janus micromotors can be propelled by photocatalytic reactions in pure water under environmentally friendly visible light without the addition of any other chemical fuels. The remote control of photocatalytic propulsion by modulating the power of visible light is characterized by velocity and mean-square displacement analysis of optical video recordings. In addition, the self-electrophoresis mechanism has been confirmed for such visible-light-driven BiOI-based Janus micromotors by demonstrating the effects of various coated layers (e.g., Al2O3, Pt, and Au) on the velocity of motors. The successful demonstration of visible-light-driven Janus micromotors holds a great promise for future biomedical and environmental applications. [ABSTRACT FROM AUTHOR]

We describe and illustrate a three-step data-processing approach that enables individual congener groups of chlorinated paraffins (CPs) to be resolved in mass spectra obtained from either of two soft ionization methods: electron capture negative ionization mass spectrometry (ECNI-MS) or atmospheric pressure chemical ionization mass spectrometry (APCI-MS). In the first step, general fragmentation pathways of CPs are deduced from analysis of mass spectra of individual CP congeners. In the second step, all possible fragment ions in the general fragmentation pathways of CPs with 10 to 20 carbon atoms are enumerated and compared to mass spectra of CP mixture standards, and a deconvolution algorithm is applied to identify fragment ions that are actually observed. In the third step, isotope permutations of the observed fragment ions are calculated and used to identify isobaric overlaps, so that mass intensities of individual CP congener groups can be deconvolved from the unresolved isobaric ion signal intensities in mass spectra. For a specific instrument, the three steps only need to be done once to enable deconvolution of CPs in unknown samples. This approach enables congener group-level resolution of CP mixtures in environmental samples, and it opens up the possibility for quantification of congener groups. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) has been widely examined as a catalyst containing no precious metals for the hydrogen evolution reaction (HER); however, these examinations have utilized synthesized MoS2 because the pristine MoS2 mineral is known to be a poor catalyst. The fundamental challenge with pristine MoS2 is the inert HER activity of the predominant (0001) basal surface plane. In order to achieve high HER performance with pristine MoS2, it is essential to activate the basal plane. Here, we report a general thermal process in which the basal plane is texturized to increase the density of HER-active edge sites. This texturization is achieved through a simple thermal annealing procedure in a hydrogen environment, removing sulfur from the MoS2 surface to form edge sites. As a result, the process generates high HER catalytic performance in pristine MoS2 across various morphologies such as the bulk mineral, films composed of micron-scale flakes, and even films of a commercially available spray of nanoflake MoS2. The lowest overpotential (η) observed for these samples was η = 170 mV to obtain 10 mA/cm² of HER current density. [ABSTRACT FROM AUTHOR]

Intracellular H2O2 plays an important role in regulating a variety of cellular functions. Fluorescent probes that can make response to intracellular levels of H2O2 would provide valuable tools for revealing the functions of H2O2 in living organisms. However, traditional pH-in sensitive probes and lysosome-targetable probes can only provide spatially nonspecific visualization of intracellular H2O2 and specific sensing of lysosomal H2O2, respectively. In this work, we developed a H2O2-responsive and pH-switchable fluorescent probe (HP-Ll) which can make response sequentially to intracellular H2O2 and lysosomal pH. The fluorescent probe is comprised of a H2O2- responsive boronate moiety and a pH-switchable spirobenzopyran fluorophore. When the probe was applied for intracellular H2O2 sensing, only fluorescent emission from lysosomes is visible, and the fluorescence from other regions is not able to be obviously detected, which is due to the pH-switchable property of the spirobenzopyran fluorophore. Thus, the developed fluorescence probe enables the spatially confined (Le., lysosome-spedfic) visualization of the intracellular H2O2. We envisioned that this kind of fluorescent probe (or the proposed sensing strategy) would allow the visualization of the overall levels of intracellular H202 without interferences of possible fluorescent signals from other sources (e.g., dyes for cellular staining and multiplex analysis). [ABSTRACT FROM AUTHOR]

With 9-(2-tosylvinyl)-9H-purines as the dipolarophiles, a series of chiral azacyclic nucleosides with four continuous stereocenters were obtained in 86-99% yields, >20:1 dr, and 94 → 99% ee via the Cu(I)-catalyzed asymmetric [3 + 2] cycloaddition. Both (E)- and (Z)-9-(2-tosylvinyl)-9H-purines were suitable dipolarophiles, enriching the structure diversity of azacyclic nucleosides. Furthermore, when α-methyl imino ester was explored, the corresponding azacyclic nucleoside with a chiral quaternary stereocenter could also be afforded with excellent results. [ABSTRACT FROM AUTHOR]

