Carbon Fragments Research Articles

Oxygen isotope analysis of phosphate: improved precision using TC/EA CF‐IRMS

Oxygen isotope values of biogenic apatite have long demonstrated considerable promise for paleothermometry potential because of the abundance of material in the fossil record and greater resistance of apatite to diagenesis compared to carbonate. Unfortunately, this promise has not been fully realized because of relatively poor precision of isotopic measurements, and exceedingly small size of some substrates for analysis. Building on previous work, we demonstrate that it is possible to improve precision of delta18O(PO4) measurements using a 'reverse-plumbed' thermal conversion elemental analyzer (TC/EA) coupled to a continuous flow isotope ratio mass spectrometer (CF-IRMS) via a helium stream [Correction made here after initial online publication]. This modification to the flow of helium through the TC/EA, and careful location of the packing of glassy carbon fragments relative to the hot spot in the reactor, leads to narrower, more symmetrically distributed CO elution peaks with diminished tailing. In addition, we describe our apatite purification chemistry that uses nitric acid and cation exchange resin. Purification chemistry is optimized for processing small samples, minimizing isotopic fractionation of PO4(-3) and permitting Ca, Sr and Nd to be eluted and purified further for the measurement of delta44Ca and 87Sr/86Sr in modern biogenic apatite and 143Nd/144Nd in fossil apatite. Our methodology yields an external precision of +/- 0.15 per thousand (1sigma) for delta18O(PO4). The uncertainty is related to the preparation of the Ag3PO4 salt, conversion to CO gas in a reversed-plumbed TC/EA, analysis of oxygen isotopes using a CF-IRMS, and uncertainty in constructing calibration lines that convert raw delta18O data to the VSMOW scale. Matrix matching of samples and standards for the purpose of calibration to the VSMOW scale was determined to be unnecessary. Our method requires only slightly modified equipment that is widely available. This fact, and the demonstrated improvement in precision, should help to make apatite paleothermometry far more accessible to paleoclimate researchers.

Seasonal features of aerosol particles recorded in snow from Mt. Qomolangma (Everest) and their environmental implications

To assess the seasonality of aerosol deposition and anthropogenic effects on central Himalayas, a 1.85-m deep snow pit was dug on the northern slope of Mt. Qomolangma (Everest). Based on the morphology and energy dispersive X-ray (EDX) signal, totally 1500 particles were classed into 7 groups: soot; aluminosilicates; fly ash; calcium sulfates; Ca/Mg carbonates; metal oxides; and biological particles and carbon fragments. The size distribution and number fractions of different particle groups exhibited distinct seasonal variations between non-monsoon and monsoon periods, which are clearly related to the differences in air mass pathways. Specifically, the relative abundance of soot in non-monsoon period (25%) was much higher than that in monsoon period (14%), indicating Mt. Qomolangma region received more anthropogenic influence in non-monsoon than monsoon period.

Theoretical studies of structure, function and reactivity of molecules--a personal account.

Last few decades theoretical/computational studies of structure, function and reactivity of molecules have been contributing significantly in chemistry by explanation of experimental results, better understanding of underlying principles and prediction of the unknown experimental outcome. Accuracy needed in chemistry has long been established, but due to high power dependency of such accurate methods on the molecular size, it has been a major challenge to apply theoretical methods to large molecular systems. In the present article we will review some examples of such applications. One is theoretical study of growth/formation of carbon nanostructures such as fullerenes and carbon nanotubes, using quantum mechanical molecular dynamics method. For growth of single walled carbon nanotube from transition metal cluster, we have demonstrated continued growth of attached nanotube, cap formation and growth from small carbon fragments. For homogeneous catalysis we presented results of studies on N2 activation by Zr complexes. For biomolecular reactions we use active site and protein models and show that in some catalyses the protein environment is involved in reactions and changes the preferred pathway, and in some other case the effect is modest. The review is concluded with a perspective.

