bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degradation of Carbon Nanomaterials Using Electrochemical Oxidation on BDD Electrodes
Authors: Reipa Vytas , Petersen Elijah , Hanna Shannon , Elliott John 
Published: February 2020

Toxic potential of carbon nanomaterials (CN) to environmental species and humans is well documented. As carbon nanomaterials are produced in kiloton quantities worldwide, so is the risk of environmental contamination through industrial discharge and use (1). Eventually such discharge may diffuse through aquifers and residential drinking water. Significant challenges exist in decontaminating the effluent water, containing carbon nanomaterials. Carbon nanomaterials can be destroyed or degraded by incineration, however it requires the ability to locate, collect and concentrate carbon nanomaterial sample from the environment, which is often quite complicated. We have investigated the way to rapidly and significantly decrease the CN concentration in aqueous suspensions, thus reducing its toxic potential.
Carbon nanomaterial degradation is based on generating strong oxidizing agents on a boron doped diamond anode, combined with a vigorous solution turbulence due to gas evolution inside a thin layer flow-through cell at high current densities. These agents react with carbon nanomaterials, damage them through multiple oxidations, destroy their structural integrity and rapidly reduce their concentration in aqueous solvents. In addition, the inert cathode surface facilitates hydrogen peroxide production due to the dissolved oxygen reduction reaction. As a result of strong oxidative reactions between nanomaterials and oxidative radicals, the outflowing water has a significantly lower concentration of suspended nanomaterials and, consequently is less toxic to the environment.
The method was tested with pristine single and multiwall carbon nanotube, graphene and fullerene aqueous suspensions. UV-VIS-NIR absorbance show that CN concentration is reduced below 1% in a single pass through the single compartment electrochemical cell, thus offering a much faster way to degrade environmental toxicants compared to enzymatic or Fenton reaction approaches (2). Raman spectroscopy and analysis of the reaction products shows that oxidative attack on CN sp
2
–based structure by electrochemically generated reactive oxygen species leads to nanoparticle integrity loss and subsequent oxidation to CO2 .
References

Petersen, E. J. et al., Environ. Sci. Technol. 2011, 45, 9837-9856.

Allen, B. L. et al., J. Am. Chem. Soc. 2009, 131, 17194-17205.
(Invited) Cavity Enhanced Light Emission from Electrically Driven Carbon Nanotubes
Authors: Krupke Ralph 
Published: February 2020

An important advancement towards optical communication on a chip would be the development of integrable, nanoscale photonic emitters with tailored optical properties. Here we demonstrate the use of carbon nanotubes as electrically driven high-speed emitters in combination with a nanophotonic cavity which allows for exceptionally narrow linewidths [1]. The one-dimensional photonic crystal cavities are shown to spectrally select desired emission wavelengths, enhance intensity and efficiently couple light into the underlying photonic network with high reproducibility. Under pulsed voltage excitation we realize on-chip modulation rates in the GHz range, compatible with active photonic networks. Because the linewidth of the molecular emitter is determined by the quality factor of the photonic crystal, our approach effectively eliminates linewidth broadening due to temperature, surface interaction and hot-carrier injection.
This work was supported by the Volkswagen Foundation, by the Helmholtz Society through the program STN and the KNMF.
[1] Felix Pyatkov, Valentin Fütterling, Svetlana Khasminskaya, Benjamin Flavel, Frank Hennrich, Manfred M. Kappes, Ralph Krupke, and Wolfram H.P. Pernice, under review
Advanced Spectral Analysis for Characterizing Single-Walled Carbon Nanotube Samples
Authors: Weisman R. Bruce , Bachilo Sergei M. , Kadria-Vili Yara 
Published: February 2020

