bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tuning the Transition Temperature and Cooperativity of bapbpy‐Based Mononuclear Spin‐Crossover Compounds: Interplay between Molecular and Crystal Engineering
Authors: Arcis‐Castíllo Zulema , Zheng Sipeng , Siegler Maxime A. , Roubeau Olivier , Bedoui Salma , Bonnet Sylvestre 
Published: December 2011

AbstractIn this study, we show that 1) different isomers of the same mononuclear iron(II) complex give materials with different spin‐crossover (hereafter SCO) properties, and 2) minor modifications of the bapbpy (bapbpy=N6,N6′‐di(pyridin‐2‐yl)‐2,2′‐bipyridine‐6,6′‐diamine) ligand allows SCO to be obtained near room temperature. We also provide a qualitative model to understand the link between the structure of bapbpy‐based ligands and the SCO properties of their iron(II) compounds. Thus, seven new trans‐[Fe{R2(bapbpy)}(NCS)2] compounds were prepared, in which the R2bapbpy ligand bears picoline (9–12), quin‐2‐oline (13), isoquin‐3‐oline (14), or isoquin‐1‐oline (15) substituents. From this series, three compounds (12, 14, and 15) have SCO properties, one of which (15) occurs at 288 K. The crystal structures of compounds 11, 12, and 15 show that the intermolecular interactions in these materials are similar to those found in the parent compound [Fe(bapbpy)(NCS)2] (1), in which each iron complex interacts with its neighbors through weak NH⋅⋅⋅S hydrogen bonding and π–π stacking. For compounds 12 and 15, hindering groups located near the NH bridges weaken the NS intermolecular interactions, which is correlated to non‐cooperative SCO. For compound 14, the substitution is further away from the NH bridges, and the SCO remains cooperative as in 1 with a hysteresis cycle. Optical microscopy photographs show the strikingly different spatio‐temporal evolution of the phase transition in the noncooperative SCO compound 12 relative to that found in 1. Heat‐capacity measurements were made for compounds 1, 12, 14, and 15 and fitted to the Sorai domain model. The number n of like‐spin SCO centers per interacting domain, which is related to the cooperativity of the spin transition, was found high for compounds 1 and 14 and low for compounds 12 and 15. Finally, we found that although both pairs of compounds 11/12 and 14/15 are pairs of isomers their SCO properties are surprisingly different.
A Self‐Assembled Complex with a Titanium(IV) Catecholate Core as a Potential Bimodal Contrast Agent
Authors: Dehaen Geert , Eliseeva Svetlana V. , Kimpe Kristof , Laurent Sophie , Vander Elst Luce , Muller Robert N. , Dehaen Wim , Binnemans Koen , Parac‐Vogt Tatjana N. 
Published: December 2011

AbstractA ditopic chelating ligand (H64) that bears catechol and diethylenetriamine‐N,N,N′,N′′,N′′‐pentaacetate (DTPA) has been designed and shown to specifically bind lanthanide(III) ions at the DTPA core ([Ln(H24)(H2O)]−) and further self‐assemble with titanium(IV), thereby giving rise to the formation of a supramolecular metallostar complex with a lanthanide(III)‐to‐titanium(IV) ratio of 3:1, [(Ln4)3Ti(H2O)3]5− (Ln=La, Eu, Gd). The efficacy of the metallostar complex as a potential bimodal optical/magnetic resonance imaging (MRI) agent has been evaluated. Nuclear magnetic relaxation dispersion (NMRD) measurements for the [(Gd4)3Ti(H2O)3]5− complex have demonstrated an enhanced r1 relaxivity that corresponds to 36.9 s−1 mM−1 per metallostar molecule at 20 MHz and 310 K, which is a result of a decreased tumbling rate. The ability of the complex to bind to human serum albumin (HSA) was also examined by relaxometric measurements. In addition, upon UV irradiation the [(Gd4)3Ti(H2O)3]5− complex exhibits broad‐band green emission in the range 400–750 nm with a maximum at 490 nm. Taking into account the high relaxivity and luminescence properties, the [(Gd4)3Ti(H2O)3]5− complex is a good lead compound for the development of efficient bimodal contrast agents.
Construction of Metal–Organic Frameworks: Versatile Behaviour of a Ligand Containing Mono‐ and Bidentate Coordination Sites
Authors: Jacobs Tia , Hardie Michaele J. 
Published: December 2011

