1
|
Shimamura K, Shimojo F, Nakano A, Tanaka S. Ab initio molecular dynamics study of prebiotic production processes of organic compounds at meteorite impacts on ocean. J Comput Chem 2019; 40:349-359. [PMID: 30306615 DOI: 10.1002/jcc.25606] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 02/05/2023]
Abstract
Recent experiments concerning prebiotic materials syntheses suggest that the iron-bearing meteorite impacts on ocean during Late Heavy Bombardment provided abundant organic compounds associated with biomolecules such as amino acids and nucleobases. However, the molecular mechanism of a series of chemical reactions to produce such compounds is not well understood. In this study, we simulate the shock compression state of a meteorite impact for a model system composed of CO2 , H2 O, and metallic iron slab by ab initio molecular dynamics combined with multiscale shock technique, and clarify possible elementary reaction processes up to production of organic compounds. The reactions included not only pathways similar to the Fischer-Tropsch process known as an important hydrocarbon synthesis in many planetary processes but also those resulting in production of a carboxylic acid. It is also found that bicarbonate ions formed from CO2 and H2 O participated in some forms in most of these observed elementary reaction processes. These findings would deepen the understanding of the full range of chemical reactions that could occur in the meteorite impact events. © 2018 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Kohei Shimamura
- Graduate School of System Informatics, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan
| | - Fuyuki Shimojo
- Department of Physics, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 860-8555, Japan
| | - Aiichiro Nakano
- Collaboratory for Advanced Computing and Simulations, Department of Physics & Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, and Department of Biological Sciences, University of Southern California, Los Angeles, California, 90089-0242
| | - Shigenori Tanaka
- Graduate School of System Informatics, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501, Japan
| |
Collapse
|
2
|
Zhao T, Liu D, Li Z. Correlated evolution of sternal keel length and ilium length in birds. PeerJ 2017; 5:e3622. [PMID: 28761797 PMCID: PMC5533152 DOI: 10.7717/peerj.3622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 07/07/2017] [Indexed: 11/29/2022] Open
Abstract
The interplay between the pectoral module (the pectoral girdle and limbs) and the pelvic module (the pelvic girdle and limbs) plays a key role in shaping avian evolution, but prior empirical studies on trait covariation between the two modules are limited. Here we empirically test whether (size-corrected) sternal keel length and ilium length are correlated during avian evolution using phylogenetic comparative methods. Our analyses on extant birds and Mesozoic birds both recover a significantly positive correlation. The results provide new evidence regarding the integration between the pelvic and pectoral modules. The correlated evolution of sternal keel length and ilium length may serve as a mechanism to cope with the effect on performance caused by a tradeoff in muscle mass between the pectoral and pelvic modules, via changing moment arms of muscles that function in flight and in terrestrial locomotion.
Collapse
Affiliation(s)
- Tao Zhao
- School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
| | - Di Liu
- University of Chinese Academy of Sciences, Beijing, China.,Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.,Beijing Museum of Natural History, Beijing, China
| | - Zhiheng Li
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
3
|
Shimamura K, Shimojo F, Nakano A, Tanaka S. Meteorite Impact-Induced Rapid NH 3 Production on Early Earth: Ab Initio Molecular Dynamics Simulation. Sci Rep 2016; 6:38953. [PMID: 27966594 PMCID: PMC5155216 DOI: 10.1038/srep38953] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/15/2016] [Indexed: 01/05/2023] Open
Abstract
NH3 is an essential molecule as a nitrogen source for prebiotic amino acid syntheses such as the Strecker reaction. Previous shock experiments demonstrated that meteorite impacts on ancient oceans would have provided a considerable amount of NH3 from atmospheric N2 and oceanic H2O through reduction by meteoritic iron. However, specific production mechanisms remain unclear, and impact velocities employed in the experiments were substantially lower than typical impact velocities of meteorites on the early Earth. Here, to investigate the issues from the atomistic viewpoint, we performed multi-scale shock technique-based ab initio molecular dynamics simulations. The results revealed a rapid production of NH3 within several picoseconds after the shock, indicating that shocks with greater impact velocities would provide further increase in the yield of NH3. Meanwhile, the picosecond-order production makes one expect that the important nitrogen source precursors of amino acids were obtained immediately after the impact. It was also observed that the reduction of N2 proceeded according to an associative mechanism, rather than a dissociative mechanism as in the Haber-Bosch process.
Collapse
Affiliation(s)
- Kohei Shimamura
- Graduate School of System Informatics, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Fuyuki Shimojo
- Department of Physics, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | - Aiichiro Nakano
- Collaboratory for Advanced Computing and Simulations, Department of Physics &Astronomy, Department of Computer Science, Department of Chemical Engineering &Materials Science, and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0242, USA
| | - Shigenori Tanaka
- Graduate School of System Informatics, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| |
Collapse
|
4
|
Touboul M, Puchtel IS, Walker RJ. 182W evidence for long-term preservation of early mantle differentiation products. Science 2012; 335:1065-9. [PMID: 22345398 DOI: 10.1126/science.1216351] [Citation(s) in RCA: 180] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Late accretion, early mantle differentiation, and core-mantle interaction are processes that could have created subtle (182)W isotopic heterogeneities within Earth's mantle. Tungsten isotopic data for Kostomuksha komatiites dated at 2.8 billion years ago show a well-resolved (182)W excess relative to modern terrestrial samples, whereas data for Komati komatiites dated at 3.5 billion years ago show no such excess. Combined (182)W, (186,187)Os, and (142,143)Nd isotopic data indicate that the mantle source of the Kostomuksha komatiites included material from a primordial reservoir that represents either a deep mantle region that underwent metal-silicate equilibration or a product of large-scale magmatic differentiation of the mantle. The preservation, until at least 2.8 billion years ago, of this reservoir-which likely formed within the first 30 million years of solar system history-indicates that the mantle may have never been well mixed.
