bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of monoacylglycerol containing pinolenic acid via stepwise esterification using a cold active lipase
Authors: Pyo Young‐Gil , Hong Seung In , Kim Yangha , Kim Byung Hee , Kim In‐Hwan 
Published: July 2012

AbstractHigh purity monoacylglycerol (MAG) containing pinolenic acid was synthesized via stepwise esterification of glycerol and fatty acids from pine nut oil using a cold active lipase from Penicillium camembertii as a biocatalyst. Effects of temperature, molar ratio, water content, enzyme loading, and vacuum on the synthesis of MAG by lipase‐catalyzed esterification of glycerol and fatty acid from pine nut oil were investigated. Diacylglycerol (DAG) as well as MAG increased significantly when temperature was increased from 20 to 40°C. At a molar ratio of 1:1, MAG content decreased because of the significant increase in DAG content. Water has a profound influence on both MAG and DAG content through the entire course of reaction. The reaction rate increased significantly as enzyme loading increased up to 600 units. Vacuum was an effective method to reduce DAG content. The optimum temperature, molar ratio, water content, enzyme loading, vacuum, and reaction time were 20°C, 1:5 (fatty acid to glycerol), 2%, 600 units, 5 torr, and 24 h, respectively. MAG content further increased via lipase‐catalyzed second step esterification at subzero temperature. P. camembertii lipase exhibited esterification activity up to −30°C. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Impact of Helix Irregularities on Sequence Alignment and Homology Modeling of G Protein‐Coupled Receptors
Authors: Gonzalez Angel , Cordomí Arnau , Caltabiano Gianluigi , Pardo Leonardo 
Published: July 2012

AbstractComparison of the crystal structures of G protein‐coupled receptors (GPCRs) revealed backbone irregularities in the majority of the transmembrane (TM) helices. Among these, wide (π bulge) and tight (310) helical turns on TM2 and TM5 deserve special attention because of their proximity to the ligand binding site. These irregularities are related to residue insertion or deletion (reflected by inclusion of gaps in sequence alignments) accumulated during the evolution of these two helices. These findings have direct implications for the sequence alignments, phylogeny reconstruction, and homology modeling of class A GPCRs.
DYZ‐2‐90, a Novel Neo‐tanshinlactone Ring‐Opened Compound, Induces ERK‐Mediated Mitotic Arrest and Subsequent Apoptosis by Activating JNK in Human Colorectal Cancer Cells
Authors: Wang Li‐Ting , Pan Shiow‐Lin , Chen Tzu‐Hsuan , Dong Yizhou , Lee Kuo‐Hsiung , Teng Che‐Ming 
Published: July 2012

AbstractOver the past several decades, there has been a considerable and still growing interest in discovering natural products with anticancer potential from traditional Chinese medicine and increasing their anticancer selectivity by chemical modification. In addition, total synthesis of active compounds from natural products can overcome problems related to poor resource availability. DYZ‐2‐90 is a novel ring‐opened compound modified from neo‐tanshinlactone, which is isolated from Chinese medicinal herb tanshen. Both in vitro and in vivo tubulin polymerization assays showed that DYZ‐2‐90 directly bound to microtubules and rapidly induced tubulin depolymerization, inducing ERK‐mediated mitotic arrest and subsequent apoptosis by JNK activation in cancer cells, respectively. These results suggest that the fate of cells that undergo mitotic arrest is dictated by two competing networks activated by DYZ‐2‐90: the cytoprotective ERK pathway and the stress‐related JNK pathway. DYZ‐2‐90 is therefore a novel microtubule‐destabilizing agent and a new drug candidate for cancer therapy. This paper provides a new insight into the model of mitotic cell death, which was proposed in order to elucidate how cancer cells respond to microtubule‐interfering agents and prolonged cell cycle delay.
Evaluating Process Sustainability Using Flowsheet Monitoring
Authors: Barrett Jr W. M. , van Baten J. 
Published: July 2012

