bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Optoelectronic Properties of Nanometer‐Sized and Highly Soluble Homocoupled Oligodiacetylenes
Authors: Pilzak Gregor S. , Baggerman Jacob , van Lagen Barend , Posthumus Maarten A. , Sudhölter Ernst J. R. , Zuilhof Han 
Published: January 2009

AbstractColor and shape of oligodiacetylenes: We synthesized a series of highly soluble homocoupled oligodiacetylenes (HODAs). The color of these oligomers is dependent on the molecular length and aggregation state (see picture). The optical properties of these materials were studied by using both steady‐state and time‐resolved spectroscopic techniques.magnified imageA new series of pure, nanometer‐sized and highly‐soluble homocoupled oligodiacetylenes (HODA) consisting of two symmetrical oligodiacetylene units was synthesized with high yield and on a multi‐milligram scale under mild, catalytic Sonogashira conditions. The λmax and the εmax of absorption for these HODAs show an increase with the chain elongation. The λmax converges to 450 nm for the longest members of the series at micromolar concentration and to 462 nm for thin drop‐casted films. An additional red‐shifted absorption is observed in the solid state and in solution at low temperatures, which is caused by aggregation. The λmax of the fluorescence emission increases with the chain length and reaches 492 nm for the longest oligomer. The fluorescence quantum yield has its maximum for the shortest oligomer and decreases rapidly for the longer ones. A similar trend is found for the fluorescence lifetime with a maximum of 100 ps for the homocoupled monomer. The rotational correlation time shows a linear increase with the oligomer length. This reveals a significant persistence length and indicates that the HODA molecules are fully stretched molecular rods (up to 8.2 nm).
Stereoselective Synthesis of the Functionalized C2–C10 Fragment of Clavulactone
Authors: ZHOU Zuozhong , SUO Dong , YANG Zhenyu , CHEN Lin , HU Taishan , YAO Zhujun 
Published: January 2009

AbstractA stereoselective synthesis of all functionalized C2–C10 fragment 13 of the antitumor marine natural product clavulactone was accomplished, starting from the commercially available 3‐methylglutaric acid anhydride. Desymmetrization of 3‐methylglutaric acid anhydride with (S)‐α‐phenylethanamine was successfully employed as a key step to embed the isolated C8‐methyl group with the correct absolute configuration (99% de). The C3–C4 cis‐double bond was stereospecifically furnished by an RCM (ring‐closing metathesis) approach. Fragment 13 contains all preset functionalities and will be a useful precursor for the convergent total synthesis of clavulactone.
Metal‐mediated gem‐Difluoroallylation of N‐Acylhydrazones: Highly Efficient Synthesis of α,α‐Difluorohomoallylic Amines
Authors: YUE Xuyi , QIU Xiaolong , QING Fengling 
Published: January 2009

AbstractIndium‐mediated gem‐difluoroallylation of aldehyde‐derived N‐acylhydrazones 1a–1q and 4a–4g with 3‐bromo‐3,3‐difluoropropene 2 afforded α,α‐difluorohomoallylic hydrazides 3a–3q and 5a–5g in high yields, respectively. Functional groups such as nitro, phenolic hydroxyl, benzyloxy and even C=C bonds of α,β‐unsaturated aldehydes were compatible under this mild and operationally simple gem‐difluoroallylic reaction condition. By means of substitution of Zn powder for indium, gem‐difluoroallylation of ketone‐derived N‐acylhydrazones 6a–6d also provided the corresponding α,α‐difluorohomoallylic hydrazides 7a–7d in medium yields. The N–N bond cleavage of the hydrazide 3a proceeded smoothly to give the corresponding primary gem‐difluorohomoallylic amine 8, which could be converted to gem‐difluoro‐δ‐substituted α,β‐unsaturated lactam 11 via acryloylation followed by ring closing metathesis (RCM) reaction.
Enantioselective Fluorescent Sensor Based on Calix[4]arene and S‐Binol for the Recognition of N‐Boc‐glutamate
Authors: HU Chenguang , HUANG Xiaohuan , CHEN Zhihong , HE Yongbing 
Published: January 2009

