bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Structures of N‐Alkyl‐1,13‐dimethoxychromeno‐ [2,3,4‐kl]acridinium Salts: The Missing Azaoxa[4]helicenium
Authors: Sørensen Thomas Just , Madsen Anders Ø. , Laursen Bo W. 
Published: April 2014

AbstractHelical structures are interesting due to their inherent chirality. Helicenium ions are triarylmethylium structures twisted into configurationally stable helicenes through the introduction of two heteroatom bridges between the three aryl substituents. Of the configurationally stable [4]helicenium ions, derivatives with sulfur, oxygen and nitrogen bridges have already been synthesised. However, one [4]helicenium ion has proven elusive, until now. We present herein the first synthesis of the 1,13‐dimethoxychromeno[2,3,4‐kl]acridinium (DMCA+) [4]helicenium ion. A series of six differently N‐substituted DMCA+ ions as their hexafluorophosphate salts are reported. Their cation stability was evaluated and it was found that DMCA+ is ideally suited as a phase‐transfer catalyst with a pKR+ of 13.0. The selectivity of nucleophilic addition to the central carbon atom of DMCA+ has been demonstrated with diastereotopic ratios of up to 1:10. The single‐crystal structures of several of the DMCA+ salts were determined, and structural differences between N‐aryl‐ and N‐alkyl‐substituted cations were observed. The results of a comparative study of the photophysics of the [4]helicenium ions are presented. DMCA+ is found to be a potent red‐emitting dye with a fluorescence quantum yield of 20 % in apolar solvents and a fluorescence lifetime of 12 ns. [4]Helicenium ions, including DMCA+, all suffer from solvent‐induced quenching, which reduces the fluorescence quantum yields significantly (ϕfl<5 %) in polar solvents. A difference in photophysical properties is observed between N‐aryl‐ and N‐alkyl‐substituted DMCA+, which has tentatively been attributed to a difference in molecular conformation.
Synthesis, π‐Face‐Selective Aggregation, and π‐Face Chiral Recognition of Configurationally Stable C3‐Symmetric Propeller‐Chiral Molecules with a π‐Core
Authors: Saito Nozomi , Terakawa Ryo , Yamaguchi Masahiko 
Published: April 2014

AbstractThe C3‐symmetric propeller‐chiral compounds (P,P,P)‐1 and (M,M,M)‐1 with planar π‐cores perpendicular to the C3‐axis were synthesized in optically pure states. (P,P,P)‐1 possesses two distinguishable propeller‐chiral π‐faces with rims of different heights named the (P/L)‐face and (P/H)‐face. Each face is configurationally stable because of the rigid structure of the helicenes contained in the π‐core. (P,P,P)‐1 formed dimeric aggregates in organic solutions as indicated by the results of 1H NMR, CD, and UV/Vis spectroscopy and vapor pressure osmometry analyses. The (P/L)/(P/L) interactions were observed in the solid state by single‐crystal X‐ray analysis, and they were also predominant over the (P/H)/(P/H) and (P/L)/(P/H) interactions in solution, as indicated by the results of 1H and 2D NMR spectroscopy analyses. The dimerization constant was obtained for a racemic mixture, which showed that the heterochiral (P,P,P)‐1/(M,M,M)‐1 interactions were much weaker than the homochiral (P,P,P)‐1/(P,P,P)‐1 interactions. The results indicated that the propeller‐chiral (P/L)‐face interacts with the (P/L)‐face more strongly than with the (P/H)‐face, (M/L)‐face, and (M/H)‐face. The study showed the π‐face‐selective aggregation and π‐face chiral recognition of the configurationally stable propeller‐chiral molecules.
Incorporating Polyoxometalates into a Porous MOF Greatly Improves Its Selective Adsorption of Cationic Dyes
Authors: Yan Ai‐Xue , Yao Shuang , Li Yang‐Guang , Zhang Zhi‐Ming , Lu Ying , Chen Wei‐Lin , Wang En‐Bo 
Published: April 2014