AbstractEnvironmental metric software can be used to evaluate the sustainability of a chemical based on data from the chemical process that is used to manufacture it. One problem in developing environmental metric software is that chemical process simulation packages typically do not make process flow data available via a mechanism that can be readily accessed by other software packages. While there have been past attempts to develop software that performs environmental sustainability calculations using process simulators, there is no standardized approach for obtaining the process information required to calculate metrics. This paper proposes a standardized mechanism for obtaining process information directly from a process simulation using a strongly integrated interface set, called flowsheet monitoring. The flowsheet monitoring interface provides read‐only access to the thermodynamics, unit operations and streams within the process model, and can be used to obtain the material flow data directly from the simulation. This material flow data can then be used to calculate process‐based environmental metrics.
Self‐Deprotonation and Colorization of 1,3‐Bis(dicyanomethylidene)indan in Polar Media: A Facile Route to a Minimal Polymethine Dye for NIR Fluorescence Imaging
Authors: Heo Jeongyun , Lim Chang‐Keun , Whang Dong Ryeol , Shin Jiyoung , Jeong Seo Young , Park Soo Young , Kwon Ick Chan , Kim Sehoon 
Published: July 2012

AbstractColorless 1,3‐bis(dicyanomethylidene)indan is an organic acid (pKa≈3.0) that turns blue in polar media owing to self‐deprotonation. Moreover, its colored conjugate base shows potential as a minimal anionic polymethine dye for probing biomolecules in cells and in vivo through noncovalent complexation and near‐infrared fluorescence signaling.
1H‐Azepine‐4‐amino‐4‐carboxylic Acid: A New α,α‐Disubstituted Ornithine Analogue Capable of Inducing Helix Conformations in Short Ala‐Aib Pentapeptides
Authors: Pellegrino Sara , Contini Alessandro , Clerici Francesca , Gori Alessandro , Nava Donatella , Gelmi Maria Luisa 
Published: July 2012

AbstractA very efficient synthesis of orthogonally protected 1H‐azepine‐4‐amino‐4‐carboxylic acid, abbreviated as Azn, a conformationally restricted analogue of ornithine, was realized. It was obtained on a gram scale in good overall yield in five steps, three of which did not require isolation of the intermediates, starting from the readily available 1‐amino‐4‐oxo‐cyclohexane‐4‐carboxylic acid. Both enantiomers were used for the preparation of pentapeptide models containing Ala, Aib, and Azn. Conformational studies using both spectroscopic techniques (NMR, CD) and molecular dynamics on model 5‐mer peptides showed that the (R)‐Azn isomer possesses a marked helicogenic effect.
Univalent Gallium and Indium Phosphane Complexes: From Pyramidal M(PPh3)3+ to Carbene‐Analogous Bent M(PtBu3)2+ (M=Ga, In) Complexes
Authors: Higelin Alexander , Sachs Ulf , Keller Sarah , Krossing Ingo 
Published: July 2012

AbstractIn a new oxidative route, Ag+[Al(ORF)4]− (RF=C(CF3)3) and metallic indium were sonicated in aromatic solvents, such as fluorobenzene (PhF), to give a precipitate of silver metal and highly soluble [In(PhF)n]+ salts (n=2, 3) with the weakly coordinating [Al(ORF)4]− anion in quantitative yield. The In+ salt and the known analogous Ga+[Al(ORF)4]− were used to synthesize a series of homoleptic PR3 phosphane complexes [M(PR3)n]+, that is, the weakly PPh3‐bridged [(Ph3P)3In–(PPh3)–In(PPh3)3]2+ that essentially contains two independent [In(PPh3)3]+ cations or, with increasing bulk of the phosphane, the carbene‐analogous [M(PtBu3)2]+ (M=Ga, In) cations. The MIP distances are 27 to 29 pm longer for indium, and thus considerably longer than the difference between their tabulated radii (18 pm). The structure, formation, and frontier orbitals of these complexes were investigated by calculations at the BP86/SV(P), B3LYP/def2‐TZVPP, MP2/def2‐TZVPP, and SCS‐MP2/def2‐TZVPP levels.
Hierarchical Superstructures with Control of Helicity from the Self‐Assembly of Chiral Bent‐Core Molecules
Authors: Lin Shih‐Chieh , Ho Rong‐Ming , Chang Chin‐Yen , Hsu Chain‐Shu 
Published: July 2012