AbstractFive new coordination polymers based on a new 2,2′‐bipyridine derived ligand N,N′‐bis(pyridin‐4‐yl)‐2,2′‐bipyridine‐5,5′‐dicarboxamide (=L) are reported herein. Isostructural three‐dimensional coordination polymers with a rare (4,6)‐connected network of {44.62}3{46.89}2 topology were synthesised from Cu(NO3)2, Zn(NO3)2 or a mixture of Cu(NO3)2/Fe(BF4)2 with L in complexes {[Cu5L6]⋅(NO3)10⋅(H2O)18}∞ (1), {[Zn5L6]⋅(NO3)10⋅(H2O)18}∞ (2) and {[FexCuyL6]⋅(NO3)10⋅(H2O)18}∞ (3; where x+y=5). Complexes with two‐dimensional grid structures resulted from treatment with CoCl2 or Cd(NO3)2 with L in complexes {[CoLCl2]⋅DMF}∞ (4) and {CdL(NO3)2}∞ (5).
Striking Alkenol Versus Allenol Reactivity: Metal‐Catalyzed Chemodifferentiating Oxycyclization of Enallenols
Authors: Alcaide Benito , Almendros Pedro , Martínez del Campo Teresa , Redondo María C. , Fernández Israel 
Published: December 2011

AbstractAn efficient chemodivergent metal‐controlled methodology for the generation of different highly functionalized oxygen heterocycles from common enallenol substrates has been developed. Chemoselectivity control in the OC functionalization of an enallenol can be achieved through the choice of catalyst: AuCl3, PdCl2, and [PtCl2(CH2CH2)]2 exclusively afford dihydrofurans through selective activation of the allenol moiety, whereas FeCl3 solely gives tetrahydrofurans or tetrahydropyrans through selective activation of the alkenol moiety. We have also shown that a combination of metal‐mediated hydroalkoxylation and allenic aminocyclization reactions can lead to a useful preparation of the tetrahydrofuro[3,2‐b]piperidine core of the antimalarial alkaloid isofebrifugine. These divergent heterocyclization reactions have been developed experimentally and additionally, their mechanisms have been investigated by a theoretical study.
Addition of Alkynes to a Gallium Bis‐Amido Complex: Imitation of Transition‐Metal‐Based Catalytic Systems
Authors: Fedushkin Igor L. , Nikipelov Alexander S. , Morozov Alexander G. , Skatova Alexandra A. , Cherkasov Anton V. , Abakumov Gleb A. 
Published: December 2011

AbstractAcetylene, phenylacetylene, and alkylbutynoates add reversibly to (dpp‐bian)Ga–Ga(dpp‐bian) (dpp‐bian=1,2‐bis[(2,6‐diisopropylphenyl)‐imino]acenaphthene) to give addition products [dpp‐bian(R1CCR2)]Ga–Ga[(R2CCR1)dpp‐bian]. The alkyne adds across the GaNC section, which results in new carbon–carbon and carbon–gallium bonds. The adducts were characterized by electron absorption, IR, and 1H NMR spectroscopy and their molecular structures have been determined by single‐crystal X‐ray analysis. According to the X‐ray data, a change in the coordination number of gallium from three [in (dpp‐bian)Ga–Ga(dpp‐bian)] to four (in the adducts) results in elongation of the metal–metal bond by approximately 0.13 Å. The adducts undergo a facile alkynes elimination at elevated temperatures. The equilibrium between [dpp‐bian(PhCCH)]Ga–Ga[(HCCPh)dpp‐bian] and [(dpp‐bian)Ga–Ga(dpp‐bian) + 2 PhCCH] in toluene solution was studied by 1H NMR spectroscopy. The equilibrium constants at various temperatures (298≤T≤323 K) were determined, from which the thermodynamic parameters for the phenylacetylene elimination were calculated (ΔG°=2.4 kJ mol−1, ΔH°=46.0 kJ mol−1, ΔS°=146.0 J K−1mol−1). The reactivity of (dpp‐bian)Ga–Ga(dpp‐bian) towards alkynes permits use as a catalyst for carbon–nitrogen and carbon–carbon bond‐forming reactions. The bisgallium complex was found to be a highly effective catalyst for the hydroamination of phenylacetylene with anilines. For instance, with [(dpp‐bian)Ga–Ga(dpp‐bian)] (2 mol %) in benzene more than 99 % conversion of PhNH2 and PhCCH into PhNC(Ph)CH3 was achieved in 16 h at 90 °C. Under similar conditions, the reaction of 1‐aminoanthracene with PhCCH catalyzed by (dpp‐bian)Ga–Ga(dpp‐bian) formed a carbon–carbon bond to afford 1‐amino‐2‐(1‐phenylvinyl)anthracene in 99 % yield.
Amination with PdNHC Complexes: Rate and Computational Studies Involving Substituted Aniline Substrates
Authors: Hoi Ka Hou , Çalimsiz Selçuk , Froese Robert D. J. , Hopkinson Alan C. , Organ Michael G. 
Published: December 2011