AbstractA new chiral macrocyclic receptor 4 based on calix[4]arene and S‐binol units was synthesized. The binding properties for anions were examined by fluorescence and 1H NMR spectra. The results of non‐linear curve fitting indicated that the receptor 4 formed a 1:1 stoichiometry complex with N‐Boc‐L‐ or D‐glutamate by multiple hydrogen bonding interactions, exhibiting a good enantioselective fluorescent recognition for the enantiomers of N‐Boc‐glutamate. The enantioselectivity: Kass(L)/Kass(D)=4.65. The different fluorescent response indicates that the receptor 4 could be used as a fluorescent chemosensor for N‐Boc‐glutamate.
Asymmetric Conjugate Addition of Unmodified Cyclic Ketones to Nitroolefins Using Aminophosphonate as the Organocatalyst
Authors: CHEN Gang , WANG Zheng , DING Kuiling 
Published: January 2009

Abstractα‐Aminophosphonates are an important class of compounds with diverse and useful biological activities. Despite that their structues are similar to that of proline, however, chiral cyclic α‐aminophosphonates have found little applications in catalytic asymmetric synthesis. In this paper, an enantiopure α‐aminophosphonate has been synthesized and was found to be effective as a chiral organocatalyst for the asymmetric conjugate addition of cycloketones to β‐nitrostyrenes. With a catalyst loading of 20 mol% and in the presence of 10 mol% of CF3COOH as a cocatalyst, the Michael adducts could be obtained with varying degrees of diastereo‐ and enantioselectivities (up to 97:3 and 90% ee respectively) under solvent‐free conditions.
Stereocontrolled Synthesis of (E)‐β,γ‐Unsaturated Esters via Palladium‐Catalyzed Cross‐Coupling of (E)‐Alkenylboronic Acids with α ‐Bromoacetic Esters
Authors: DUAN Yazhen , ZHANG Jianshe , YANG Jun , DENG Minzhi 
Published: January 2009

AbstractThe cross‐coupling reaction of trans‐alkenylboronic acids with ???α????‐bromoacetic esters was firstly studied. It was found that using Pd(OAc)2 as catalyst, a bulky electron‐rich phospine, (2‐dicyclohexylphospino‐biphenyl) as ligand, the reaction can be readily accomplished to give specific (E)‐???β???????? γ????‐unsaturated esters in high yields.
An Efficient Guanylation of Aromatic Amines Catalyzed by Samarium Diiodide
Authors: ZHU Xuehua , XU Fan , SHEN Qi 
Published: January 2009

AbstractAn efficient guanylation of aromatic amine with carbodiimide in the presence of a catalytic amount of samarium diiodide, a Lewis‐acid type precatalyst readily accessible, was developed. The reaction was carried out under mild conditions giving a variety of guanidines in good to excellent yields.
Automatic Identification of Antibodies in the Protein Data Bank
Authors: LI Xun , WANG Renxiao 
Published: January 2009

AbstractAn automatic method has been developed for identifying antibody entries in the protein data bank (PDB). Our method, called KIAb (Keyword‐based Identification of Antibodies), parses PDB‐format files to search for particular keywords relevant to antibodies, and makes judgment accordingly. Our method identified 780 entries as antibodies on the entire PDB. Among them, 767 entries were confirmed by manual inspection, indicating a high success rate of 98.3%. Our method recovered basically all of the entries compiled in the Summary of Antibody Crystal Structures (SACS) database. It also identified a number of entries missed by SACS. Our method thus provides a more complete mining of antibody entries in PDB with a very low false positive rate.
Synthesis, QSAR Study and Optimization of Propiophenone Oxime Derivatives
Authors: CHEN Liang , HUANG Ying , XIE Wei , CAO Jin , NI Changchun , SHEN Zhou , LI Xiuli , ZHANG Yibin , SHEN Tianxiang , YU Fei , LIU Bin , YUAN Liping , YAO Jianhua 
Published: January 2009