Single-walled carbon nanotubes (SWCNTs) are a family of 1D nanomaterials with the potential for a range for novel applications. However, accurate and convenient characterization is still an important challenge, since most SWCNT samples contain mixtures of many structural forms ((n,m) species) with different electronic, optical, mechanical, and chemical properties. Fluorescence emission, fluorescence excitation, and absorption spectra of such mixed samples are complex superpositions, with each (n,m) species giving multiple peaks. Therefore proper sample analysis requires detailed knowledge of the positions, widths, and intensities of those spectral features. Here we report progress in determining semiconducting SWCNT sample compositions by carefully analyzing the absorption and emission spectra simultaneously.
One step in this approach is determining detailed fluorescence excitation spectra. For this we have prepared samples enriched in a single (n,m) and carefully measured their excitation spectra. Each such spectrum was broken down and modeled as features representing SWCNT electronic and vibronic transitions. We then deduced Voigt or Pearson line shapes that represent positions, widths, and intensities of these peaks as a function of nanotube structure. This has allowed us to construct a model for fluorescence excitation spectra that can be applied to (n,m) species beyond those that were directly measured.
Similarly, to represent (n,m)-dependent emission spectra, we have made careful bulk and single-nanotube studies of features from the singlet bright exciton (E11) and three secondary emissive sidebands. We deduced parameters describing these features as a function of nanotube structure to construct a robust model for SWCNT emission spectra. This model, when combined with the one for excitation, allows the fluorescence spectra of nanotube mixtures to be properly analyzed as a sum of contributions from multiple (n,m) species.
Although this procedure does not reveal absolute species concentrations, the fluorescence analysis can be combined with absorption analysis and recent data for SWCNT absolute absorption cross sections to obtain quantitative sample compositions. For this purpose, the absorption spectrum of a mixed sample is simulated as a background function plus components determined from the fluorescence emission and excitation profiles for the (n,m) species that were found to be present. Then the separate E11 (n,m) absorbance components are divided by their structure-specific absorption cross sections to find absolute species concentrations.
Intensity Ratio of Resonant Raman Modes for (n,m) Enriched Semiconducting Carbon Nanotubes
Authors: Piao Yanmei , Simpson Jeffrey R , Streit Jason K. , Ao Geyou , Zheng Ming , Fagan Jeffrey A. , Hight Walker Angela R. 
Published: February 2020

Relative intensities of resonant Raman spectral features, specifically the radial breathing mode (RBM) and G modes, of eleven, chirality-enriched, single-wall carbon nanotube (SWCNT) species were established under second-order optical transition excitation. The results demonstrate an under-recognized complexity in the evaluation of Raman spectra for the assignment of (n,m) population distributions in agreement with theory predicted by a symmetry-adapted nonorthogonal tight-binding model.[1] Strong chiral angle and mod dependencies affect the intensity ratio of the RBM to G modes. Furthermore, we report five additional values for chirality dependent G+ and G- Raman peak positions and intensity ratios extending the available data to cover more of the smaller diameter regime by including the first (5,4) second-order, resonance Raman spectra.[2] Together, the Raman spectral library is demonstrated to be sufficient for decoupling multiple species viaa spectral fitting process, and enables fundamental characterization even in mixed chiral population samples.
References:
[1] Popov, V. N.; Henrard, L.; Lambin, P. Resonant Raman Intensity of the Radial Breathing Mode of Single-Walled Carbon Nanotubes within a Nonorthogonal Tight-Binding Model. Nano Lett.
2004, 4, 1795–1799.
[2] Telg, H.; Duque, J. G.; Staiger, M.; Tu, X.; Hennrich, F.; Kappes, M. M.; Zheng, M.; Maultzsch, J.; Thomsen, C.; Doorn, S. K. Chiral Index Dependence of the G+ and G– Raman Modes in Semiconducting Carbon Nanotubes. ACS Nano
2012, 6, 904–911.
Alkane Filled Single-Wall Carbon Nanotubes: Endohedral Volume Control for Improved Nanotube Properties
Authors: Campo Jochen , Piao Yanmei , Lam Stephanie , Streit Jason K. , Hight Walker Angela R. , Fagan Jeffrey A. 
Published: February 2020

Liquid-phase processing of single-wall carbon nanotubes (SWCNTs) generally results in the exposure of their core to the environment (opening) due to the energy input necessary for purification and solubilization, and this often affects the SWCNT properties [1-3]. For instance, for aqueous processing, SWCNTs are routinely getting filled with water, which leads to significant redshifts to, and inhomogeneous broadening of, the electronic transitions of the SWCNTs, as well as a substantial decrease of their fluorescence quantum efficiency [1]. Selection of (remaining) empty (end-capped) SWCNTs to avoid these detrimental effects is possible by means of ultracentrifugation, but is a natively low yield process [4]. In this work, adverse filling is prevented by intentionally prefilling the SWCNTs with alkanes, serving as a passive and highly homogeneous spacer. In contrast to water and other encountered fillants, the alkane core is of low dielectric nature and therefore only weakly affects the electronic structure of the SWCNTs, and hence effectively simulates empty core conditions. This yields highly resolved optical spectra with strongly shifted peak positions compared to water filled SWCNTs (see Figure 1), and fluorescence efficiencies approaching those of empty SWCNTs. It is demonstrated that this can be realized using a wide variety of linear as well as cyclic alkanes, in combination with various SWCNT materials having very different diameter distributions.