Collapse
Affiliation(s)
- Mathieu Touboul
- Department of Geology, University of Maryland, College Park, MD 20742, USA.
| | | | | |
Collapse
|
5
|
The tungsten isotopic composition of the Earth's mantle before the terminal bombardment. Nature 2011; 477:195-8. [PMID: 21901010 DOI: 10.1038/nature10399] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 07/28/2011] [Indexed: 11/09/2022]
Abstract
Many precious, 'iron-loving' metals, such as gold, are surprisingly abundant in the accessible parts of the Earth, given the efficiency with which core formation should have removed them to the planet's deep interior. One explanation of their over-abundance is a 'late veneer'--a flux of meteorites added to the Earth after core formation as a 'terminal' bombardment that culminated in the cratering of the Moon. Some 3.8 billion-year-old rocks from Isua, Greenland, are derived from sources that retain an isotopic memory of events pre-dating this cataclysmic meteorite shower. These Isua samples thus provide a window on the composition of the Earth before such a late veneer and allow a direct test of its importance in modifying the composition of the planet. Using high-precision (less than 6 parts per million, 2 standard deviations) tungsten isotope analyses of these rocks, here we show that they have a isotopic tungsten ratio (182)W/(184)W that is significantly higher (about 13 parts per million) than modern terrestrial samples. This finding is in good agreement with the expected influence of a late veneer. We also show that alternative interpretations, such as partial remixing of a deep-mantle reservoir formed in the Hadean eon (more than four billion years ago) or core-mantle interaction, do not explain the W isotope data well. The decrease in mantle (182)W/(184)W occurs during the Archean eon (about four to three billion years ago), potentially on the same timescale as a notable decrease in (142)Nd/(144)Nd (refs 3 and 6). We speculate that both observations can be explained if late meteorite bombardment triggered the onset of the current style of mantle convection.
Collapse
|
6
|
McGuinness ET. Some Molecular Moments of the Hadean and Archaean Aeons: A Retrospective Overview from the Interfacing Years of the Second to Third Millennia. Chem Rev 2010; 110:5191-215. [DOI: 10.1021/cr050061l] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Eugene T. McGuinness
- Department of Chemistry & Biochemistry, Seton Hall University, South Orange, New Jersey 07079-2690
| |
Collapse
|
7
|
Abstract
There is a growing body of evidence which suggests that the evolution of the planet drives the evolution of the biosphere. There have been 2 significant stages in Earth history when atmospheric oxygen levels rose rapidly, and both appear to be associated with supercontinent cycles. The earlier biospheric event, which extends across the Archean-Proterozoic boundary (ca. 3.0-2.2 Ga), has received little attention and is the focus of this study. Recent work on the Pilbara Craton of Western Australia has shown that concretion formed by microbial activity during the diagenesis of these sediments are absent from early Archean sediments but abundant in late Archean and early Paleoproterozoic successions of the Hamersley Basin, appearing abruptly in sedimentary rocks younger than 2.7 Ga. This study suggests that their internal architecture may have been defined by the diffusion of humic acids and the formation of polymer gels during diagenesis. The data imply that the biosphere expanded suddenly shortly after 3.0 Ga and may have begun to raise the oxygen levels of the oceanic water column earlier than thought-possibly as much as 300 my earlier.
Collapse
|
8
|
Priego-Capote F, Ye L, Shakil S, Shamsi SA, Nilsson S. Monoclonal behavior of molecularly imprinted polymer nanoparticles in capillary electrochromatography. Anal Chem 2008; 80:2881-7. [PMID: 18336010 DOI: 10.1021/ac070038v] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new approach based on miniemulsion polymerization is demonstrated for synthesis of molecularly imprinted nanoparticles (MIP-NP; 30-150 nm) with "monoclonal" binding behavior. The performance of the MIP nanoparticles is characterized with partial filling capillary electrochromatography, for the analysis of rac-propranolol, where (S)-propranolol is used as a template. In contrast to previous HPLC and CEC methods based on the use of MIPs, there is no apparent tailing for the enantiomer peaks, and baseline separation with 25,000-60,000 plate number is achieved. These effects are attributed to reduction of the MIP site heterogeneity by means of peripheral location of the core cross-linked NP and to MIP-binding sites with the same ordered radial orientation. This new MIP approach is based on the substitution of the functional monomers with a surfactant monomer, sodium N-undecenoyl glycinate (SUG) for improved inclusion in the MIP-NP structure and to the use of a miniemulsion in the MIP-NP synthesis. The feasibility of working primarily with aqueous electrolytes (10 mM phosphate with a 20% acetonitrile at pH 7) is attributable to the micellar character of the MIP-NPs, provided by the inclusion of the SUG monomers in the structure. To our knowledge this is the first example of "monoclonal" MIP-NPs incorporated in CEC separations of drug enantiomers.
Collapse
Affiliation(s)
- Feliciano Priego-Capote
- Department of Analytical Chemistry, Córdoba University, Annex C-3 Building, Campus of Rabanales, E-14071 Córdoba, Spain
| | | | | | | | | |
Collapse
|
9
|
Pasek M, Lauretta D. Extraterrestrial flux of potentially prebiotic C, N, and P to the early Earth. ORIGINS LIFE EVOL B 2008; 38:5-21. [PMID: 17846915 DOI: 10.1007/s11084-007-9110-5] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 07/30/2007] [Indexed: 10/22/2022]
Abstract
With growing evidence for a heavy bombardment period ending 4-3.8 billion years ago, meteorites and comets may have been an important source of prebiotic carbon, nitrogen, and phosphorus on the early Earth. Life may have originated shortly after the late-heavy bombardment, when concentrations of organic compounds and reactive phosphorus were enough to "kick life into gear". This work quantifies the sources of potentially prebiotic, extraterrestrial C, N, and P and correlates these fluxes with a comparison to total Ir fluxes, and estimates the effect of atmosphere on the survival of material. We find (1) that carbonaceous chondrites were not a good source of organic compounds, but interplanetary dust particles provided a constant, steady flux of organic compounds to the surface of the Earth, (2) extraterrestrial metallic material was much more abundant on the early Earth, and delivered reactive P in the form of phosphide minerals to the Earth's surface, and (3) large impacts provided substantial local enrichments of potentially prebiotic reagents. These results help elucidate the potential role of extraterrestrial matter in the origin of life.