Abstract A method combining chemical and biological experiments and computer‐aided molecular design was used to optimize lead compounds with inhibiting activity against Sphaerotheca fuliginea. 44 propiophenone oxime derivatives were synthesized by 3‐amino‐1‐arylpropan‐1‐one oxime and halohydrocarbon. The results of biological test showed that most of these compounds had inhibiting activity against Sphaerotheca fuliginea. QSAR study was done based on the experimental data of the 44 compounds. CoMFA (rCV2, S and r2 are 0.577, 0.258 and 0.962, respectively) and CoMSIA (rCV2, S and r2 are 0.583, 0.343 and 0.932 respectively) models were contributed and employed to design three new lead compounds whose prediction carcinogenic and mutagenic toxicities show impossibility. The performances of the two models are satisfied because the test results showed that their prediction activity and observed activity are corresponding.
Xanthones from the Bark of Garcinia xanthochymus and Their 1,1‐Diphenyl‐2‐picrylhydrazyl Radical‐Scavenging Activity
Authors: ZHONG Fangfang , CHEN Yu , WANG Ping , FENG Huijin , YANG Guangzhong 
Published: January 2009

AbstractFive new xanthones, garcinenone A (1), B (3), C (4), D (7) and E (8), along with 7 known compounds were isolated from the EtOAc‐soluble extract of the bark of Garcinia xanthochymus, and their structures were elucidated by spectroscopic methods, especially 2D‐NMR techniques. Jacareubin (2), 1,4,6‐trihydroxy‐5‐methoxy‐7‐(3‐methyl‐2‐butenyl)xanthone (6), subeliptenone B (11) and symphoxanthone (12) were obtained from this plant for the first time. The isolated compounds exhibited potent antioxidant activity in the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging test with IC50 values in the 6.0–23.2 µmol/L. These results suggested that G. xanthochymus could be a promising rich source of natural antioxidant.
Photocatalytic Degradation of Dicofol and Pyrethrum with Boric and Cerous Co‐doped TiO2 under Light Irradiation
Authors: GONG Lifen , ZOU Jing , ZENG Jinbin , CHEN Wenfeng , CHEN Xi , WANG Xiaoru 
Published: January 2009

AbstractBoric and cerous co‐doped nano titanium dioxide (B/Ce co‐doped TiO2) was synthesized using a sol‐gel technique, which involved the hydrolyzation of tetrabutyl titanate with the addition of boric acid and cerous nitrate. The B/Ce co‐doped TiO2 was employed for the photocatalytic degradation of dicofol, cyfluthrin and fenvalerate under light irradiation. XRD, TEM, FT‐IR and UV‐Vis DRS methods were used to characterize the crystalline structure. Experimental results showed that only the anatase signal phase was found for B/Ce co‐doped TiO2, but multiplicate phases, including anatase, rutile and less brookite phases, were identified both in the pure TiO2 nanoparticles and Ce‐doped TiO2 nanoparticles. The band gap value of B/Ce co‐doped nano TiO2 was narrower than that of undoped nano TiO2. Compared to undoped TiO2, a stronger absorption in the range of 420 to 850 nm was found for B/Ce co‐doped nano TiO2, which presented a higher photocatalytic activity in the degradation of dicofol, cyfluthrin and fenvalerate than both Ce doped nano TiO2 and pure nano TiO2 under the same light irradiation.
Vanillezucker oder Vanillinzucker?
Authors: Sommer Katrin , Andreß Stefan , Kakoschke Annette , Wieczorek Robert , Hanisch Simone , Hanss Jan 
Published: January 2009