AbstractThe amination of aryl chlorides with various aniline derivatives using the N‐heterocyclic carbene‐based Pd complexes Pd‐PEPPSI‐IPr and Pd‐PEPPSI‐IPent (PEPPSI=pyridine, enhanced precatalyst, preparation, stabilization, and initiation; IPr=diisopropylphenylimidazolium derivative; IPent= diisopentylphenylimidazolium derivative) has been studied. Rate studies have shown a reliance on the aryl chloride to be electron poor, although oxidative addition is not rate limiting. Anilines couple best when they are electron rich, which would seem to discount deprotonation of the intermediate metal ammonium complex as being rate limiting in favour of reductive elimination. In previous studies with secondary amines using PEPPSI complexes, deprotonation was proposed to be the slow step in the cycle. These experimental findings relating to mechanism were corroborated by computation. Pd‐PEPPSI‐IPr and the more hindered Pd‐PEPPSI‐IPent catalysts were used to couple deactivated aryl chlorides with electron poor anilines; while the IPr catalysis was sluggish, the IPent catalyst performed extremely well, again showing the high reactivity of this broadly useful catalyst.
Tandem Arrays of TEMPO and Nitronyl Nitroxide Radicals with Designed Arrangements on DNA
Authors: Atsumi Hiroshi , Maekawa Kensuke , Nakazawa Shigeaki , Shiomi Daisuke , Sato Kazunobu , Kitagawa Masahiro , Takui Takeji , Nakatani Kazuhiko 
Published: December 2011

AbstractHerein we describe one‐dimensional electron‐spin arrays consisting of two different organic radicals with the designed arrangement based on the DNA sequence. Two mismatch‐binding ligands carrying 2,2,6,6‐tetramethylpiperidine N‐oxide (TEMPO) and nitronyl nitroxide selectively bind to the predetermined sites on double stranded DNA. By using the two mismatch‐binding ligands carrying the organic radicals as the glue for DNA, electron‐spin assembly could be successfully synchronized with the hybridization. Periodically and tandemly arranged, two kinds of organic radical molecules at designed positions might be useful for an approach to build up scalable qubits of electron‐spin‐based quantum computing. The approach using DNA nanostructures as a scaffold to assembly functional small molecules can afford one of the promising ways for the future application of DNA nanostructures and nanotechnology.
A Perylene Diimide Rotaxane: Synthesis, Structure and Electrochemically Driven De‐Threading
Authors: Slater Benjamin J. , Davies E. Stephen , Argent Stephen P. , Nowell Harriott , Lewis William , Blake Alexander J. , Champness Neil R. 
Published: December 2011

AbstractThe first example of a [2]‐rotaxane in which a perylene diimide acts as a recognition site has been synthesised and characterised. The interlocked nature of the compound has been verified by both NMR studies and an X‐ray structure determination. Electrochemical investigations confirm that the nature of the redox processes associated with the perylene diimide are modified by the complexation process and that it is possible to mono‐reduce the [2]‐rotaxane to give a radical anion based rotaxane. Further reduction of the compound leads to de‐threading of the macrocycle from the reduced PTCDI recognition site. Our synthetic strategies confirm the potential of PTCDI‐based rotaxanes as viable targets for the preparation of complex interlocked species.
Stereoselective degradation of tebuconazole in rat liver microsomes
Authors: Shen Zhigang , Zhu Wentao , Liu Donghui , Xu Xinyuan , Zhang Ping , Zhou Zhiqiang 
Published: December 2011