Dissociation of methanol by ion-impact: Breakup dynamics, bond rearrangement and kinetic energy release

The dissociation dynamics of multiply charged methanol molecules formed in collision with 1.2 MeV Ar 8+projectiles is studied. Using coincidence mapping techniques, we can separate out the different dissociation pathways between carbon, oxygen and hydrogen ionic fragments as well as two- and three-body breakup events. Reactions involving intramolecular bond rearrangements within the CH 3 group of the dissociative molecule are discussed in detail. A signature of hydrogen migration in doubly charged methanol is observed. Kinetic energy releases of different breakup channels are reported here and compared with values calculated from a Coulomb explosion model. The shape and orientation of the islands in the coincidence map give further information about the momentum balance in the fragmentation process of two- or many-body dissociation pathways.

Rapid Growth of a Single-Walled Carbon Nanotube on an Iron Cluster: Density-Functional Tight-Binding Molecular Dynamics Simulations

Continued growth of a single-walled carbon nanotube (SWNT) on an Fe cluster at 1500 K is demonstrated using quantum chemical molecular dynamics simulations based on the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. In order to deal with charge transfer between carbon and metal particles and the multitude of electronic states, a finite electronic temperature approach is applied. We present trajectories of 45 ps length, where a continuous supply of carbon atoms is directed toward the C-Fe boundary between a 7.2 A long armchair (5,5) SWNT fragment and an attached Fe(38) cluster. The incident carbon atoms react readily at the C-Fe interface to form C- and C(2)-extensions on the tube rim that attach to the Fe cluster. These bridging sp-hybridized carbon fragments are vibrationally excited and highly mobile and, therefore, become engaged in frequent bond formation and breaking processes between their constituent C and the Fe atoms. The sp-hybridized carbon bridge dynamics and their reactions with the Fe-attached nanotube end bring about formations of new five-, six-, and seven-membered carbon rings extending the tube sidewall, resulting in overall continued growth of the nanotube on the Fe cluster up to nearly twice its length. Due to the random nature of new polygon formation, sidewall growth is observed as an irregular process without clear SWNT chirality preference. Compared to fullerene formation, heptagon formation is considerably promoted.

Carbonization process and SiC formation at C60/Si(111) interface studied by SRPES

Carbonization process and SiC formation upon annealing the Si(111) surface covered by C60 molecules with the thickness of 1.3 nm have been investigated by using synchrotron radiation photoelectron spectroscopy (SRPES), X-ray photoemission (XPS) and reflection high energy electron diffraction (RHEED) in NSRL. C60 molecules are chemisorbed on the Si(111) surface at room temperature, via Si-C60 hybridization to form covalent bonds, which can be explained by adsorption model including two adsorption configurations S3 and L With annealing the sample, the Si-C60 hybridization weakened C-C bonds internally in C60 molecules and enhanced the formation of SixC60, an intermediate species. Further annealing the sample to 650°C will lead to the decomposition of C60 molecules, the released carbon fragment will bond with external silicon atoms to form SiC. While annealing the sample to 850°C, decomposition of all C60 molecules was accomplished, and only a SiC film was left on the surface.

Ion-induced dissociation dynamics of acetylene

We report on the results of dissociation dynamics of multiple charged acetylene molecules formed in collision with 1.2 MeV ${\text{Ar}}^{8+}$ projectiles. Using the coincidence map, we can separate out the different dissociation pathways between carbon and hydrogen ionic fragments as well as complete two-body breakup events. From the measured slopes of the coincidence islands for carbon atomic fragments and theoretical values determined from the charge and momentum distribution of the correlated particles, we observe a diatomlike behavior of the C--C charged complex during dissociation of multiply charged ${\text{C}}_{2}{\text{H}}_{2}$. We conclude that this behavior in breakup dynamics is a signature of sequentiality in dissociation of this multiply charged molecular species. The shape and orientation of the islands give further information about the momentum balance in the fragmentation process of two- or many-body dissociation pathways. Kinetic energy release of different breakup channels are reported here and compared with values calculated from the pure Coulomb explosion model.