Collapse
Affiliation(s)
- Matthew Pasek
- NAI LaPlace, University of Arizona, 1629 E. University Blvd, Tucson, AZ 85721, USA.
| | | |
Collapse
|
10
|
Elmer SL, Lemcoff NG, Zimmerman SC. Exploring the Reversibility of the Ring-Closing Metathesis Mediated Cross-linking of Dendrimers. Macromolecules 2007. [DOI: 10.1021/ma071233e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Stephanie L. Elmer
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801
| | - N. Gabriel Lemcoff
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801
| | - Steven C. Zimmerman
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801
| |
Collapse
|
11
|
Lu CH, Zhou WH, Han B, Yang HH, Chen X, Wang XR. Surface-imprinted core-shell nanoparticles for sorbent assays. Anal Chem 2007; 79:5457-61. [PMID: 17563116 DOI: 10.1021/ac070282m] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, we present a general protocol for the making of surface-imprinted core-shell nanoparticles via surface reversible addition-fragmentation chain-transfer (RAFT) polymerization using RAFT agent functionalized model silica nanoparticles as the chain-transfer agent. In this protocol, trichloro(4-chloromethylphenyl)silane was immobilized on the surface of SiO2 nanoparticles, forming chloromethylphenyl functionalized silica (silica-Cl). RAFT agent functionalized silica was subsequently produced by substitute reaction of silica-Cl with PhC(S)SMgBr. The grafting copolymerization of 4-vinylpyridine and ethylene glycol dimethacrylate using surface RAFT polymerization and in the presence of 2,4-dichlorophenoxyacetic acid as the template led to the formation of surface-imprinted core-shell nanoparticles. The resulting surface-imprinted core-shell nanoparticles bind the original template 2,4-D with an appreciable selectivity over structurally related compounds. The potential use of the surface-imprinted core-shell nanoparticles as the recognition element in the competitive fluorescent binding assay for 2,4-D was also demonstrated.
Collapse
Affiliation(s)
- Chun-Hua Lu
- The Key Lab of Analysis and Detection Technology for Food Safety of the MOE, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002, P.R. China
| | | | | | | | | | | |
Collapse
|
12
|
Gao D, Zhang Z, Wu M, Xie C, Guan G, Wang D. A surface functional monomer-directing strategy for highly dense imprinting of TNT at surface of silica nanoparticles. J Am Chem Soc 2007; 129:7859-66. [PMID: 17550249 DOI: 10.1021/ja070975k] [Citation(s) in RCA: 496] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper reports a surface functional monomer-directing strategy for the highly dense imprinting of 2,4,6-trinitrotoluene (TNT) molecules at the surface of silica nanoparticles. It has been demonstrated that the vinyl functional monomer layer of the silica surface can not only direct the selective occurrence of imprinting polymerization at the surface of silica through the copolymerization of vinyl end groups with functional monomers, but also drive TNT templates into the formed polymer shells through the charge-transfer complexing interactions between TNT and the functional monomer layer. The two basic processes lead to the formation of uniform core-shell TNT-imprinted nanoparticles with a controllable shell thickness and a high density of effective recognition sites. The high capacity and fast kinetics to uptake TNT molecules show that the density of effective imprinted sites in the nanoshells is nearly 5 times that of traditional imprinted particles. A critical value of shell thickness for the maximum rebinding capacity was determined by testing the evolution of rebinding capacity with shell thickness, which provides new insights into the effectiveness of molecular imprinting and the form of imprinted materials. These results reported here not only can find many applications in molecularly imprinting techniques but also can form the basis of a new strategy for preparing various polymer-coating layers on silica support.
Collapse
Affiliation(s)
- Daming Gao
- Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | | | | | | | | | | |
Collapse
|
13
|
Voicu R, Faid K, Farah AA, Bensebaa F, Barjovanu R, Py C, Tao Y. Nanotemplating for two-dimensional molecular imprinting. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:5452-8. [PMID: 17407335 DOI: 10.1021/la063562q] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
A new 2D molecular imprinting technique based on nanotemplating and soft-lithography techniques is reported. This technique allows the creation of target-specific synthetic recognition sites on different substrates using a uniquely oriented and immobilized template and the attachment of a molecularly imprinted polymer on a substrate. The molecularly imprinted polymer was characterized by AFM, fluorescence microscopy, and ATR-FTIR. We evaluated the rebinding ability of the sites with theophylline (the target molecule). The selectivity of the molecularly imprinted polymer was determined for the theophylline-caffeine couple. The molecularly imprinted polymer exhibited selectivity for theophylline, as revealed by competitive rebinding experiments. Fluorescence microscopy experiments provided complementary proof of the selectivity of the molecularly imprinted polymer surfaces toward theophylline. These selective molecularly imprinted polymers have the potential for chemical sensor applications. Because of its 2D nature, this novel chemical sensor technology can be integrated with many existing high-sensitivity multichannel detection technologies.
Collapse
Affiliation(s)
- Raluca Voicu
- Institute for Microstructural Sciences and Institute of Chemical Processing and Environmental Technology, National Research Council Canada, Ottawa, Ontario, K1A 0R6 Canada.
| | | | | | | | | | | | | |
Collapse
|
14
|
Dunetz JR, Sandstrom C, Young ER, Baker P, Van Name SA, Cathopolous T, Fairman R, de Paula JC, Akerfeldt KS. Self-assembling porphyrin-modified peptides. Org Lett 2006; 7:2559-61. [PMID: 15957890 DOI: 10.1021/ol050644h] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[structure: see text] We report the synthesis and characterization of a novel supramolecular assembly that features long-range electronic coupling between porphyrins covalently attached to a designed peptide scaffold. The resulting construct self-assembles to form extended organized aggregates in which the porphyrins engage in exciton coupling.