AbstractThe aim of this study was to assess the stereoselectivity of two tebuconazole [(RS)‐1‐p‐chlorophenyl‐4,4‐dimethyl‐3‐(1H‐1,2,4‐triazol‐1‐ylmethyl)pentan‐3‐ol] enantiomers in in vitro system (rat liver microsomes). The analytes were extracted with acetic ether and concentrations were determined by high performance liquid chromatography (HPLC) with a cellulose tris(3,5‐dimethylphenylcarbamate)‐based chiral stationary phase. The degradation of rac‐tebuconazole (15 μM) followed first‐order kinetics, and the degradation of the S‐tebuconazole (t1/2 = 22.31 min) was faster than that of the R‐tebuconazole (t1/2 = 48.76 min), but no significant difference between the enantiomers was found in the respective incubation (7.5 μM for each). Kinetic assays showed that the Km was different between the two enantiomers (KmR = 14.83 ± 2.19, KmS = 12.23 ± 2.72). The interaction results revealed that there was competitive inhibition between S‐ and R‐form, and there was a significant difference between the IC50 of R‐ to S‐tebuconazole and S‐ to R‐tebuconazole (IC50R/S/IC50S/R = 4.98). Chirality. © 2011 Wiley Periodicals, Inc.
Study on the metabolic mechanism of chiral inversion of S‐Mandelic acid in vitro
Authors: Gao Ling‐Bo , Wang Jin‐Zhao , Yao Tong‐Wei , Zeng Su 
Published: December 2011

AbstractMandelic acid (MA) is generally used as a biological indicator of occupational exposure to styrene, which is classified as a class of hazardous environmental pollutants. It was found to undergo one‐directional chiral inversion (S‐MA to R‐MA) in Wistar and Sprague‐Dawley rats in vivo. This study was aimed to explore the metabolic mechanism of chiral inversion of S‐MA in vitro. S‐MA was converted to R‐MA in rat hepatocytes, whereas MA enantiomers remained unchanged in acidic and neutral phosphate buffers, HepG2 cells, and intestinal flora. In addition, the synthesized S‐MA‐CoA thioester was rapidly racemized and hydrolyzed to R‐MA by rat liver homogenate and S9, cytosolic and mitochondrial fractions. The data suggest that chiral inversion of S‐MA may involve the hydrolysis of S‐MA‐CoA, and its metabolic mechanism could be the same as that of 2‐arylpropionic acid (2‐APA) drugs. Chirality 24:86–95, 2012. © 2011 Wiley Periodicals, Inc.
On chirality transfer in electron donor–acceptor complexes. A prediction for the sulfinimine···BF3 system
Authors: Rode Joanna E. , Dobrowolski Jan CZ. 
Published: December 2011

AbstractStabilization energies of the electron donor–acceptor sulfinimine···BF3 complexes calculated at either the B3LYP/aug‐cc‐pVTZ or the MP2/aug‐cc‐pVTZ level do not allow to judge, whether the N‐ or O‐atom in sulfinimine is stronger electron‐donor to BF3. The problem seems to be solvable because chirality transfer phenomenon between chiral sulfinimine and achiral BF3 is expected to be vibrational circular dichroism (VCD) active. Moreover, the bands associated with the achiral BF3 molecule are predicted to be the most intense in the entire spectrum. However, the VCD band robustness analyses show that most of the chirality transfer modes of BF3 are unreliable. Conversely, variation of VCD intensity with change of intermolecular distance, angle, and selected dihedrals between the complex partners shows that to establish the robustness of chirality transfer mode. It is also necessary to determine the influence of the potential energy surface (PES) shape on the VCD intensity. At the moment, there is still no universal criterion for the chirality transfer mode robustness and the conclusions formulated based on one system cannot be directly transferred even to a quite similar one. However, it is certain that more attention should be focused on relation of PES shape and the VCD mode robustness problem. Chirality. © 2011 Wiley Periodicals, Inc.
Prognostic and therapeutic impact of the chromosome 20q13.2 ZNF217 locus amplification in ovarian clear cell carcinoma
Authors: Rahman Mohammed Tanjimur , Nakayama Kentaro , Rahman Munmun , Nakayama Naomi , Ishikawa Masako , Katagiri Atsuko , Iida Kouji , Nakayama Satoru , Otsuki Yoshiro , Shih Ie‐Ming , Miyazaki Kohji 
Published: December 2011