Dessorção iônica e degradação de filmes de polipirrol dopado com dodecilsulfato induzidas por elétrons de alta energia

Electron stimulated ion desorption (ESID) and degradation studies of polypyrrole doped with dodecylsulfate (PPy/DS) deposited on FTO were performed using time-of-flight mass spectrometry (TOF-MS) for ion analysis. The results suggest a strong contribution from fragments of the dodecylsulfate hydrocarbon chain to the mass spectra. In the 650-1500 eV energy range the ion yield curves show maxima at about 600, 1200 and 1400 eV, which can be related to carbon, nitrogen and oxygen-containing fragments, respectively, and interpreted in terms of the Auger Stimulated Ion Desorption (ASID) mechanism. Degradation studies indicate rapid loss of heavier hydrocarbons and an increase of bulk and substrate fragments. Some degradation profiles suggest formation of new species.

Theoretical Studies of Chemical Reactions—A Fascinating World of Chemistry from Gas-Phase Elementary Reactions through Nanostructure Formation and Homogeneous Catalysis to Reactions of Metalloenzymes

Abstract Theoretical/computational studies of chemical reactions provide insight into detailed pathways and energy profiles that are not easily available from experiments. Although finding the potential energy profile for ground-state reactions of small molecular systems has become routine, there are many challenges in theoretical studies of chemical reactions. There are still a lot to learn from gas-phase reactions of small molecular systems, starting from an excited state and cascading though many potential surfaces via conical intersections. Molecular dynamics using quantum mechanical energy (QM/MD) was found to be an ideal tool for study of reactions occurring far from equilibrium, such as formation of fullerenes from small carbon fragments and growth of carbon nanotubes. Challenges in theoretical studies of homogeneous catalysis are subtle ligand effects, involvement of multiple spin states and cooperative effects of multiple metal centers. Discussions here cover stories on activation of molecular nitrogen by zirconium complexes, olefin epoxidation by Salen complexes and reactions of tri-ruthenium complexes. Metalloenzymatic reactions have been discussed using protein models with ONIOM QM:MM approaches as well as active site models. Cases are presented where the enzymatic environment makes rather small effects, where it makes energetically significant effects and where it participates positively into the reaction coordinate.

Hyper-parallel tempering Monte Carlo simulations of Ar adsorption in new models ofmicroporous non-graphitizing activated carbon: effect of microporosity

The adsorption of gases on microporous carbons is still poorly understood, partly becausethe structure of these carbons is not well known. Here, a model of microporous carbonsbased on fullerene-like fragments is used as the basis for a theoretical study of Aradsorption on carbon. First, a simulation box was constructed, containing a plausiblearrangement of carbon fragments. Next, using a new Monte Carlo simulation algorithm,two types of carbon fragments were gradually placed into the initial structure to increaseits microporosity. Thirty six different microporous carbon structures were generated in thisway. Using the method proposed recently by Bhattacharya and Gubbins (BG), themicropore size distributions of the obtained carbon models and the average microporediameters were calculated. For ten chosen structures, Ar adsorption isotherms (87 K) weresimulated via the hyper-parallel tempering Monte Carlo simulation method. The isothermsobtained in this way were described by widely applied methods of microporouscarbon characterisation, i.e. Nguyen and Do, Horvath–Kawazoe, high-resolutionαs plots, adsorption potential distributions and the Dubinin–Astakhov (DA) equation. Fromsimulated isotherms described by the DA equation, the average micropore diameters werecalculated using empirical relationships proposed by different authors and they werecompared with those from the BG method.

Dissociation of Methanol and Acetylene by slow Highly Charged Ion Collision

We report here the results of dissociation of multiple charged methanol and acetylene molecules in collision with 1.2 MeV Ar8+ projectiles. We observed a wide range of dissociation products from the TOF spectrum starting from undissociated molecular ions, fragments losing an hydrogen atom due to breakage of C–H and/or O–H bonds, to complete rupture of C–C and C–O skeletons for the respective molecules. From the coincidence map of the fragments, we could separate out the different dissociation channels between carbon and oxygen ionic fragments as well as complete two-body dissociation events. The most striking feature in the breakup of CH3OH is the formation of H2+ and H3+ due to intramolecular rearrangement of the C–H bonds within the methyl group. In dissociative ionization studies of C2H2, we observed a diatom-like behaviour of the C–C charged complex as evidenced from the measured slopes of the coincidence islands for carbon atomic charged fragments and theoretical values determined from the charge and momentum distribution of the correlated particles. The shape and orientation of the islands give further information about the momentum balance in the fragmentation process in two-body dissociation.