AbstractVarious polyoxometalates (POMs) were successfully immobilized to the mesoporous coordination polymer MIL‐101 resulting in a series of POM–MOF composite materials POM@MIL‐101 (POM=K4PW11VO40, H3PW12O40, K4SiW12O40). These materials were synthesized by a simple one‐pot reaction of Keggin POMs, tetramethylammonium hydroxide (TMAH), terephthalic acid (H2bdc), and Cr3+ ions. XRD, FTIR, thermogravimetric analyses (TG), inductively coupled plasma (ICP) spectrometry, and energy‐dispersive X‐ray spectroscopy (EDX) collectively confirmed the successful combination of POMs and the porous framework. Further, these composites POM@MIL‐101 with different loading of POMs were achieved by variation of the POM dosage. Notably, the uptake capacity of MIL‐101 towards organic pollutants in aqueous solution was significantly improved by immobilization of hydrophilic POMs into cages of MIL‐101. An uptake capacity of 371 mg g−1, comparable to that of the graphene oxide sponges, and much higher than that of the commercial activated carbon, was achieved at room temperature in 5 min when dipping 20 mg PW11V@MIL‐101 in the methylene blue (MB) solution (100 mL of 100 mg L−1 MB solution). Further study revealed that the POM@MIL‐101 composite materials not only exhibited a fast adsorption rate towards dye molecules, but also possessed of selective adsorption ability of the cationic dyes in wastewater. For example, the adsorption efficiency of PW11V@MIL‐101 (10 mg) towards MB (100 mL of 10 mg L−1) could reach 98 % in the initial 5 min, and it could capture MB dye molecules from the binary mixture of the MB and MO with similar size. Also, the POM@MIL‐101 materials could be readily recycled and reused, and no POM leached in the dye adsorption process.
Thermal Methane Activation by La6O10− Cluster Anions
Authors: Meng Jing‐Heng , Deng Xiao‐Jiao , Li Zi‐Yu , He Sheng‐Gui , Zheng Wei‐Jun 
Published: April 2014

AbstractThe first example of a metal oxide cluster anion, La6O10− that can activate methane under ambient conditions is reported. This reaction is facilitated by the oxygen‐centered radical (O−⋅) and follows the hydrogen atom transfer mechanism. The La6O10− has a high vertical electron detachment energy (VDE=4.06 eV) and a high symmetry (C4v).
A Two‐Armed Lanthanoid‐Chelating Paramagnetic NMR Probe Linked to Proteins via Thioether Linkages
Authors: Liu Wei‐Min , Skinner Simon P. , Timmer Monika , Blok Anneloes , Hass Mathias A. S. , Filippov Dmitri V. , Overhand Mark , Ubbink Marcellus 
Published: April 2014

AbstractParamagnetic NMR probes provide valuable long‐range structural information on proteins and protein complexes. A new, stable, two‐armed lanthanoid probe is reported that can be attached to a protein site‐specifically via chemically inert thioether linkages.
Facile Synthesis and Theoretical Conformation Analysis of a Triazine‐Based Double‐Decker Rotor Molecule with Three Anthracene Blades
Authors: Kory Max J. , Bergeler Maike , Reiher Markus , Schlüter A. Dieter 
Published: April 2014

AbstractThe facile synthesis of a rotor‐shaped compound with two stacked triazine units, which are symmetrically connected by three anthracene blades through oxygen linkers, is presented. This new double‐decker, which is a potential monomer for two‐dimensional polymerization, was synthesized by using readily available, cheap building blocks, exploiting the known selectivity difference for the nucleophilic substitution of cyanuric chloride. The crystal structure of a C3h symmetric rotor‐shaped compound with 9,10‐dihydroanthracene blades, which is a direct precursor to the targeted monomer, and the crystal structure of the new double‐decker with the desired C3h symmetry, are also reported. The synthetic efforts were preceded by a computational analysis, which was triggered by the question of conformational stability of the potential monomer. Two stable conformers could be found, and the barrier for the transition path in the gas phase between these conformers was determined by quantum chemical calculations. Exploratory Born–Oppenheimer molecular‐dynamics simulations revealed a strong influence of solvent–solute interactions on the stability of the conformers, which resulted in an energetic preference of the C3h symmetric conformation of the double‐decker.
Designed Single‐Step Synthesis, Structure, and Derivative Textural Properties of Well‐Ordered Layered Penta‐coordinate Silicon Alcoholate Complexes
Authors: Li Xiansen , Michaelis Vladimir K. , Ong Ta‐Chung , Smith Stacey J. , Griffin Robert G. , Wang Evelyn N. 
Published: April 2014