With 9-(2-tosylvinyl)-9H-purines as the dipolarophiles, a series of chiral azacyclic nucleosides with four continuous stereocenters were obtained in 86-99% yields, >20:1 dr, and 94 ? 99% ee via the Cu(I)-catalyzed asymmetric [3 + 2] cycloaddition. Both (E)- and (Z)-9-(2-tosylvinyl)-9H-purines were suitable dipolarophiles, enriching the structure diversity of azacyclic nucleosides. Furthermore, when α-methyl imino ester was explored, the corresponding azacyclic nucleoside with a chiral quaternary stereocenter could also be afforded with excellent results. [ABSTRACT FROM AUTHOR]

The article presents a research about the development of a highly active half-metallocene chromium(III) catalyst system for ethylene polymerization. The new catalyst system, which is activated by trialkylaluminum, represents a remarkable addition to the limited list of half-metallocene type chromium ethylene polymerization catalysts.

We demonstrate an attractive nanomachine "capture and transport" target isolation strategy based on molecularly imprinted polymers (MIPs). MIP-based catalytic microtubular engines are prepared by electropolymerization of the outer polymeric layer in the presence of the target analyte (template). Tailor-made selective artificial recognition sites are thus introduced into the tubular microtransporters through complementary nanocavities in the outer polymeric layer. The new microtransporter concept is illustrated using bilayer poly(3,4-ethylenedioxythiophene) (PEDOT)/Pt-Ni microengines and fluorescein isothiocyanate (FITC)-labeled avidin (Av-FITC) as the template. The avidin-imprinted polymeric layer selectively concentrates the fluorescent-tagged protein target onto the moving microengine without the need for additional external functionalization, allowing "on-the-fly" extraction and isolation of Av-FITC from raw serum and saliva samples along with real-time visualization of the protein loading and transport. The new micromachine–MIP-based target isolation strategy can be extended to the capture and transport of other important target molecules, leading toward diverse biomedical and environmental applications. [ABSTRACT FROM AUTHOR]

New template-based self-propelled gold/nickel/polyaniline/platinum(Au/Ni/PANI/Pt) microtubular engines, functionalized with the ConcanavalinA (ConA) lectin bioreceptor, are shown to be extremely useful forthe rapid, real-time isolation of Escherichia coli(E. coli) bacteria from fuel-enhanced environmental,food, and clinical samples. These multifunctional microtube enginescombine the selective capture of E. coliwith theuptake of polymeric drug-carrier particles to provide an attractivemotion-based theranostics strategy. Triggered release of the capturedbacteria is demonstrated by movement through a low-pH glycine-baseddissociation solution. The smaller size of the new polymer-metal microenginesoffers convenient, direct, and label-free optical visualization ofthe captured bacteria and discrimination against nontarget cells. [ABSTRACT FROM AUTHOR]

Graphene is an intriguing two-dimensional material, which could be modified for achieving tunable properties with many applications. Photoluminescence of graphene due to plasmonic emission is well-known, however, attempts to develop strong luminescent graphene have been difficult. Synthesis of a graphene-based material with a dual optical functionality, namely quenching the fluorescence of organic dyes while maintaining its own self-luminescence, is an interesting and challenging proposition. Here, we demonstrate this optical bifunctionality in a lattice-modified luminescent graphene, where europium(III) cations are complexed with graphene through oxygen functionalities. After excitation at 314 nm, a hypersensitive red emission is observed at 614 and 618 nm showing the complexation of europium(III) with graphene. We demonstrate dual functionality of this graphene by the quenching of luminescence of Rhodamine-B while displaying its own hypersensitive red emission. The decay lifetime observed through the time-resolved spectroscopy confirms its potential for applications in biosensing as well as optoelectronics. [ABSTRACT FROM AUTHOR]

We describe here a new strategy for isolating target proteins from complex biological samples based on an aptamer-modified self-propelled microtube engine. For this purpose, a thiolated thrombin or a mixed thrombin-ATP aptamer (prehybridized with a thiolated short DNA) was coassembled with mercaptohexanol onto the gold surface of these microtube engines. The rapid movement of the aptamer-modified microtransporter resulted in highly selective and rapid capture of the target thrombin, with an effective discrimination against a large excess of nontarget proteins. Release of the captured thrombin can be triggered by the addition of ATP that can bind and displace the immobilized mixed thrombin-ATP aptamer in 20 min. The rapid loading and unloading abilities demonstrated by these selective microtransporters are illustrated in complex matrixes such as human serum and plasma. The new motion-driven protein isolation platform represents a new approach in bioanalytical chemistry based on active transport of proteins and offers considerable promise for diverse diagnostic applications. [ABSTRACT FROM AUTHOR]