Collapse
Affiliation(s)
- Joshua R Dunetz
- Department of Chemistry, Haverford College, Haverford, Pennsylvania 19041-1392, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Lu G, Grossman JE, Lambert JB. General but Discriminating Fluorescent Chemosensor for Aliphatic Amines. J Org Chem 2006; 71:1769-76. [PMID: 16496960 DOI: 10.1021/jo0518405] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aliphatic amines are sensitively and discriminatively detected through binding with demethylated naphthol AS-BI (7-bromo-3-hydroxy-2-naphth-o-hydroxyanilide, 2) and fluorescence of the resulting complex. Recognition of the amine by the chemosensor 2 occurs via proton transfer of the naphtholic proton to the amine and is facilitated by the presence of the phenol group. Amine basicity is the primary controller of detection. Poorly basic aromatic and conjugated amines such as pyridine and aniline are not detected. Hydrogen bonding within the complex allows further differentiation of aliphatic amines. Doubly primary, conformationally flexible diamines are the most sensitive to detection, followed by secondary amines.
Collapse
Affiliation(s)
- Gang Lu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
| | | | | |
Collapse
|
16
|
The early record of life. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/164gm18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
17
|
Van Renterghem LM, Goethals EJ, Du Prez FE. Star-Shaped Poly(tetrahydrofuran) with Reactive End Groups: Design, MALDI-TOF Study, and Solution Behavior. Macromolecules 2005. [DOI: 10.1021/ma051846w] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lieven M. Van Renterghem
- Polymer Chemistry Research Group, Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium
| | - Eric J. Goethals
- Polymer Chemistry Research Group, Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium
| | - Filip E. Du Prez
- Polymer Chemistry Research Group, Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium
| |
Collapse
|
18
|
Liang CO, Fréchet JMJ. Incorporation of Functional Guest Molecules into an Internally Functionalizable Dendrimer through Olefin Metathesis. Macromolecules 2005. [DOI: 10.1021/ma050818a] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Catherine O. Liang
- Department of Chemistry, University of California, Berkeley, California 94720-1460, and Material Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720
| | - Jean M. J. Fréchet
- Department of Chemistry, University of California, Berkeley, California 94720-1460, and Material Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720
| |
Collapse
|
19
|
González-Toril E, Martínez-Frías J, Gómez Gómez JM, Rull F, Amils R. Iron meteorites can support the growth of acidophilic chemolithoautotrophic microorganisms. ASTROBIOLOGY 2005; 5:406-14. [PMID: 15941383 DOI: 10.1089/ast.2005.5.406] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Chemolithoautotrophy based on reduced inorganic minerals is considered a primitive energy transduction system. Evidence that a high number of meteorites crashed into the planet during the early period of Earth history led us to test the ability of iron-oxidizing bacteria to grow using iron meteorites as their source of energy. Here we report the growth of two acidophilic iron-oxidizing bacteria, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans, on a piece of the Toluca meteorite as the only source of energy. The alteration of the surface of the exposed piece of meteorite, the solubilization of its oxidized metal constituents, mainly ferric iron, and the formation of goethite precipitates all clearly indicate that iron-meteorite-based chemolithotrophic metabolism is viable.
Collapse
|
20
|
Suslick KS, Bhyrappa P, Chou JH, Kosal ME, Nakagaki S, Smithenry DW, Wilson SR. Microporous porphyrin solids. Acc Chem Res 2005; 38:283-91. [PMID: 15835875 DOI: 10.1021/ar040173j] [Citation(s) in RCA: 361] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Metalloporphyrins are exceedingly useful building blocks for the design and synthesis of molecularly based solids. The use of hydrogen bonding or metal ion coordination provides a wide range of framework solids. Using various polyfunctionalized porphyrins, we have created porous solids that are thermally robust and that retain their internal porosity upon loss of solvates. Their pore dimensions are comparable to zeolites, and they show shape and size selectivity in sorption of guest molecules and in epoxidation of alkenes.
Collapse
Affiliation(s)
- Kenneth S Suslick
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
| | | | | | | | | | | | | |
Collapse
|
21
|
Devanathan S, Salamon Z, Nagar A, Narang S, Schleich D, Darman P, Hruby V, Tollin G. Subpicomolar Sensing of δ-Opioid Receptor Ligands by Molecular-Imprinted Polymers Using Plasmon-Waveguide Resonance Spectroscopy. Anal Chem 2005; 77:2569-74. [PMID: 15828795 DOI: 10.1021/ac048476e] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Here we report, for the first time, the formation of a biomimetic covalently imprinted polymeric sensor for a target ligand, the delta-opioid G-protein coupled receptor agonist DPDPE, which reproducibly exhibits subpicomolar binding affinity in an aqueous environment. In addition to having a well-defined and homogeneous binding site, the imprinted polymer template is quite stable to storage in both the dry and wet states and has at least 6 orders of magnitude higher affinities than exhibited by similar peptide-based molecular-imprinted polymers (MIPs) thus far. A highly sensitive optical detection methodology, plasmon-waveguide resonance spectroscopy, was employed, capable of measuring binding in real time and discriminating between ligand molecules, without requiring labeling protocols (fluorophores or radioisotopes). The DPDPE-imprinted polymer showed a broad structure-activity relationship profile, not unlike that found for protein receptors. Such sensitivity and robustness of MIPs suggests potential applications ranging from biowarfare agent detection to pharmaceutical screening.
Collapse
Affiliation(s)
- Savitha Devanathan
- Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, Arizona 85721, USA
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Yang HH, Zhang SQ, Tan F, Zhuang ZX, Wang XR. Surface Molecularly Imprinted Nanowires for Biorecognition. J Am Chem Soc 2005; 127:1378-9. [PMID: 15686362 DOI: 10.1021/ja0467622] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Herein we present a novel method for preparation of surface molecularly imprinted size-monodisperse nanowires. The imprint molecule is immobilized on the pore walls of a silane-treated nanoporous alumina membrane. The nanopores are then filled with the monomer mixture, and the polymerization is initiated. The alumina membrane is subsequently removed by chemical dissolution, leaving behind polypyrrole nanowires with glutamic acid binding sites situated at the surface. These nanowires can be dissolved in aqueous media, and their applications therefore should be compatible with procedures in which biological antibodies might otherwise be used. For example, the analyte molecule can be tagged with various markers, such as fluorescence probes and enzymes, whereby the problem of steric hindrance is avoided. Furthermore, these surface-imprinted nanowires are likely suited for imprinting and recognition of large-molecular-weight peptides and proteins. Related work is currently being undertaken in our laboratory.