AbstractHerein, two asymmetric chiral bent‐core molecules, 3‐[(4‐{[4‐(heptyloxy)benzoyl]oxy}benzoyl)oxy]‐phenyl‐4‐[(4‐{[(1R)‐1‐methylheptyl]oxy}benzoyl)oxy] benzoate (BC7R) and 3‐[(4‐{[4‐(heptyloxy)benzoyl]oxy}benzoyl)oxy]‐phenyl‐4‐[(4‐{[(1S)‐1‐methylheptyl]oxy}benzoyl)oxy] benzoate (BC7S), were synthesized to demonstrate control of the helicity of their self‐assembled hierarchical superstructures. Mirror‐imaged CD spectra showed a split‐type Cotton effect after the formation of self‐assembled aggregates of BC7R and BC7S, thereby suggesting the formation of intermolecular exciton couplets with opposite optical activities. Both twisted and helical ribbons with preferential helicity that corresponded to the twisting character of the intermolecular exciton couplet were found in the aggregates. The formation of helical ribbons was attributed to the merging of twisted ribbons through an increase in width to improve morphological stability. As a result, control of the helicity of hierarchical superstructures from the self‐assembly of bent‐core molecules could be achieved by taking advantage of the transfer of chiral information from the molecular level onto the hierarchical scale.
Multiporphyrin Arrays on Cyclophosphazene Scaffolds: Synthesis and Studies
Authors: Pareek Yogita , Ravikanth Mangalampalli 
Published: July 2012

AbstractThe stable and robust cyclotriphosphazene and cyclotetraphosphazene rings were used as scaffolds to prepare hexa‐ and octaporphyrin arrays by treating N3P3Cl6 and N4P4Cl8, respectively, with 5‐(4‐hydroxyphenyl)‐10,15,20‐tri(p‐tolyl)porphyrin (N4 core) or with its thiaporphyrin analogues (N3S and N2S2 cores) in THF in the presence of Cs2CO3 under simple reaction conditions. Thiaporphyrins were examined in addition to the normal porphyrin to tune the electronic properties of the resultant arrays. Observation of the molecular ion peaks in the mass spectra confirmed the molecular structures of the arrays. 1D and 2D NMR techniques were employed to characterize the multiporphyrin arrays in detail. The 1H NMR spectra of the multiporphyrin arrays each show a systematic set of signals, indicating that the porphyrin units are arranged in a symmetrical fashion around the cyclophosphazene rings. All signals in the 1H NMR spectra were assigned with the aid of COSY and NOESY experiments. The protons of each porphyrin unit are subject to upfield and downfield shifts because of the ring‐current effects of neighboring porphyrin units. Optical, electrochemical, and fluorescence studies of the arrays indicated that the porphyrin units retain their independent ground‐ and excited‐state characteristics. CuII and NiII derivatives of hexaporphyrin and octaporphyrin arrays containing N4 porphyrin units and N3S porphyrin units were synthesized, and complete metalation of the arrays was confirmed by their mass spectra and by detailed NMR characterization of the NiII derivatives of hexa‐ and octaporphyrin arrays containing N4 porphyrin units. Electrochemical studies indicated that CuII and NiII ions present in the thiaporphyrin units of the arrays can be stabilized in the +1 oxidation state, which is not possible with arrays containing normal porphyrin units.
Palladium‐Catalysed Cross‐Coupling of Vinyldisiloxanes with Benzylic and Allylic Halides and Sulfonates
Authors: Frye Elizabeth C. , O' Connor Cornelius J. , Twigg David G. , Elbert Bryony , Laraia Luca , Hulcoop David G. , Venkitaraman Ashok R. , Spring David R. 
Published: July 2012