AbstractThe controllable synthesis of well‐ordered layered materials with specific nanoarchitecture poses a grand challenge in materials chemistry. Here the solvothermal synthesis of two structurally analogous 5‐coordinate organosilicate complexes through a novel transesterification mechanism is reported. Since the polycrystalline nature of the intrinsic hypervalent Si complex thwarts the endeavor in determining its structure, a novel strategy concerning the elegant addition of a small fraction of B species as an effective crystal growth mediator and a sacrificial agent is proposed to directly prepare diffraction‐quality single crystals without disrupting the intrinsic elemental type. In the determined crystal structure, two monomeric primary building units (PBUs) self‐assemble into a dimeric asymmetric secondary BU via strong Na+O2− ionic bonds. The designed one‐pot synthesis is straightforward, robust, and efficient, leading to a well‐ordered (10ī)‐parallel layered Si complex with its principal interlayers intercalated with extensive van der Waals gaps in spite of the presence of substantial Na+ counter‐ions as a result of unique atomic arrangement in its structure. However, upon fast pyrolysis, followed by acid leaching, both complexes are converted into two SiO2 composites bearing BET surface areas of 163.3 and 254.7 m2 g−1 for the pyrolyzed intrinsic and B‐assisted Si complexes, respectively. The transesterification methodology merely involving alcoholysis but without any hydrolysis side reaction is designed to have generalized applicability for use in synthesizing new layered metal–organic compounds with tailored PBUs and corresponding metal oxide particles with hierarchical porosity.
Oxygenated Metabolites of n‐3 Polyunsaturated Fatty Acids as Potential Oxidative Stress Biomarkers: Total Synthesis of 8‐F3t‐IsoP, 10‐F4t‐NeuroP and [D4]‐10‐F4t‐NeuroP
Authors: Guy Alexandre , Oger Camille , Heppekausen Johannes , Signorini Cinzia , De Felice Claudio , Fürstner Alois , Durand Thierry , Galano Jean‐Marie 
Published: April 2014

AbstractA wide variety of metabolic products of polyunsaturated fatty acids is of paramount importance for improving our medical knowledge in the field of oxidized lipids. Two novel metabolites of n‐3 polyunsaturated fatty acids, 8‐F3t‐IsoP and 10‐F4t‐NeuroP as well as a deuterated derivative thereof were synthesized based on an acetylenic intermediate. An original approach achieved lateral chain insertion of 8‐F3t‐IsoP by a ring‐closing alkyne metathesis/semi‐reduction strategy together with a temporary tether.
Lithiated Primary Amine—A New Material for Hydrogen Storage
Authors: Chen Juner , Wu Hui , Wu Guotao , Xiong Zhitao , Wang Ruiming , Fan Hongjun , Zhou Wei , Liu Bin , Chua Yongshen , Ju Xiaohua , Chen Ping 
Published: April 2014

AbstractA facile method for synthesizing crystalline lithiated amines by ball milling primary amines with LiH was developed. The lithiated amines exhibit an unprecedented endothermic dehydrogenation feature in the temperature range of 150–250 °C, which shows potential as a new type of hydrogen storage material. Structural analysis and mechanistic studies on lithiated ethylenediamine (Li2EDA) indicates that Li may mediate the dehydrogenation through an α,β‐LiH elimination mechanism, creating a more energy favorable pathway for the selective H2 release.
Cyanoborohydride‐Based Ionic Liquids as Green Aerospace Bipropellant Fuels
Authors: Zhang Qinghua , Yin Ping , Zhang Jiaheng , Shreeve Jean'ne M. 
Published: April 2014