Collapse
Affiliation(s)
- Huang-Hao Yang
- The First Institute of Oceanography, SOA, Qingdao 266061, P.R. China.
| | | | | | | | | |
Collapse
|
23
|
Becker JJ, Gagné MR. Exploiting the synergy between coordination chemistry and molecular imprinting in the quest for new catalysts. Acc Chem Res 2004; 37:798-804. [PMID: 15491126 DOI: 10.1021/ar000102u] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of transition metal active sites by the molecular imprinting of polymerizable metal complexes into highly cross-linked organic polymers is described. The emphasis of this Account is on the synergy between the long-term goals associated with new catalyst development and the more short-term goal of addressing fundamental questions in coordination chemistry, particularly emphasizing stereochemistry and structure. An argument is presented that the latter is necessary for ultimately achieving the more difficult but more important goal of designer catalysts that achieve reaction selectivities and reactivities not obtainable with traditional homo- or heterogeneous catalysts.
Collapse
Affiliation(s)
- Jennifer J Becker
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | | |
Collapse
|
24
|
Beil JB, Lemcoff NG, Zimmerman SC. On the Nature of Dendrimer Cross-Linking by Ring-Closing Metathesis. J Am Chem Soc 2004; 126:13576-7. [PMID: 15493889 DOI: 10.1021/ja045885j] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ring-closing metathesis (RCM) mediated cross-linking of dendrimer 1 and it subunits was examined. Through the combined use of MALDI-MS-TOF, SEC, NMR, and X-ray crystallographic analysis it was shown that the cross-links are formed with the following order of preference: type d >/= type c > type b > type a.
Collapse
Affiliation(s)
- James B Beil
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
| | | | | |
Collapse
|
25
|
Elmer SL, Zimmerman SC. Cross-Linking Dendrimers with Allyl Ether End-Groups Using the Ring-Closing Metathesis Reaction. J Org Chem 2004; 69:7363-6. [PMID: 15471495 DOI: 10.1021/jo049368v] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A third generation Frechet-type dendrimer containing 24 allyl ether end-groups was synthesized, cross-linked using the ring-closing metathesis (RCM) reaction, and the core was removed hydrolytically without significant fragmentation. The results are analogous to those previously reported for homoallyl ether dendrimers (Wendland, M. S.; Zimmerman, S. C. J. Am. Chem. Soc. 1999, 121, 1389-1390) suggesting that the less readily available homoallyl ether dendrimers can be replaced by their allyl ethers analogues in a range of applications.
Collapse
Affiliation(s)
- Stephanie L Elmer
- Department of Chemistry, 600 S. Mathews Avenue, University of Illinois, Urbana, Illinois 61801, USA.
| | | |
Collapse
|
26
|
Lemcoff NG, Spurlin TA, Gewirth AA, Zimmerman SC, Beil JB, Elmer SL, Vandeveer HG. Organic Nanoparticles Whose Size and Rigidity Are Finely Tuned by Cross-Linking the End Groups of Dendrimers. J Am Chem Soc 2004; 126:11420-1. [PMID: 15366871 DOI: 10.1021/ja047055b] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dendrimers with molecular weights ranging from ca. 2700 to 11 000 and from 16 to 64 homoallyl ether end groups were cross-linked using the Grubbs ring-closing metathesis reaction. A combination of SEC, MALDI-TOF-MS, and AFM were used to characterize the cross-linked nanoparticles. The data suggest a significant decrease in volume with cross-linking and a concomitant increase in rigidity, both of which can be controlled independently with a fair degree of precision.
Collapse
Affiliation(s)
- N Gabriel Lemcoff
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Matthews Avenue, Urbana, IL 61801, USA
| | | | | | | | | | | | | |
Collapse
|
27
|
Bu J, Li R, Quah CW, Carpenter KJ. Propagation of PAMAM Dendrons on Silica Gel: A Study on the Reaction Kinetics. Macromolecules 2004. [DOI: 10.1021/ma040055b] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jie Bu
- Institute of Chemical and Engineering Sciences (ICES), No. 1 Pesek Road, Jurong Island, Singapore 627833
| | - Ruijiang Li
- Institute of Chemical and Engineering Sciences (ICES), No. 1 Pesek Road, Jurong Island, Singapore 627833
| | - Chee Wee Quah
- Institute of Chemical and Engineering Sciences (ICES), No. 1 Pesek Road, Jurong Island, Singapore 627833
| | - Keith J. Carpenter
- Institute of Chemical and Engineering Sciences (ICES), No. 1 Pesek Road, Jurong Island, Singapore 627833
| |
Collapse
|
28
|
Abstract
Sequential incorporation of a variety of functional groups forms the basis for specificity in biomacromolecules. Introduction of such diversity and sequencing ability in artificial macromolecules is fundamentally interesting. In this paper, three different synthetic approaches have been used to build dendrons and dendrimers in which all the monomer units are different from each other. The synthetic strategies described in this paper involve the use of (i) an ABB(p) monomer, (ii) an ABB' monomer, and (iii) an ABB(m) monomer. The complementarity and the versatility of these synthetic approaches should render them useful for a variety of applications.
Collapse
Affiliation(s)
- Kulandaivelu Sivanandan
- Department of Chemistry, University of Massachusetts, 701 LGRT-A, 710 North Pleasant Street, Amherst, Massachusetts 01003, USA
| | | | | |
Collapse
|
29
|
Guan Z, Roland JT, Bai JZ, Ma SX, McIntire TM, Nguyen M. Modular domain structure: a biomimetic strategy for advanced polymeric materials. J Am Chem Soc 2004; 126:2058-65. [PMID: 14971940 DOI: 10.1021/ja039127p] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A long lasting challenge in polymer science is to design polymers that combine desired mechanical properties such as tensile strength, fracture toughness, and elasticity into one structure. A novel biomimetic modular polymer design is reported here to address this challenge. Following the molecular mechanism used in nature, modular polymers containing multiple loops were constructed by using precise and strong hydrogen bonding units. Single-molecule force-extension experiments revealed the sequential unfolding of loops as a chain is stretched. The excellent correlation between the single-molecule and the bulk properties successfully demonstrates our biomimetic concept of using modular domain structure to achieve advanced polymer properties.