AbstractThe Hiyama cross‐coupling reaction is a powerful method for carbon–carbon bond formation. To date, the substrate scope of this reaction has predominantly been limited to sp2–sp2 coupling reactions. Herein, the palladium‐catalysed Hiyama type cross‐coupling of vinyldisiloxanes with benzylic and allylic bromides, chlorides, tosylates and mesylates is reported. A wide variety of functional groups were tolerated, and the synthetic utility of the methodology was exemplified through the efficient total synthesis of the cytotoxic natural product bussealin A. In addition, the antiproliferative ability of bussealin A was evaluated in two cancer‐cell lines.
Electrospun V2O5 Nanostructures with Controllable Morphology as High‐Performance Cathode Materials for Lithium‐Ion Batteries
Authors: Wang Heng‐guo , Ma De‐long , Huang Yun , Zhang Xin‐bo 
Published: July 2012

AbstractPorous V2O5 nanotubes, hierarchical V2O5 nanofibers, and single‐crystalline V2O5 nanobelts were controllably synthesized by using a simple electrospinning technique and subsequent annealing. The mechanism for the formation of these controllable structures was investigated. When tested as the cathode materials in lithium‐ion batteries (LIBs), the as‐formed V2O5 nanostructures exhibited a highly reversible capacity, excellent cycling performance, and good rate capacity. In particular, the porous V2O5 nanotubes provided short distances for Li+‐ion diffusion and large electrode–electrolyte contact areas for high Li+‐ion flux across the interface; Moreover, these nanotubes delivered a high power density of 40.2 kW kg−1 whilst the energy density remained as high as 201 W h kg−1, which, as one of the highest values measured on V2O5‐based cathode materials, could bridge the performance gap between batteries and supercapacitors. Moreover, to the best of our knowledge, this is the first preparation of single‐crystalline V2O5 nanobelts by using electrospinning techniques. Interestingly, the beneficial crystal orientation provided improved cycling stability for lithium intercalation. These results demonstrate that further improvement or optimization of electrochemical performance in transition‐metal‐oxide‐based electrode materials could be realized by the design of 1D nanostructures with unique morphologies.
Control of Interpenetration and Gas‐Sorption Properties of Metal–Organic Frameworks by a Simple Change in Ligand Design
Authors: Prasad Thazhe Kootteri , Suh Myunghyun Paik 
Published: July 2012

AbstractIn metal–organic framework (MOF) chemistry, interpenetration greatly affects the gas‐sorption properties. However, there is a lack of a systematic study on how to control the interpenetration and whether the interpenetration enhances gas uptake capacities or not. Herein, we report an example of interpenetration that is simply controlled by the presence of a carbon–carbon double or single bond in identical organic building blocks, and provide a comparison of gas‐sorption properties for these similar frameworks, which differ only in their degree of interpenetration. Noninterpenetrated (SNU‐70) and doubly interpenetrated (SNU‐71) cubic nets were prepared by a solvothermal reaction of [Zn(NO3)2]⋅6 H2O in N,N‐diethylformamide (DEF) with 4‐(2‐carboxyvinyl)benzoic acid and 4‐(2‐carboxyethyl)benzoic acid, respectively. They have almost‐identical structures, but the noninterpenetrated framework has a much bigger pore size (ca. 9.0×9.0 Å) than the interpenetrated framework (ca. 2.5×2.5 Å). Activation of the MOFs by using supercritical CO2 gave SNU‐70′ and SNU‐71′. The simulation of the PXRD pattern of SNU‐71′ indicates the rearrangement of the interpenetrated networks on guest removal, which increases pore size. SNU‐70′ has a Brunauer–Emmett–Teller (BET) surface area of 5290 m2 g−1, which is the highest value reported to date for a MOF with a cubic‐net structure, whereas SNU‐71′ has a BET surface area of 1770 m2 g−1. In general, noninterpenetrated SNU‐70′ exhibits much higher gas‐adsorption capacities than interpenetrated SNU‐71′ at high pressures, regardless of the temperature. However, at P<1 atm, the gas‐adsorption capacities for N2 at 77 K and CO2 at 195 K are higher for noninterpenetrated SNU‐70′ than for interpenetrated SNU‐71′, but the capacities for H2 and CH4 are the opposite; SNU‐71′ has higher uptake capacities than SNU‐70′ due to the higher isosteric heat of gas adsorption that results from the smaller pores. In particular, SNU‐70′ has exceptionally high H2 and CO2 uptake capacities. By using a post‐synthetic method, the CC double bond in SNU‐70 was quantitatively brominated at room temperature, and the MOF still showed very high porosity (BET surface area of 2285 m2 g−1).
On the Prebiotic Synthesis of D‐Sugars Catalyzed by L‐Peptides: Assessments from First‐Principles Calculations
Authors: Cantillo David , Ávalos Martín , Babiano Reyes , Cintas Pedro , Jiménez José L. , Palacios Juan C. 
Published: July 2012