AbstractJedes Jahr werden weltweit ca. 2.000 Tonnen Vanillefrucht und ca. 12.000 Tonnen Vanillin produziert, um den Bedarf an dieser Aromanote zu decken ‐ sei es für Vanille‐Eis, Vanillin‐Zucker oder Cola. Der vorliegende Beitrag bietet sowohl fachliche Hintergrundinformationen als auch schulpraktische Möglichkeiten der experimentellen Erschließung des Themas „Vanille vs. Vanillin”︁ für die unterrichtliche Umsetzung. Es wird dabei die erfolgreiche Synthese von Vanillin aus Ligninsulfonsäure ebenso beschrieben wie Möglichkeiten der experimentellen Erschließung der Struktur von Vanillin. Anhand der Produkte „Vanillezucker”︁ und „Vanillinzucker”︁ erfolgt sowohl ein qualitativer Nachweis von Vanillin durch dünnschichtchromatographische Untersuchung als auch die quantitative Bestimmung von Vanillin im Vanillinzucker mittels Säure‐Base‐Titration.
The prognostic value of pretreatment CA 125 in patients with advanced ovarian carcinoma
Authors: Zorn Kristin K. , Tian Chunqiao , McGuire William P. , Hoskins William J. , Markman Maurie , Muggia Franco M. , Rose Peter G. , Ozols Robert F. , Spriggs David , Armstrong Deborah K. 
Published: January 2009

AbstractBACKGROUND:The objective of the current study was to determine the prognostic significance of a pretreatment serum CA 125 level in patients with advanced epithelial ovarian carcinoma (EOC) who received treatment with a standard chemotherapy regimen.METHODS:Patients with International Federation of Gynecology and Obstetrics stage III/IV ovarian carcinoma who were on 1 of 7 Gynecologic Oncology Group (GOG) phase 3 trials and received treatment with a standard regimen of intravenous cisplatin and paclitaxel were included. A Cox regression model was used to assess the impact of CA 125 levels drawn before the initiation of chemotherapy on progression‐free survival (PFS) both overall and by subgroup, including surgical debulking status, disease stage, and histologic subtype.RESULTS:In total, 1299 patients who were on the cisplatin/paclitaxel arms of the GOG trials were eligible. The median CA 125 level was 246 U/mL. Only 7.6% of patients had a normal CA 125 level (≤35 U/mL). The lowest median CA 125 level was observed in the group with mucinous tumors; however, 69% of women who had mucinous tumors had abnormal CA 125 levels. Shorter PFS was observed with increasing CA 125 and persisted in multivariate analysis. Overall and in the serous subgroup, a 1‐fold increase in CA 125 level was associated with a 7% increase in the hazard of disease progression (P < .001). This association was even more pronounced in patients who had stage III disease that was debulked to microscopic disease (15%; P = .003) and in patients who had endometrioid tumors (17%; P = .001).CONCLUSIONS:A normal CA 125 level in the setting of advanced EOC was rare even after surgical debulking. The pretreatment CA 125 level was an independent predictor of PFS in patients with advanced EOC who received a standard chemotherapy regimen, particularly in the setting of disease that was debulked to a microscopic residual and in the serous or endometrioid subtypes. Cancer 2009. © 2009 American Cancer Society.
Genetic polymorphisms of CYP2D6*10 and CYP2C19*2,*3 are not associated with prognosis, endometrial thickness, or bone mineral density in Japanese breast cancer patients treated with adjuvant tamoxifen
Authors: Okishiro Masatsugu , Taguchi Tetsuya , Jin Kim Seung , Shimazu Kenzo , Tamaki Yasuhiro , Noguchi Shinzaburo 
Published: January 2009