Collapse
Affiliation(s)
- Zhibin Guan
- Department of Chemistry, 516 Rowland Hall, University of California, Irvine, California 92697-2025, USA.
| | | | | | | | | | | |
Collapse
|
30
|
Brasier M, Green O, Lindsay J, Steele A. Earth's oldest (approximately 3.5 Ga) fossils and the 'Early Eden hypothesis': questioning the evidence. ORIGINS LIFE EVOL B 2004; 34:257-69. [PMID: 14979661 DOI: 10.1023/b:orig.0000009845.62244.d3] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We question the biogenicity of putative bacterial and cyanobacterial 'microfossils' from 3465 Ma Apex cherts of the Warrawoona Group in Western Australia. They are challenged on the basis of integrated multidisciplinary evidence obtained from field and fabric mapping plus new high-resolution research into their context, sedimentology, filament morphology, 'septation' and arrangement. They cannot be distinguished from (and are reinterpreted as) secondary artefacts of amorphous carbon that formed during devitrification of successive generations of carbonaceous hydrothermal dyke vein quartz. Similar structures occur within associated carbonaceous volcanic glass. The null hypothesis of an abiotic or prebiotic origin for such ancient carbonaceous matter is sustained until mutually supporting contextural, morphological and geochemical evidence for a bacterial rather than abiotic origin is forthcoming.
Collapse
Affiliation(s)
- Martin Brasier
- Department of Earth Sciences, Parks Road, Oxford, OX1 3PR, UK.
| | | | | | | |
Collapse
|
31
|
Affiliation(s)
- James B. Beil
- Department of Organic Chemistry, University of Illinois at Urbana Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801
| | - Steven C. Zimmerman
- Department of Organic Chemistry, University of Illinois at Urbana Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801
| |
Collapse
|
32
|
Teraguchi M, Suzuki JI, Kaneko T, Aoki T, Masuda T. Enantioselective Permeation through Membranes of Chiral Helical Polymers Prepared by Depinanylsilylation of Poly(diphenylacetylene) with a High Content of the Pinanylsilyl Group. Macromolecules 2003. [DOI: 10.1021/ma035493h] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Masahiro Teraguchi
- Graduate School of Science and Technology, Niigata University, Ikarashi 2−8050, Niigata 950-2181, Japan, Center for Transdisciplinary Research, Niigata University, Ikarashi 2-8050, Niigata 950-2181, Japan, and Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto 615-8510, Japan
| | - Jun-ichi Suzuki
- Graduate School of Science and Technology, Niigata University, Ikarashi 2−8050, Niigata 950-2181, Japan, Center for Transdisciplinary Research, Niigata University, Ikarashi 2-8050, Niigata 950-2181, Japan, and Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto 615-8510, Japan
| | - Takashi Kaneko
- Graduate School of Science and Technology, Niigata University, Ikarashi 2−8050, Niigata 950-2181, Japan, Center for Transdisciplinary Research, Niigata University, Ikarashi 2-8050, Niigata 950-2181, Japan, and Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto 615-8510, Japan
| | - Toshiki Aoki
- Graduate School of Science and Technology, Niigata University, Ikarashi 2−8050, Niigata 950-2181, Japan, Center for Transdisciplinary Research, Niigata University, Ikarashi 2-8050, Niigata 950-2181, Japan, and Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto 615-8510, Japan
| | - Toshio Masuda
- Graduate School of Science and Technology, Niigata University, Ikarashi 2−8050, Niigata 950-2181, Japan, Center for Transdisciplinary Research, Niigata University, Ikarashi 2-8050, Niigata 950-2181, Japan, and Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto 615-8510, Japan
| |
Collapse
|
33
|
Morgan MT, Carnahan MA, Immoos CE, Ribeiro AA, Finkelstein S, Lee SJ, Grinstaff MW. Dendritic Molecular Capsules for Hydrophobic Compounds. J Am Chem Soc 2003; 125:15485-9. [PMID: 14664594 DOI: 10.1021/ja0347383] [Citation(s) in RCA: 199] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reichardt's dye, a highly solvatochromic dye, was encapsulated within poly (glycerol succinic acid) ([Gn]-PGLSA-OH) dendrimers to investigate the interior environment of these dendritic macromolecules. The absorption maximum for the encapsulated Reichardt's dye in water was indicative of a relatively high dielectric constant present within the dye/dendrimer complex. (1)H NMR of the encapsulated complex showed the presence of aromatic protons from Reichardt's dye along with the aliphatic protons of the dendrimer. Additionally, there were substantial changes in T(1) and T(2) times of the encapsulated dye when compared with the free dye, and (1)H NOESY spectra for the complex showed a significant number of intermolecular NOE cross-peaks. These data reveal the close through-space proximity of the dye to the dendrimer and the restricted motion of the encapsulated dye. To demonstrate the potential use of these macromolecules as drug delivery vehicles, the poorly water-soluble anticancer drug 10-hydroxycamptothecin (10HCPT) was encapsulated within a carboxylated PGLSA dendrimer ([G4]-PGLSA-COONa). Cytotoxicity assays with human breast cancer cells showed a significant reduction of cell viability, demonstrating that 10HCPT retains activity upon encapsulation.