AbstractIn propellant systems, the most common bipropellants are composed of two chemicals, a fuel (or reducer) and an oxidizer. Currently, the choices for propellant fuels rely mainly on hydrazine and its methylated derivatives, even though they are extremely toxic, highly volatile, sensitive to adiabatic compression (risk of detonation), and, therefore, difficult to handle. With this background, the search for alternative green propellant fuels has been an urgent goal of space science. In this study, a new family of cyanoborohydride‐based ionic liquids (ILs) with properties and performances comparable to hydrazine derivatives were designed and synthesized. These new ILs as bipropellant fuels, have some unique advantages including negligible vapor pressure, ultra‐short ignition delay (ID) time, and reduced synthetic and storage costs, thereby showing great application potential as environmentally friendly fuels in bipropellant formulations.
Lanthanide Tris(β‐diketonates) as Useful Probes for Chirality Determination of Biological Amino Alcohols in Vibrational Circular Dichroism: Ligand to Ligand Chirality Transfer in Lanthanide Coordination Sphere
Authors: Miyake Hiroyuki , Terada Keiko , Tsukube Hiroshi 
Published: April 2014

ABSTRACTA series of lanthanide tris(β‐diketonates) functioned as useful chirality probes in the vibrational circular dichroism (VCD) characterization of biological amino alcohols. Various chiral amino alcohols induced intense VCD signals upon ternary complexation with racemic lanthanide tris(β‐diketonates). The VCD signals observed around 1500 cm−1 (β‐diketonate IR absorption region) correlated well with the stereochemistry and enantiomeric purity of the targeted amino alcohol, while the corresponding monoalcohol, monoamine, and diol substrates induced very weak VCD signals. The high‐coordination number and dynamic property of the lanthanide complex offer an effective chirality VCD probing of biological substrates. Chirality 26:293–299, 2014. © 2014 Wiley Periodicals, Inc.
Design, Synthesis, and Activity Evaluation of GK/PPARγ Dual‐Target‐Directed Ligands as Hypoglycemic Agents
Authors: Lu Jianxun , Lei Lei , Huan Yi , Li Yongqiang , Zhang Lijing , Shen Zhufang , Hu Wenxiang , Feng Zhiqiang 
Published: April 2014

AbstractBased on the multi‐target strategy to treat type 2 diabetes mellitus (T2DM), glucokinase/peroxisome proliferator‐activated receptor γ (GK/PPARγ) dual‐target molecules were constructed by the rational combination of pharmacophores from known GK activators and PPARγ agonists. A series of dual‐target agents were designed and synthesized, and their capacities to induce GK and PPARγ transcriptional activity were evaluated. Three of these compounds showed particularly high potency toward GK, moderate activity toward PPARγ, and their structure–activity relationships were preliminarily analyzed. The putative binding modes of one of the most promising compounds were also explored by molecular docking simulations with GK and PPARγ.
BRCA1 and BRCA2 germline mutations are frequently demonstrated in both high‐risk pancreatic cancer screening and pancreatic cancer cohorts
Authors: Lucas Aimee L. , Frado Laura E. , Hwang Caroline , Kumar Sheila , Khanna Lauren G. , Levinson Elana J. , Chabot John A. , Chung Wendy K. , Frucht Harold 
Published: April 2014