Specific Surface Effects on the Storage of Hydrogen on Carbon Nanostructures

We present a study of the adsorption of hydrogen on nanotube bundles and 4 different carbon fragment geometries as a function of their specific surface. The sorption process is investigated using grand canonical Monte Carlo methods in terms of the gravimetric and volumetric storage densities, as a function of radius, lattice spacing and temperature. The carbon fragments are contrived structures designed to study the effect of density and specific surface on physisorption of hydrogen on carbon nanostructures. They have a specific surface ranging from 2700 to 9220 m2/gr (with decreasing bulk density as the specific surface is increased). At low pressure, the gravimetric adsorbed density of hydrogen was observed to increase with the density of the carbon nanostructure. This trend is reversed at high pressure, where the specific surface available for adsorption plays a more important role. For physisorbed hydrogen, these results confirm that maximizing the specific surface of the adsorbent seems to remain the optimal strategy for the design of materials for hydrogen storage if volumetric considerations are not taken into account.

Time-Resolved Synchrotron XPS Monitoring of Irradiation-Induced Nitrobenzene Reduction for Chemical Lithography

The irradiation-induced reduction of electrochemically grafted nitrobenzene films on Si(111) was monitored by high-resolution photoelectron spectroscopy. The experiments were performed using synchrotron soft X-ray irradiation at the BESSY II synchrotron facility. The evolution of different chemical species was monitored as a function of time. Careful fitting of the Si2p, C1s, N1s, and O1s core level spectra allowed us to follow this process in detail and to determine the constants of growth and decay of the specific components. The chemical changes were caused by the X-ray irradiation-induced secondary electron current through the aryl layer. A minor fraction (approximately 25%) of the initial nitro groups was split off and desorbed. The bulk of the NO2 groups was reduced to species in an amino-like chemical environment. A desorption of carbon fragments was not observed, and benzene ring specific shakeup satellites indicated that the aromatic ring structure remained intact. Irradiation-induced line-shape changes suggest a polymerization via -NH- bridges, which were formed after the irradiation-induced N-O bond splitting. A significant part of the released oxygen appeared to contribute to an oxidation of the silicon substrate at the Si(111)/benzene interface. The irradiation-induced aryl layer modification can be exploited for chemical lithography (i.e., a lateral structuring of functionalized silicon surfaces).

Cloning and structural analysis of Mycobacterium leprae serine hydroxymethyltransferase

Serine hydroxymethyltransferase (SHMT) plays a key role in cell physiology as it participates in the different interconversion pathway of folate coenzymes, provides almost exclusively folate one carbon fragments for the biosynthesis of a variety of end products. For the first time, Mycobacterium leprae glyA gene, encodes the enzyme serine hydroxymethyltransferase, has been cloned in Escherichia coli, over-expressed and purified the protein product ( mlSHMT) for folding and stability studies under various denaturating conditions. The recombinant mlSHMT exists as homo-dimer of molecular mass about 90 kDa under physiological conditions . The studies on catalytic properties of mlSHMT show that the enzyme catalyzes the H 4-folate dependent retro-aldol cleavage of l-serine, however, d-alanine dependent transaminase activity was absent in the enzyme. Further analysis of the enzyme kinetics for hydroxymethyltransferase reaction for mlSHMT demonstrates a comparable K m value for l-serine to SHMTs from other sources but significantly lower catalytic efficiency ( k cat /K m). The mlSHMT is resistant to alkaline denaturation and exist as apo-dimer up to pH 10.5. Urea and guanidinium chloride induces dissociation of mlSHMT dimer into monomer at low denaturant concentrations, and leads to loss of enzymatic activity.