Collapse
Affiliation(s)
- Meredith T Morgan
- Departments of Chemistry and Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | | | | | | | | | | | | |
Collapse
|
34
|
Affiliation(s)
- Jennifer J. Becker
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290
| | - Michel R. Gagné
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290
| |
Collapse
|
35
|
Zimmerman SC, Zharov I, Wendland MS, Rakow NA, Suslick KS. Molecular Imprinting Inside Dendrimers. J Am Chem Soc 2003; 125:13504-18. [PMID: 14583047 DOI: 10.1021/ja0357240] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Synthetic hosts capable of binding porphyrins have been produced by a mixed-covalent-noncovalent imprinting process wherein a single binding site is created within cross-linked dendrimers. Two synthetic hosts were prepared, using as templates 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin and 5,10,15,20-tetrakis(3,5-dihydroxyphenyl)porphyrin. These two templates were esterified with, respectively, fourth- and third-generation Fréchet-type dendrons containing homoallyl end-groups. The resulting tetra- and octadendron macromolecules underwent the ring-closing metathesis reaction using Grubbs' Type I catalyst, RuCl(2)(P(C(6)H(5))(3))(2)(CHCH(2)C(6)H(5)), to give extensive interdendron cross-linking. Hydrolytic removal of the porphyrin cores afforded imprinted hosts whose ability to bind porphyrins with various peripheral substituents was investigated by UV-visible spectrophotometric titrations and size exclusion chromatography. The results indicate a high yield of imprinted sites that show high selectivity for binding of porphyrins capable of making at least four hydrogen bonds, but only a moderate degree of shape selectivity.
Collapse
Affiliation(s)
- Steven C Zimmerman
- Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
| | | | | | | | | |
Collapse
|
36
|
Mertz E, Beil JB, Zimmerman SC. Kinetics and thermodynamics of amine and diamine signaling by a trifluoroacetyl azobenzene reporter group. Org Lett 2003; 5:3127-30. [PMID: 12916998 DOI: 10.1021/ol0351605] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] (Trifluoroacetyl)azobenzene dyes were previously employed as amine reporter groups (chemosensors) in a dendrimer-based monomolecular imprinting system. Kinetic and binding studies with a range of amines and diamines show that the highly selective signaling observed for alkane diamines by these imprinted dendrimers arises from a kinetic effect due to intramolecular general base-catalyzed carbinolamine formation with the dye itself. The relationship between diamine structure and carbinolamine stability and rate of formation is described.
Collapse
Affiliation(s)
- Eric Mertz
- Department of Chemistry, 600 S. Matthews Ave, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | | | | |
Collapse
|
37
|
Caro G, Bourdon B, Birck JL, Moorbath S. 146Sm-142Nd evidence from Isua metamorphosed sediments for early differentiation of the Earth's mantle. Nature 2003; 423:428-32. [PMID: 12761546 DOI: 10.1038/nature01668] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2002] [Accepted: 04/09/2003] [Indexed: 11/08/2022]
Abstract
Application of the 147Sm-143Nd chronometer (half-life of 106 Gyr) suggests that large-scale differentiation of the Earth's mantle may have occurred during the first few hundred million years of its history. However, the signature of mantle depletion found in early Archaean rocks is often obscured by uncertainties resulting from open-system behaviour of the rocks during later high-grade metamorphic events. Hence, although strong hints exist regarding the presence of differentiated silicate reservoirs before 4.0 Gyr ago, both the nature and age of early mantle differentiation processes remain largely speculative. Here we apply short-lived 146Sm-142Nd chronometry (half-life of 103 Myr) to early Archaean rocks using ultraprecise measurement of Nd isotope ratios. The analysed samples are well-preserved metamorphosed sedimentary rocks from the 3.7-3.8-Gyr Isua greenstone belt of West Greenland. Our coupled isotopic calculations, combined with an initial epsilon 143Nd value from ref. 6, constrain the mean age of mantle differentiation to 4,460 +/- 115 Myr. This early Sm/Nd fractionation probably reflects differentiation of the Earth's mantle during the final stage of terrestrial accretion.
Collapse
Affiliation(s)
- Guillaume Caro
- Laboratoire de Géochimie et Cosmochimie (UMR 7579 CNRS), Institut de Physique du Globe de Paris, Université Denis Diderot 4, place Jussieu,75252 Paris Cedex 05, France.
| | | | | | | |
Collapse
|
38
|
Han M, Kane R, Goto M, Belfort G. Discriminate Surface Molecular Recognition Sites on a Microporous Substrate: A New Approach. Macromolecules 2003. [DOI: 10.1021/ma021736e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mina Han
- Howard P. Isermann Department of Chemical Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590, and Department of Chemical Systems and Engineering, Graduate School of Engineering, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
| | - Ravi Kane
- Howard P. Isermann Department of Chemical Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590, and Department of Chemical Systems and Engineering, Graduate School of Engineering, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
| | - Masahiro Goto
- Howard P. Isermann Department of Chemical Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590, and Department of Chemical Systems and Engineering, Graduate School of Engineering, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
| | - Georges Belfort
- Howard P. Isermann Department of Chemical Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590, and Department of Chemical Systems and Engineering, Graduate School of Engineering, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
| |
Collapse
|
39
|
Affiliation(s)
- Michael E. Lipschutz
- Department of Chemistry, Wetherill Laboratory, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907-2038, Department of Chemistry, Indiana State University, Terre Haute, Indiana 47809-5901, and Department of Earth and Environmental Sciences, The George Washington University, 2029 G Street N.W., Washington, D.C. 20006
| | - Stephen F. Wolf
- Department of Chemistry, Wetherill Laboratory, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907-2038, Department of Chemistry, Indiana State University, Terre Haute, Indiana 47809-5901, and Department of Earth and Environmental Sciences, The George Washington University, 2029 G Street N.W., Washington, D.C. 20006
| | - John M. Hanchar
- Department of Chemistry, Wetherill Laboratory, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907-2038, Department of Chemistry, Indiana State University, Terre Haute, Indiana 47809-5901, and Department of Earth and Environmental Sciences, The George Washington University, 2029 G Street N.W., Washington, D.C. 20006
| | - F. Bartow Culp
- Department of Chemistry, Wetherill Laboratory, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907-2038, Department of Chemistry, Indiana State University, Terre Haute, Indiana 47809-5901, and Department of Earth and Environmental Sciences, The George Washington University, 2029 G Street N.W., Washington, D.C. 20006
| |
Collapse
|
40
|
Guo W, Li JJ, Wang YA, Peng X. Luminescent CdSe/CdS core/shell nanocrystals in dendron boxes: superior chemical, photochemical and thermal stability. J Am Chem Soc 2003; 125:3901-9. [PMID: 12656625 DOI: 10.1021/ja028469c] [Citation(s) in RCA: 274] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The surface ligands, generation-3 (G3) dendrons, on each semiconductor nanocrystal were globally cross-linked through ring-closing metathesis (RCM). The global cross-linking of the dendron ligands sealed each nanocrystal in a dendron box, which yielded box-nanocrystals. Although the dendron ligands coated CdSe nanocrystals (CdSe dendron-nanocrystals) were already quite stable, the stability of CdSe box-nanocrystals against chemical, photochemical, and thermal treatments were dramatically improved in comparison to that of the original dendron-nanocrystals. Furthermore, the box structure of the ligands monolayer coupled with the stable inorganic CdSe/CdS core/shell nanocrystals resulted in a class of extremely stable nanocrystal/ligands complexes. The band edge photoluminescence of the core/shell dendron-nanocrystals and box-nanocrystals were partially remained, and could be further brightened through controlled chemical oxidation or photooxidation. Practically, the stability of the box-nanocrystals is sufficient for most fundamental studies and technical applications. The box-nanocrystals may represent a general solution for the commonly encountered instability for many types of colloidal nanocrystals. The size distribution of the empty dendron boxes formed by the dissolution of the inorganic nanocrystals in concentrated HCl was very narrow. The empty boxes as new types of polymer capsules are soluble in solution, mesoporous, and with a very thin but stable peripheral. Those nanometer-sized cavities should be of interest for many purposes in the field of solution host-guest chemistry.