BACKGROUNDApproximately 10% of pancreatic ductal adenocarcinoma (PDAC) is due to a genetic predisposition, including the breast and ovarian cancer syndrome germline mutations BRCA1 and BRCA2. Knowledge of specific genetic mutations predisposing to PDAC may enable risk stratification, early detection, and the development of effective screening and surveillance programs. In the current study, the authors attempted to determine the diagnostic yield of testing for BRCA1/2 germline mutations in a PDAC screening cohort and a PDAC cohort referred for genetic testing.METHODSPatients in a high‐risk PDAC prevention and genetics program or those with a personal history of PDAC who were referred for genetic evaluation underwent testing for BRCA1/2 germline mutations. Clinical BRCA1/2 genetic testing included testing for the 3 Ashkenazi Jewish founder mutations or BRCA1/2 comprehensive testing.RESULTSA total of 37 patients without PDAC underwent BRCA1/2 testing at the study institution. Genetic testing identified 7 patients who were BRCA1/2 carriers for a yield of 18.9%. Six patients carried Ashkenazi Jewish founder mutations (3 with BRCA1 and 3 with BRCA2), and 1 patient was found to have a BRCA2 mutation on comprehensive testing. Thirty‐two patients with PDAC underwent BRCA1/2 genetic testing. Five patients had Ashkenazi Jewish founder mutations (2 with BRCA1 and 3 with BRCA2), and 2 patients were found to have BRCA2 mutations on comprehensive testing. The diagnostic yield was 7 of 32 patients (21.9%).CONCLUSIONSBRCA1/2 testing is useful in PDAC risk stratification and alters risk assignment and screening recommendations for mutation‐positive patients and their families. Clinical BRCA1/2 testing should be considered in patients of Ashkenazi Jewish descent with a personal history or family history of PDAC, even in the absence of a family history of breast and ovarian cancer. Cancer 2014;120:1960–1967. © 2014 American Cancer Society.
Independent oncogenic and therapeutic significance of phosphatase PRL‐3 in FLT3‐ITD–negative acute myeloid leukemia
Authors: Qu Shuang , Liu Bin , Guo Xiaoling , Shi Hongshun , Zhou Meifeng , Li Li , Yang Shulan , Tong Xiuzhen , Wang Haihe 
Published: April 2014

BACKGROUNDInternal tandem duplication of FMS‐like tyrosine kinase (FLT3‐ITD) is well known to be involved in acute myeloid leukemia (AML) progression, but FLT3‐ITD–negative AML cases account for 70% to 80% of AML, and the mechanisms underlying their pathology remain unclear. This study identifies protein tyrosine phophatase PRL‐3 as a key mediator of FLT3‐ITD–negative AML.METHODSA total of 112 FLT3‐ITD–negative AML patients were sampled between 2010 and 2013, and the occurrence of PRL‐3 hyperexpression in FLT3‐ITD–negative AML was evaluated by multivariate probit regression analysis. Overexpression or depletion of endogenous PRL‐3 expression with the specific small interfering RNAs was performed to investigate the role of PRL‐3 in AML progression. Xenograft models were also used to confirm the oncogenic role of PRL‐3.RESULTSCompared to healthy donors, PRL‐3 is upregulated more than 3‐fold in 40.2% of FLT3‐ITD–negative AML patients. PRL‐3 expression level is adversely correlated to the overall survival of the AML patients, and the AML relapses accompany with re‐upregulation of PRL‐3. Mechanistically, aberrant PRL‐3 expression promoted cell cycle progression and enhanced the antiapoptotic machinery of AML cells to drug cytotoxicity through downregulation of p21 and upregulation of Cyclin D1 and CDK2 and activation of STAT5 and AKT. Depletion of endogenous PRL‐3 sensitizes AML cells to therapeutic drugs, concomitant with apoptosis by upregulation of cleaved PARP (poly ADP ribose polymerase) and apoptosis‐related caspases. Xenograft assays further confirmed PRL‐3's oncogenic role in leukemogenesis.CONCLUSIONSOur results demonstrated that PRL‐3 is a novel independent crucial player in both FLT3‐ITD–positive and FLT3‐ITD–negative AML and could be a potential therapeutic target. Cancer 2014;120:2130–2141. © 2014 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.
Risk factors for gastrointestinal stromal tumor recurrence in patients treated with adjuvant imatinib
Authors: Joensuu Heikki , Eriksson Mikael , Hall Kirsten Sundby , Hartmann Jörg T. , Pink Daniel , Schütte Jochen , Ramadori Giuliano , Hohenberger Peter , Duyster Justus , Al‐Batran Salah‐Eddin , Schlemmer Marcus , Bauer Sebastian , Wardelmann Eva , Sarlomo‐Rikala Maarit , Nilsson Bengt , Sihto Harri , Ballman Karla V. , Leinonen Mika , DeMatteo Ronald P. , Reichardt Peter 
Published: April 2014