AbstractBACKGROUND:The authors investigated the impact of the genetic polymorphisms cytochrome P450 (CYP) family 2, subfamily D, polypeptide 6, allele *10 (CYP2D6*10) and CYP family 2, subfamily C, polypeptide 19, allele *2,*3 (CYP2C19*2,*3) on disease recurrence in patients with breast cancer who received adjuvant tamoxifen and evaluated the impact of those polymorphisms on endometrial thickness, bone mineral density (BMD), and serum total cholesterol levels.METHODS:Patients with primary breast cancer (n=173) who had hormone receptor‐positive tumors and who also received adjuvant tamoxifen were included in the current study. Genetic polymorphisms of CYP2D6*10 and CYP2C19*2,*3 were analyzed.RESULTS:Recurrence‐free survival (RFS) rates did not differ significantly between patients with the CYP2D6 *10/*10 genotype (n=40) and patients with the CYP2D6 wild‐type (wt)/wt or wt/*10 genotype (n=133) or between patients with the CYP2C19 *2/*2, *2/*3, or *3/*3 genotypes (n=41) and patients with the CYP2C19 wt/wt, wt/*2, or wt/*3 genotype (n=132). Multivariate analysis indicated that, even after adjustment for well established prognostic factors, these CYP2D6 or CYP2C19 genotypes were not associated significantly with the RFS rate. Moreover, these genotypes did not affect endometrial thickness, BMD, or total cholesterol levels 1 year after the start of tamoxifen treatment.CONCLUSIONS:Neither the CYP2D6 *10/*10 genotype nor the CYP2C19 genotype is likely to have a clinically significant impact on prognosis, endometrial thickness, BMD, or total cholesterol levels in Japanese patients with breast cancer who are treated with adjuvant tamoxifen. Cancer 2009. © 2009 American Cancer Society.
Carbon ion radiotherapy for pediatric patients and young adults treated for tumors of the skull base
Authors: Combs Stephanie E. , Nikoghosyan Anna , Jaekel Oliver , Karger Christian P. , Haberer Thomas , Münter Marc W. , Huber Peter E. , Debus Jürgen , Schulz‐Ertner Daniela 
Published: January 2009

AbstractBACKGROUND:The current study was conducted to evaluate the outcome of carbon ion radiotherapy (RT) in children and young adults with skull base chordomas and chondrosarcomas.METHODS:Between 1997 and 2007, 394 patients were treated with carbon ion RT at Gesellschaft für Schwerionenforschung in Darmstadt, Germany. Of these patients, 17 patients were aged ≤21 years. Seventeen of these young patients were treated for chordoma or low‐grade chondrosarcoma of the skull base and were analyzed in this study. Irradiation was performed after primary diagnosis in 14 patients (82%) and for recurrent tumors in 3 patients (18%). The authors applied a median total dose of 60 gray equivalents (Gy E) (range, 60‐66.6 Gy E) in a fractionation of 7 × 3 Gy E per week of carbon ion RT using the raster scan technique. All patients were observed prospectively on a regular basis after carbon ion RT.RESULTS:The median follow‐up time was 49 months. Treatment was well tolerated without severe side effects and could be completed on an outpatient basis in all patients without interruptions. One patient with chordoma developed tumor progression at 60 months after carbon ion RT. All other patients demonstrated no signs of tumor progression during follow‐up.CONCLUSIONS:Despite its promising outcome in children and young adults with chordomas and chondrosarcomas, further evaluation in a larger patient collective is required. Randomized studies comparing the outcome after carbon ion RT with proton RT are especially needed to evaluate the role of particle beams in the treatment of skull base tumors in children and young adults. Cancer 2009. © 2009 American Cancer Society.
Accuracy of clinical evaluation of locally advanced breast cancer in patients receiving neoadjuvant chemotherapy
Authors: Prati Raquel , Minami Christina A. , Gornbein Jeff A. , Debruhl Nanette , Chung Debbie , Chang Helena R. 
Published: January 2009