AbstractWhat accounts for a particular chiral selection in the case of a few sugars of prebiotic relevance, thereby mirroring the asymmetry observed in nature? By using first‐principles calculations, the generation of pentoses from glycolaldehyde (the initial product of the autocatalytic formose reaction), which has been detected in outer space), has been modeled by using L‐Val‐L‐Val as a primeval catalyst. Our theoretical study provides insight into the mechanism of this reaction and satisfactorily explains a few key molecular events. Our rationale agrees with the reported experimental data and shows that the D‐configuration is only favored for ribose. L‐pentoses are usually favored in the presence of L‐configured dipeptides, as observed experimentally, although no chiral selection could be observed in the case of xylose. These results confirm that a prebiotic sugar soup could be fine‐tuned in the presence of shorter peptides as catalysts and that D‐ribose would have also resulted in an advantageous imbalance for further amplification and chemical evolution.
Environment‐Sensitive Fluorophores with Benzothiadiazole and Benzoselenadiazole Structures as Candidate Components of a Fluorescent Polymeric Thermometer
Authors: Uchiyama Seiichi , Kimura Kohki , Gota Chie , Okabe Kohki , Kawamoto Kyoko , Inada Noriko , Yoshihara Toshitada , Tobita Seiji 
Published: July 2012

AbstractAn environment‐sensitive fluorophore can change its maximum emission wavelength (λem), fluorescence quantum yield (Φf), and fluorescence lifetime in response to the surrounding environment. We have developed two new intramolecular charge‐transfer‐type environment‐sensitive fluorophores, DBThD‐IA and DBSeD‐IA, in which the oxygen atom of a well‐established 2,1,3‐benzoxadiazole environment‐sensitive fluorophore, DBD‐IA, has been replaced by a sulfur and selenium atom, respectively. DBThD‐IA is highly fluorescent in n‐hexane (Φf=0.81, λem=537 nm) with excitation at 449 nm, but is almost nonfluorescent in water (Φf=0.037, λem=616 nm), similarly to DBD‐IA (Φf=0.91, λem=520 nm in n‐hexane; Φf=0.027, λem=616 nm in water). A similar variation in fluorescence properties was also observed for DBSeD‐IA (Φf=0.24, λem=591 nm in n‐hexane; Φf=0.0046, λem=672 nm in water). An intensive study of the solvent effects on the fluorescence properties of these fluorophores revealed that both the polarity of the environment and hydrogen bonding with solvent molecules accelerate the nonradiative relaxation of the excited fluorophores. Time‐resolved optoacoustic and phosphorescence measurements clarified that both intersystem crossing and internal conversion are involved in the nonradiative relaxation processes of DBThD‐IA and DBSeD‐IA. In addition, DBThD‐IA exhibits a 10‐fold higher photostability in aqueous solution than the original fluorophore DBD‐IA, which allowed us to create a new robust molecular nanogel thermometer for intracellular thermometry.
Easy Separation of Δ and Λ Isomers of Highly Luminescent [IrIII]‐Cyclometalated Complexes Based on Chiral Phenol‐Oxazoline Ancillary Ligands
Authors: Marchi Enrico , Sinisi Riccardo , Bergamini Giacomo , Tragni Michele , Monari Magda , Bandini Marco , Ceroni Paola 
Published: July 2012