A series of new rare-earth metal bis(alkyl) complexes [L1−3Ln(CH2SiMe3)2(THF)n] (L1= MeC4H2SCH2NC6H4(Ph)2PNC6H2Me3-2,4,6: Ln = Sc, n= 1 (1a); Ln = Lu, n= 1 (1b); L2= MeC4H2SCH2NC6H4(Ph)2PNC6H3Et2-2,6: Ln = Sc, n= 1 (2a); Ln = Lu, n= 1 (2b); Ln = Y, n= 1 (2c); L3= MeC4H2SCH2NC6H4(Ph)2PNC6H3iPr2-2,6: Ln = Sc, n= 0 (3a)) and L4Sc(CH2SiMe3)2(THF) (4a) (L4= C6H5CH2NC6H4(Ph)2PNC6H3Et2-2,6) have been prepared by reaction of rare-earth metal tris(alkyl)s with the corresponding HL1−4ligands via alkane elimination. Complexes 1a, 1b, 2a−2c, and 4aare monomeric with a coordinating THF molecule. Each metal ion is coordinated by a NPN ligand, two trans-located alkyl groups, and a THF molecule, forming a distorted trigonal-bipyramidal geometry. Complex 3ais THF-free, adopting a distorted tetrahedron geometry. In combination with AlR3and borate, these complexes have shown medium activity and good trans-1,4 selectivity for the polymerization of butadiene. The resultant polymer has moderate molecular weight (Mn= 10 000−18 000) with narrow molecular weight distribution (Mw/Mn< 1.6) and trans-1,4 regularity varying from 49.2% up to 91.3%. The catalyst performances are strongly dependent on the orthosubstituent of the N-aryl ring and the presence of the thiophene moiety of the ligands and the type of aluminum alkyls and the lanthanide metal used. The scandium complex 2adisplays the highest trans-1,4 selectivity. [ABSTRACT FROM AUTHOR]

ZnO nanorod/microrod arrays with controllable surface distribution densities were successfully synthesized on glass substrates via a low-temperature template-assisted aqueous solution growth method. The influences of the pH of the solution on the formation and continuing growth of ZnO crystals were studied. It was found that the variation of pH in the reaction system significantly affects the density of homogeneous nucleation on the template surface. With a low surface density of the nanorod arrays, the effects of solution composition on the growth of ZnO crystals can be clearly revealed, and these have been demonstrated with the formation of ZnO nanorods in Zn 2++ Al 3++ HMT solutions. [ABSTRACT FROM AUTHOR]

The N,N-bidentate ligands 2-(N-2,6-R)iminomethyl)pyrrole (HL1, R dimethylphenyl; HL2, R diisopropylphenyl) have been prepared. HL1reacted readily with 1 equiv of lanthanide tris(alkyl)s, Ln(CH2SiMe3)3(THF)2, affording lanthanide bis(alkyl) complexes L1Ln(CH2SiMe3)2(THF)n(1a, Ln Lu, n2; 1b, Ln Sc, n1) via alkane elimination. Reaction of the bulky ligand HL2with 1 equiv of Ln(CH2SiMe3)3(THF)2gave the bis(pyrrolylaldiminato) lanthanide mono(alkyl) complexes L22Ln(CH2SiMe3)(THF) (2a, Ln Lu; 2b, Ln Sc), selectively. The N,N-bidentate ligand HL3, 2-dimethylaminomethylpyrrole, reacted with Ln(CH2SiMe3)3(THF)2, generating bimetallic bis(alkyl) complexes of central symmetry (3a, Ln Y; 3b, Ln Lu; 3c, Ln Sc). Treatment of the N,N,N,N-tetradentate ligand H2L4, 2,2‘-bis(2,2-dimethylpropyldiimino)methylpyrrole, with equimolar Lu(CH2SiMe3)3(THF)2afforded a C2-symmetric binuclear complex (4). Complexes 3a, 3b, 3c, and 4represent rare examples of THF-free binuclear lanthanide bis(alkyl) complexes supported by non-cyclopentadienyl ligands. All complexes have been tested as initiators for the polymerization of isoprene in the presence of AlEt3and Ph3CB(C6F5)4. Complexes 1a, 1b, and 3ashow activity, and 1bis the most active initiator, whereas 2a, 2b, 3b, 3c, and 4are inert. The microstructure of the resultant polyisoprene has a cis-1,4 or trans-1,4 configuration depending on the initiator applied. [ABSTRACT FROM AUTHOR]

Structure-based strategy was employed to design flavonoid compounds to mimic the Bim BH3 peptide as a new class of inhibitors of the anti-apoptotic Bcl-2 proteins. The most potent compound, 4(BI-33), binds to Bcl-2 and Mcl-1 with Kivalues of 17 and 18 nM, respectively. Compound 4inhibits cell growth in the MDA-MB-231 breast cancer cell line with an IC50value of 110 nM and effectively induces apoptosis. [ABSTRACT FROM AUTHOR]