AbstractBACKGROUND:The goal of this study was to examine the clinical significance of ZNF217 amplification and assess whether ZNF217 could be a potential therapeutic target in ovarian clear cell carcinoma (OCCC).METHODS:ZNF217 expression and amplification in OCCC was assessed by immunohistochemistry, fluorescence in situ hybridization, and clinical data collected via a retrospective chart review. ZNF217 gene knockdown using silencing RNA (siRNA) was used to assess ZNF217 functions in OCCC cell lines.RESULTS:Gene amplification was identified in 12 of 60 (20.0%) OCCCs. ZNF217 copy number correlated significantly with ZNF217 protein expression (r = 0.341; P<.01). ZNF217 amplification correlated significantly with shorter progression‐free (P = .0042) and overall (P = .0199) survival. There were nonsignificant trends between high ZNF217 protein expression and poor progression‐free (P = .2594) and overall (P = .2199) survival. Multivariate analysis revealed ZNF217 gene amplification to be an independent prognostic factor for progression‐free and overall survival after standard platinum agent‐based chemotherapy (P = .0339 and P = .031, respectively). Profound growth inhibition and apoptosis were observed in ZNF217 siRNA‐treated cancer cells with gene amplification compared with cancer cells with ZNF217 moderate expression without ZNF217 gene amplification or with low ZNF217 expression.CONCLUSION:These findings indicate that ZNF217 overexpression is critical to growth and survival of OCCCs with ZNF217 gene amplification. Furthermore, they suggest that ZNF217 siRNA‐induced phenotypes depend on amplification status of OCCCs. Therefore, ZNF217‐targeted therapy may benefit OCCC patients with ZNF217 amplification. Cancer 2011. © 2011 American Cancer Society.
Inhibition of the NADPH oxidase regulates heme oxygenase 1 expression in chronic myeloid leukemia
Authors: Singh Melissa M. , Irwin Mary E. , Gao Yin , Ban Kechen , Shi Ping , Arlinghaus Ralph B. , Amin Hesham M. , Chandra Joya 
Published: December 2011

AbstractBACKGROUND:Patients with chronic myelogenous leukemia (CML) in blast crisis have a poor response to tyrosine kinase inhibitors designed to inhibit the breakpoint cluster region–v‐Abelson murine leukemia viral oncogene homolog 1 (BCR‐ABL1) oncogene. Recent work has demonstrated that heme oxygenase 1 (HO‐1) expression is increased in BCR‐ABL1–expressing cells and that the inhibition of HO‐1 in CML leads to reduced cellular growth, suggesting that HO‐1 may be a plausible target for therapy. The objective of the current study was to clarify the mechanism of HO‐1 overexpression and the role of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase as a contributor to this mechanism in CML.METHODS:HO‐1 expression was evaluated in bone marrow specimens from patients with CML in various stages of disease, in a transplantation‐based model for CML, and in CML cell lines. Chemical and genetic inhibition of the NADPH oxidase was carried out in CML cells.RESULTS:Specimens from patients with CML in blast crisis displayed higher levels of HO‐1 staining than specimens from patients with CML in chronic or accelerated phase. HO‐1 up‐regulation in BCR‐ABL1–expressing cells was suppressed by diphenyleneiodonium (DPI), a chemical inhibitor of the NADPH oxidase. Targeting the NADPH oxidase through RNA interference (RNAi) to Ras‐related C3 botulinum toxin substrate 1 (Rac1), a dominant‐negative Rac1 construct or an inhibitor of Rac1 activity also blunted HO‐1 protein expression. Moreover, inhibition of the NADPH oxidase by RNAi directed toward the 47‐kd cytosolic subunit of Nox (p47phox) similarly abrogated HO‐1 levels.CONCLUSIONS:BCR‐ABL1 expression up‐regulated HO‐1, a survival factor for CML cells. This up‐regulation was more pronounced in blast crisis CML relative to early stage disease and was mediated by the NADPH oxidase components Rac1 and p47phox. The expression of p47phox was increased in BCR‐ABL1–expressing cells. Cancer 2011. © 2011 American Cancer Society.
Temporal and geographic variations of Waldenstrom macroglobulinemia incidence
Authors: Wang Haijun , Chen Yiming , Li Fanglin , Delasalle Kay , Wang Jialei , Alexanian Raymond , Kwak Larry , Rustveld Luis , Du Xianglin L. , Wang Michael 
Published: December 2011