AbstractBACKGROUND:Physical examination (PE), mammography (MG), breast magnetic resonance imaging (MRI), fluorodeoxyglucose positron emission tomography (PET), and pathologic evaluation are used to assess primary breast cancer. To the authors' knowledge, their accuracy has not been well studied in patients receiving neoadjuvant chemotherapy. Accuracies of each modality in tumor and lymph node assessment in patients with T3/T4 tumors receiving neoadjuvant chemotherapy were compared.METHODS:Forty‐five patients of a prospective clinical trial studying T3‐T4M0 tumors were included. Patients received neoadjuvant chemotherapy: docetaxel/carboplatin with or without trastuzumab before and/or after surgery (depending on HER‐2/neu status and randomization). Tumor measurements by PE, MG, and MRI and lymph node status by PE and PET were obtained before and after neoadjuvant chemotherapy. Concordance among different clinical measurements was assessed and compared with the tumor and lymph node staging by pathology. Spearman correlation (r) and root mean square error (RMSE) were used to measure the accuracy of measurements among all modalities and between modalities and pathologic tumor size.RESULTS:Compared with the tumor size measured by PE, MRI was more accurate than MG at baseline (r = 0.559, RMSE = 35.4% vs r = 0.046, RMSE = 66.1%). After neoadjuvant chemotherapy, PE correlated better with pathology than MG or MRI (r = 0.655, RMSE = 88.6% vs r = 0.146, RMSE = 147.1% and r = 0.364, RMSE = 92.6%). Axillary lymph node assessment after neoadjuvant chemotherapy demonstrated high specificity but low sensitivity by PET and PE.CONCLUSIONS:Findings suggested that MRI was a more accurate imaging study at baseline for T3/T4 tumor, and PE correlated best with pathology finding. PET and PE both correctly predicted positive axillary lymph nodes but not negative lymph nodes. Cancer 2009. © 2009 American Cancer Society.
Decoupling 2D Inter‐ and Intrachain Energy Transfer in Conjugated Polymers
Authors: Shekhar Shashank , Aharon Eyal , Tian Nan , Galbrecht Frank , Scherf Ullrich , Holder Elisabeth , Frey Gitti L. 
Published: January 2009

AbstractIntercalation in layered SnS2 of blue‐emitting polyfluorene chains with known concentrations of fluorenone sterically hinders 3D polymer aggregation and π–π interchain interactions. Monitoring the fluorene‐to‐fluorenone energy transfer in quasi‐2D polymer monolayers (see schematic diagram) reveals that 2D energy transfer in conjugated polymers is mainly an interchain process.magnified imageThe dimensionality of conjugated polymer systems plays an important role in energy‐transfer processes, and 1D and 2D energy transfer of excitations are typically much slower than that between π‐stacked chains within a 3D polymeric solid. However, whether 2D energy transfer in conjugated polymers occurs mainly along polymer chains (intrachain), or between in‐plain‐adjacent polymer chains (interchain), has yet to be determined due to the difficulty of experimentally decoupling inter‐ and intrachain interaction in a 2D polymer system. This can be achieved by incorporating conjugated polymer chains into the planar galleries of layered matrices which sterically hinder polymer aggregation and π–π interchain interactions. Here, pristine blue‐emitting polyfluorene chains and polyfluorene chains with known concentrations of green‐emitting on‐chain fluorenone defects are either separately or collectively incorporated into layered SnS2. X‐ray powder diffraction of the composite films confirms incorporation of the polymer chains into the layered galleries. Monitoring the fluorene‐to‐fluorenone energy transfer as a function of fluorenone concentration and distribution in the layered galleries allows differentiation between inter‐ and intrachain fluorene–fluorenone energy transfer. It is found that, 2D energy transfer in conjugated polymers follows mainly an interchain process, despite the absence of π–π interchain interactions.
Group IV Coordination Chemistry of a Tetradentate Redox‐Active Ligand in Two Oxidation States
Authors: Blackmore Karen J. , Lal Neetu , Ziller Joseph W. , Heyduk Alan F. 
Published: January 2009

AbstractThe redox‐active ligand N,N′‐bis(3,5‐di‐tert‐butyl‐2‐phenoxy)‐1,2‐phenylenediamide [N2O2red]4– reacts with group IV metal salts to form six‐ and seven‐coordinate complexes [N2O2red]MLn (M = Ti, L = py, n = 2; M = Zr, Hf, L = thf, n = 3). The redox‐active ligand occupies four equatorial coordination sites in these complexes. In the case of the zirconium and hafnium complexes, two axial solvent molecules coordinate to the metal center with a third solvent molecule coordinating in the equatorial plane. In the case of the smaller titanium metal center, only two pyridine solvent molecules coordinate to the metal atom, leaving an open coordination site. All three complexes react with halogen oxidants to afford oxidative addition products [N2O2ox]MCl2Ln (M = Ti, n = 0; M = Zr, Hf, L = thf, n = 1), in which the redox‐active ligand is oxidized by two electrons to the cyclohexadienediimine state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)