AbstractA new class of neutral cyclometalated iridium(III) complexes with enantiomerically pure C1‐symmetric phenol‐oxazolines (3 a,b) have been synthetized in high yields and fully characterized. Resolution of the corresponding ΔR and ΛR or ΔS and ΛS isomers was easily achieved by conventional flash chromatography. The corresponding Δ and Λ helicities have been confirmed by CD spectroscopy and X‐ray crystallography. Regarding the absorption and luminescence properties with unpolarized light, no significant difference between Δ and Λ isomers has been observed. A strong blue luminescence is observed for deaerated solutions of complexes 5 a and 5 b in CH3CN.
Paramagnetic 19F Chemical Shift Probes that Respond Selectively to Calcium or Citrate Levels and Signal Ester Hydrolysis
Authors: Harvey Peter , Chalmers Kirsten H. , De Luca Elena , Mishra Anurag , Parker David 
Published: July 2012

AbstractParamagnetic magnetic resonance chemical shift probes containing a proximal CF3 group have been characterised. Different systems have been created that report reversible changes in calcium ion concentrations in the millimolar regime, signal the presence of citrate selectively in competitive aqueous media and allow the monitoring of remote ester/amide hydrolysis in relayed, irreversible transformations. Chemical shift non‐equivalence is amplified by the presence of the proximate lanthanide ion, with a mean separation between the CF3 group and the metal ion of 6.4 Å found for a thulium complex, in an X‐ray structure of the metal complex aqua adduct. The enhanced rate of longitudinal relaxation of the 19F nucleus allows faster data acquisition.
Pressure‐Induced Enhancement of Magnetic‐Ordering Temperature in an Organic Radical to 70 K: A Magnetostructural Correlation
Authors: Thomson Richard I. , Pask Christopher M. , Lloyd Gareth O. , Mito Masaki , Rawson Jeremy M. 
Published: July 2012

AbstractThe structure of the canted antiferromagnet β‐p‐NCC6F4CNSSN (1) was determined from synchrotron powder‐diffraction studies in the pressure range 0–21.6 kbar. Radical 1 crystallizes in the orthorhombic space group Fdd2, but undergoes an asymmetric contraction of the unit‐cell size with increasing pressure. At the molecular level, this contraction of the unit cell is simultaneously accommodated by: 1) an increase in twist angle between aryl and heterocyclic rings; and 2) a shortening of the intermolecular S⋅⋅⋅N contacts, which propagate the magnetic‐exchange pathway. DFT calculations based on the structures in this pressure range revealed an increase in the magnetic‐exchange interaction (J) with increasing pressure, and an excellent correlation was observed between J and the magnetic‐ordering temperature, which increased from 36 K at ambient pressure up to 70 K at 16 kbar.
Kinetic Control of the Supramolecular Chirality of Porphyrin J‐Aggregates
Authors: Sorrenti Alessandro , El‐Hachemi Zoubir , Arteaga Oriol , Canillas Adolf , Crusats Joaquim , Ribo Josep M. 
Published: July 2012

AbstractThe aggregation of achiral sulfonatophenyl‐ and phenyl‐meso‐substituted diprotonated porphyrins to chiral J‐aggregates is a hierarchical noncovalent polymerization process preceded by a critical nucleation stage. This allows significant enantiomeric excesses by the formation of a few primary nuclei and the control of their growth by the effect that flows (imperfect mixing) have on the secondary nucleation of the J‐aggregate particles. In addition, the results strongly suggest that when only one species of aggregate predominates, the CD signals of the three excitonic bands in the visible region (around 420, 490, and 700 nm) show the same sign. Thus, differences on their relative sign would be due to the presence of different species.