BACKGROUNDLittle is known about the factors that predict for gastrointestinal stromal tumor (GIST) recurrence in patients treated with adjuvant imatinib.METHODSRisk factors for GIST recurrence were identified, and 2 risk stratification scores were developed using the database of the Scandinavian Sarcoma Group (SSG) XVIII trial, where 358 patients with high‐risk GIST with no overt metastases were randomly assigned to adjuvant imatinib 400 mg/day either for 12 or 36 months after surgery. The findings were validated in the imatinib arm of the American College of Surgeons Oncology Group Z9001 trial, where 359 patients with GIST were randomized to receive imatinib and 354 were to receive placebo for 12 months.RESULTSFive factors (high tumor mitotic count, nongastric location, large size, rupture, and adjuvant imatinib for 12 months) were independently associated with unfavorable recurrence‐free survival (RFS) in a multivariable analysis in the SSGXVIII cohort. A risk score based on these 5 factors had a concordance index with GIST recurrence of 78.9%. When a simpler score consisting of the 2 strongest predictive factors (mitotic count and tumor site) was devised, the groups with the lowest, intermediate high, and the highest risk had 5‐year RFS of 76.7%, 47.5%, and 8.4%, respectively. Both scores were strongly associated with RFS in the validation cohort (P < .001 for each comparison).CONCLUSIONSThe scores generated were effective in stratifying the risk of GIST recurrence in patient populations treated with adjuvant imatinib. Patients with nongastric GIST with a high mitotic count are at a particularly high risk for recurrence. Cancer 2014;120:2325–2333 © 2014 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.
Colorectal cancer screening in high‐risk groups is increasing, although current smokers fall behind
Authors: Oluyemi Aminat O. , Welch Amy R. , Yoo Lisa J. , Lehman Erik B. , McGarrity Thomas J. , Chuang Cynthia H. 
Published: April 2014

BACKGROUNDThere is limited information about colorectal cancer (CRC) screening trends in high‐risk groups, including the black, obese, diabetic, and smoking populations. For this study, the authors evaluated national CRC screening trends in these high‐risk groups to provide insights into whether screening resources are being appropriately used.METHODSThis was a nationally representative, population‐based study using the Behavioral Risk Factor Surveillance System from the Centers for Disease Control. Data analysis was performed using bivariate analyses with weighted logistic regression.RESULTSIn the general population, CRC screening increased significantly from 59% to 65% during the years 2006 to 2010. The screening prevalence in non‐Hispanic blacks was 58% in 2006 and 65% in 2010. Among obese individuals, the prevalence of up‐to‐date CRC screening increased significantly from 59% in 2006 to 66% in 2010. Screening prevalence in individuals with diabetes was 63% in 2006 and 69% in 2010. The CRC screening prevalence in current smokers was 45% in 2006 and 50% in 2010. The odds of CRC screening in the non‐Hispanic black population, the obese population, and the diabetic population were higher than in non‐Hispanic whites, normal weight individuals, and the population without diabetes, respectively. Current smokers had significantly lower odds of CRC screening than never‐smokers in the years studied (2006: odds ratio [OR], 0.71; 95% confidence interval [CI], 0.66‐0.76; 2008: OR, 0.67; 95% CI, 0.63‐0.71; 2010: OR, 0.69; 95% CI, 0.66‐0.73).CONCLUSIONSThe prevalence of CRC screening in high‐risk groups is trending upward. Despite this, current smokers have significantly lower odds of CRC screening compared with the general population. Cancer 2014;120:2106–2113. © 2014 American Cancer Society.