Collapse
Affiliation(s)
- Wenzhuo Guo
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville 72701, USA
| | | | | | | |
Collapse
|
41
|
Mertz E, Zimmerman SC. Cross-linked dendrimer hosts containing reporter groups for amine guests. J Am Chem Soc 2003; 125:3424-5. [PMID: 12643692 DOI: 10.1021/ja0294515] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The integration of a chromogenic reporter group into the recently reported (Zimmerman, S. C.; Wendland, M. S.; Rakow, N. A.; Zharov, I.; Suslick, K. S. Nature 2002, 418, 399-403) monomolecular imprinting approach is described. The resulting highly cross-linked, macromolecular hosts show rapid, selective, high affinity, two-point binding of straight-chain diamine guests. Over longer times, the hosts are more promiscuous, binding a broader range of diamines. A rigorous test of imprinting was performed wherein the cross-reactivities of two dendrimers derived from different templates are compared. The test reveals a guest-dependent kinetic binding effect masquerading as evidence of a highly selective two-point imprinting process.
Collapse
Affiliation(s)
- Eric Mertz
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Matthews Avenue, Urbana, Illinois 61801, USA
| | | |
Collapse
|
42
|
Jones JW, Bryant WS, Bosman AW, Janssen RAJ, Meijer EW, Gibson HW. Crowned dendrimers: pH-responsive pseudorotaxane formation. J Org Chem 2003; 68:2385-9. [PMID: 12636406 DOI: 10.1021/jo0265784] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With the end goal of incorporating the unique structural and physical properties of dendrimers into supramolecular assemblies, bis(m-phenylene)-32-crown-10-functionalized poly(propyleneimine) dendrimers of the first and third generations have been synthesized and their interaction with paraquat diol has been investigated. Using (1)H NMR, we determined that binding to the 4 or 16 crown ether sites occurred in an anti-cooperative fashion, most likely a result of steric influences. Upon protonation of the tertiary amines in the dendritic interior, binding became independent, i.e., statistical, and the average apparent association constant increased by nearly 5-fold; this effect is attributed to rigidification of the dendrimer, which makes its binding sites more accessible and less crowded.
Collapse
Affiliation(s)
- Jason W Jones
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0212, USA
| | | | | | | | | | | |
Collapse
|
43
|
Lowe DR, Byerly GR, Kyte FT, Shukolyukov A, Asaro F, Krull A. Spherule beds 3.47-3.24 billion years old in the Barberton Greenstone Belt, South Africa: a record of large meteorite impacts and their influence on early crustal and biological evolution. ASTROBIOLOGY 2003; 3:7-48. [PMID: 12804363 DOI: 10.1089/153110703321632408] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Four layers, S1-S4, containing sand-sized spherical particles formed as a result of large meteorite impacts, occur in 3.47-3.24 Ga rocks of the Barberton Greenstone Belt, South Africa. Ir levels in S3 and S4 locally equal or exceed chondritic values but in other sections are at or only slightly above background. Most spherules are inferred to have formed by condensation of impact-produced rock vapor clouds, although some may represent ballistically ejected liquid droplets. Extreme Ir abundances and heterogeneity may reflect element fractionation during spherule formation, hydraulic fractionation during deposition, and/or diagenetic and metasomatic processes. Deposition of S1, S2, and S3 was widely influenced by waves and/or currents interpreted to represent impact-generated tsunamis, and S1 and S2 show multiple graded layers indicating the passage of two or more wave trains. These tsunamis may have promoted mixing within a globally stratified ocean, enriching surface waters in nutrients for biological communities. S2 and S3 mark the transition from the 300-million-year-long Onverwacht stage of predominantly basaltic and komatiitic volcanism to the late orogenic stage of greenstone belt evolution, suggesting that regional and possibly global tectonic reorganization resulted from these large impacts. These beds provide the oldest known direct record of terrestrial impacts and an opportunity to explore their influence on early life, crust, ocean, and atmosphere. The apparent presence of impact clusters at 3.26-3.24 Ga and approximately 2.65-2.5 Ga suggests either spikes in impact rates during the Archean or that the entire Archean was characterized by terrestrial impact rates above those currently estimated from the lunar cratering record.
Collapse
Affiliation(s)
- Donald R Lowe
- Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115, USA.
| | | | | | | | | | | |
Collapse
|