Phospholipase Action of Platelet-activating Factor Acetylhydrolase, but Not Paraoxonase-1, on Long Fatty Acyl Chain Phospholipid Hydroperoxides

Phospholipid hydroperoxide (PLOOH) degrading activity of high density lipoprotein (HDL)-derived paraoxonase-1 (PON1) was investigated, using peroxidized 1-palmitoyl-2-oleoyl phosphatidylcholine (PCOOH) as substrate and high performance thin layer chromatography for quantitative peroxide analysis. Incubation of PCOOH with PON1 resulted in decay of the latter and reciprocal buildup of oleic acid hydroperoxide (OAOOH) at rates unaffected by GSH or other reductants. A serine esterase inhibitor blocked this activity and a recombinant PON1 was devoid of it, raising the possibility that the activity represents platelet-activating factor acetylhydrolase (PAF-AH), an esterase that co-purifies with PON1 from HDL. This was verified by showing that a recombinant PAF-AH recapitulates the ability of natural PON1 to hydrolyze PCOOH and release OAOOH while having essentially no effect on parental PC. Furthermore, recombinant PAF-AH and natural PON1 were shown to have similar K(m) values for PCOOH hydrolysis. Finally, we found that recombinant PAF-AH, but not PON1, catalyzes PLOOH hydrolysis in peroxidized low density lipoprotein. We conclude from this study that PON1 is neither a PLOOH peroxidase nor hydrolase and that the phospholipase A(2)-like activity previously attributed to PON1 in natural enzyme preparations was actually due to novel PLOOH hydrolytic activity of contaminating PAF-AH.

Microdosimetric Evaluation of Secondary Particles in a Phantom Produced by Carbon 290 MeV/nucleon Ions at HIMAC

Microdosimetric single event spectra as a function of depth in a phantom for the 290 MeV/nucleon therapeutic carbon beam at HIMAC were measured by using a tissue equivalent proportional counter (TEPC). Two types of geometries were used: one is a fragment particle identification measurement (PID-mode) with time of flight (TOF) method without a backward phantom, and the other is an in-phantom measurement (IPM-mode) with a backward phantom. On the PID-mode geometry, fragments produced by carbon beam in a phantom are identified by the DeltaE-TOF distribution between two scintillation counters positioned up- and down-stream relative to the tissue equivalent proportional counter (TEPC). Lineal energy distributions for carbon and five ion fragments (proton, helium, lithium, beryllium and boron) were obtained in the lineal-energy range of 0.1-1000 keV/microm at eight depths (7.9-147.9 mm) in an acrylic phantom. In the IPM-mode geometry, the total lineal energy distributions measured at eight depths (61.9-322.9 mm) were compared with the distributions in the PID-mode. Both spectra are consistent with each other. This shows that the PID-mode measurement can be discussed as the equivalent of the phantom measurement. The dose distribution of the carbon beam and fragments were obtained separately. In the depth dose curve, the Bragg peak was observed. Relative biological effectiveness (RBE) for the carbon beam in the acrylic phantom was obtained based on a biological response function as a lineal-energy. The RBE of carbon beam had a maximum of 4.5 at the Bragg peak. Downstream of the Bragg peak, the RBE rapidly decreases. The RBE of fragments is dominated by Boron particles around the Bragg peak region.

Changes in the global carbon cycle occurred as two episodes during the Permian–Triassic crisis