AbstractBACKGROUND:Waldenstrom macroglobulinemia (WM) is a non‐Hodgkin lymphoma (NHL) subtype. Little is known about the incidence and trends for this disease in the United States.METHODS:Twenty‐year data from the Surveillance, Epidemiology, and End Results (SEER) program were used for this study. SEER*Stat was used for data analysis.RESULTS:Of the 95,797 cases of NHL diagnosed between 1988 and 2007 in 9 SEER registries, 1835 (1.9%) were new cases of WM. Median age at diagnosis of WM was 73 years. The overall annual age‐adjusted incidence was 0.38 per 100,000 persons per year, which increased with age, ranging from 0.03 in patients aged <50 years to 2.85 in patients aged ≥80 years. The incidence of WM was higher in men (0.54) than in women (0.27; P < .001) and was higher in whites (0.41) than in African Americans (0.18) or other races (0.21; P < .05). The annual percentage change for the whole population was 1.01% (P > .05). The annual percentage change was 1.21% for whites (P < .05) and 0.80% (P > .05) for nonwhites. Significant annual percentage change increases were seen in the group aged 70 to 79 years (1.24%; P < .05) and in 3 geographic registries (P < .001).CONCLUSIONS:Although the overall incidence of WM remained steady over time, significant increases in incidence were seen over the past 20 years in whites, in those aged 70 to 79 years, and in 3 geographic registry areas. Cancer 2012. © 2011 American Cancer Society.
Confirmatory factor analysis of the Sexual Adjustment and Body Image Scale in women with gynecologic cancer
Authors: Ferguson Sarah E. , Urowitz Sara , Massey Christine , Wegener Marie , Quartey NaaKwarley , Wiljer David , Classen Catherine C. 
Published: December 2011

AbstractBACKGROUND:There is evidence that treatment of gynecologic cancer (GC) negatively affects body image and sexuality. The Sexual Adjustment and Body Image Scale (SABIS‐G) was developed to assess disturbances after diagnosis of GC. The objective of this study was to confirm the factor structure using a confirmatory factor analysis (CFA).METHODS:Women with a history of GC completed the SABIS‐G, a 9‐item self‐report measure. Ninety randomly selected participants were used for the exploratory factor analysis (EFA). CFA was performed on the remaining participants (n = 204) to confirm the factor structure developed in the EFA against a one‐factor model. Test‐retest reliability between baseline and follow‐up scores was assessed using the intraclass correlation coefficient.RESULTS:A total of 614 eligible patients were approached to participate: 398 (65%) consented to the study and 294 (74%) completed the SABIS‐G. The median age was 53 years (range, 27‐80 years) and the primary site of disease was: 120 (41%) uterine, 85 (29%) ovary, 82 (28%) cervix, and 7 (2%) other. A 2‐factor structure was favored in the EFA, and the CFA fit indices indicated an excellent fit for the 2‐factor measurement model (standardized root‐mean‐square residual = 0.05, non‐normed fit index = 0.97, comparative fit index = 0.98). Internal consistency reliability was high for the Body Image (0.88) and Sexual Adjustment (0.91) subscales, as was test‐retest reliability (0.89).CONCLUSIONS:These results confirm the 2‐factor structure of the SABIS‐G and provide evidence that this is a valid and reliable instrument to measure changes in body image and sexuality in women after a diagnosis of GC. Cancer 2012;118: 3095–104. © 2011 American Cancer Society.