Research Article| December 01, 2007 Changes in the global carbon cycle occurred as two episodes during the Permian–Triassic crisis Shucheng Xie; Shucheng Xie 1Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, and State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, People's Republic of China Search for other works by this author on: GSW Google Scholar Richard D. Pancost; Richard D. Pancost 2Bristol Biogeochemistry Center, School of Chemistry, University of Bristol, Cantock's Close BS8 1TS, Bristol, UK Search for other works by this author on: GSW Google Scholar Junhua Huang; Junhua Huang 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, People's Republic of China Search for other works by this author on: GSW Google Scholar Paul B. Wignall; Paul B. Wignall 4School of Earth and Environment, University of Leeds, LS2 9JT, Leeds, UK Search for other works by this author on: GSW Google Scholar Jianxin Yu; Jianxin Yu 5Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, China University of Geosciences, Wuhan 430074, People's Republic of China Search for other works by this author on: GSW Google Scholar Xinyan Tang; Xinyan Tang 5Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, China University of Geosciences, Wuhan 430074, People's Republic of China Search for other works by this author on: GSW Google Scholar Lin Chen; Lin Chen 5Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, China University of Geosciences, Wuhan 430074, People's Republic of China Search for other works by this author on: GSW Google Scholar Xianyu Huang; Xianyu Huang 5Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, China University of Geosciences, Wuhan 430074, People's Republic of China Search for other works by this author on: GSW Google Scholar Xulong Lai Xulong Lai 5Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, China University of Geosciences, Wuhan 430074, People's Republic of China Search for other works by this author on: GSW Google Scholar Geology (2007) 35 (12): 1083–1086. https://doi.org/10.1130/G24224A.1 Article history received: 25 Apr 2007 rev-recd: 24 Jul 2007 accepted: 24 Jul 2007 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Shucheng Xie, Richard D. Pancost, Junhua Huang, Paul B. Wignall, Jianxin Yu, Xinyan Tang, Lin Chen, Xianyu Huang, Xulong Lai; Changes in the global carbon cycle occurred as two episodes during the Permian–Triassic crisis. Geology 2007;; 35 (12): 1083–1086. doi: https://doi.org/10.1130/G24224A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Coeval records of ocean, atmosphere, and terrestrial change are crucial to understanding the pattern and causes of global mass extinction across the Permian-Triassic boundary (PTB). However, relationships among changes in different settings remain largely unclear, primarily due to the challenges associated with the correlation among disparate records. Here we compare marine carbon isotopic records with marine and terrestrial environmental and biotic events recorded in sediments from the Meishan PTB section of south China. Time-scaled carbonate carbon isotopes exhibit two gradual major shifts across the PTB at Meishan, and these are duplicable elsewhere around the Tethys Ocean. The two shifts are associated with two episodes of enhanced terrestrial weathering indicated by an increased abundance of 13C-enriched moretanes relative to hopanes and an elevated abundance of black carbon fragments. Key marine events previously reported for the PTB, including photic zone euxinia, faunal mass extinction, and cyanobacterial expansion, also occur as two episodes, coinciding with both of the progressive shifts to negative δ13C values and enhanced weathering. The temporal sequence of the duplicable events suggests that the biotic crisis was a consequence of prolonged and episodic changes in the marine and continental systems, and argues against an extraterrestrial impact as the main cause. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Grafting Boron Nitride Nanotubes: From Polymers to Amorphous and Graphitic Carbon

In this article, using an atom transfer radical polymerization approach, for the first time polystyrene (PS) and polymethyl methacrylate (PMMA) were grafted covalently on boron nitride nanotubes (BNNTs). Then, a technique was developed to fabricate novel amorphous or graphitic carbon−BNNTs composites with a perfect physical contact between the two phases using the polymer-functionalized BNNTs. BNNTs−carbon-balls composite structures were first successfully fabricated. Other experimental route revealed that a C−BN compound nanotubular nanostructure can be fabricated by using polyvinyl pyrrolidone wrapped BNNTs as an effective precursor, which possess well-defined composition variations and a clear interface between the carbon and BN tubular fragments. The obtained polymer-functionalized BNNTs and carbon−BNNTs composites are useful for the mechanical enhancement of polymeric matrixes and in various electrochemical devices.

Optimization of Solvent Composition for Extraction of Multi‐Polarity Molecules

Marine Natural Products (MNP) are currently extracted from a range of organisms that are complex matrices composed of significant organic and inorganic components. In order to optimize the extraction of the MNP, typically large organic molecules composed of polar and nonpolar structural subcomponents, namely a multi‐component solvent should be utilized. In this paper an algorithm is outlined that provides an optimal solvent mixture based on dipole moment and molecular volume calculations. In this model the MNP is divided up into subcomponents, with carbon fragments ranging in size from one to six carbons. The subcomponent is then matched by dipole moment and molecular volume to a common solvent (i.e., ethanol, methanol, etc.). This algorithm is experimentally demonstrated by increasing the quantity of bryostatin extracted from the bryozoa Bugula neritina and chlorophyll from Common Bermudagrass (Cynodon dactylon).

Curved Carbon Fragment of C60 as a Ligand

Metal (Rh and Ir) complexes with corannulene, the ‘curved carbon fragment’ of C60, have been synthesized. Unlike previously reported Cp*-containing complexes, these have labile cyclo­octenes as other ligands, which enable further chemical transformations while the metal is still bound to corannulene. In addition, the authors proposed a ‘hub-migration’ mechanism for the metals on the corannulene.