References

[1] Cambré, S.; Wenseleers, W. Separation and Diameter-Sorting of Empty (End-Capped) and Water-Filled (Open) Carbon Nanotubes by Density Gradient Ultracentrifugation. Angew. Chem. Int. Ed. 2011, 50, 2764–2768.
[2] Cambré, S.; Santos, S. M.; Wenseleers, W.; Nugraha, A. R. T.; Saito, R.; Cognet, L.; Lounis, B. Luminescence Properties of Individual Empty and Water-Filled Single-Walled Carbon Nanotubes. ACS Nano 2012, 6, 2649.
[3] Duque, J. G.; Oudjedi, L.; Crochet, J. J.; Tretiak, S.; Lounis, B.; Doorn, S. K.; Cognet, L. Mechanism of Electrolyte-Induced Brightening in Single-Wall Carbon Nanotubes. J. Am. Chem. Soc. 2013, 135 (9), 3379–3382.
[4] Fagan, J.A; Huh, J.Y.; Simpson, J.R.; Blackburn, J.L.; Holt, J.M.; Larsen, B.A.; Walker, A.R.H. Separation of Empty and Water-Filled Single-Wall Carbon Nanotubes. ACS Nano 2011, 5, 3943–3953.

Figure 1. Optical absorption spectra of electric Arc SWCNTs filled with linear alkanes (C
n
H2n+2) of different lengths, compared to the spectra of water-filled, ethyl acetate-filled (rinsing solvent) and empty Arc SWCNTs. The improved spectral resolution upon alkane encapsulation compared to water filling is clearly visible.

Figure 1
(Invited) New Vistas on Chemistry of Endohedral Metallofullerenes
Authors: Akasaka Takeshi , Yamada Michio , Kurihara Hiroki , Suzuki Mitsuaki , Guo Jing-Dong , Olmstead Marilyn M. , Balch Alan L. , Nagase Shigeru , Maeda Yutaka , Lu Xing 
Published: February 2020

The isolated pentagon rule (IPR) states that stable fullerenes have each of their 12 pentagons surrounded by five hexagons. On the contrary, in 2000, that idea was altered by the discovery of the first non-IPR fullerenes, Sc2@C66 and Sc3N@C68. Themolecular structure of Sc2@C66 was assigned to possess a C2v(4348)-C66 cage that contained two sets of double fused pentagons by using 13C NMR spectroscopy and powder X-ray diffraction data analysis. However, that structure has remained a long-standing controversy, since it is thermodynamically unfavorable. Here, we demonstrate definitively that Sc2@C66 does not have the structure that was long believed to be but a brand new type. 2D-NMR spectroscopic and single-crystal X-ray analysis disclose that Sc2@C66 has a C2v(4059)-C66 cage containing two sets of unsaturated linear triquinanes (ULTs), in which three pentagons abut one another and two scandium ions are located within the folds of each of the ULT units. Our identication of Sc2@C66 as Sc2@C2v(4059)-C66 shows that new motifs in carbon cage geometry continue to be discovered and calls attention to the ULT unit, whose aromaticity and coordination chemistry deserve further study.
(Invited) Regioselective Bis-Prato Addition on TNT-EMF (M3N@Ih
-C80, M = Y, Gd) Controlled By Endohedral Metal Cluster
Authors: Yamakoshi Yoko , Aroua Safwan 
Published: February 2020

Aiming the development of stable and controlled way of the chemical functionalization of fullerenes, there have been many reactions so far reported. The Prato reaction1 (1,3-dipolar cycloaddition reaction) has been used by many groups as one of the efficient chemical conversion methods in the preparation of functional fullerene derivatives. This method usually provides sufficiently stable fullerene derivatives in reasonable synthetic yields. Addressing the preparation of biocompatible fullerene derivatives, we are using this Prato reaction for the controlled functionalization of C60, C70 and TNT-EMF2 (M3N@Ih
-C80 or M3N@C80).
C60 usually produces the mono-Prato adduct selectively on the [6,6]-junction. However, as reported by the groups of Dorn3 and Echegoyen,4 M3N@C80 provides the mono-Prato adduct on both [6,6]- and [5,6]-junctions as a results of [6,6]-to-[5,6] isomerization via a [1,5]-sigmatropic rearrangement. The ratio of the thermodynamic regioisomers ([6,6]-mono and [5,6]-mono) was dependent on the size of metal cluster (M3N) inside C80
5 and was not affected by the exohedral functional groups outside C80 cage. 6

Although the bis-Prato addition of C60 proceeded uncontrolled manner, interestingly, bis-Prato addition of M3N@C80 proceeded in a regioselective manner especially in the presence of larger size of endohedoral metal clusters such as Y3N and Gd3N.7 Thermal treatment of bis-Prato adduct of Y3N@C80 caused random isomerization, but the bis-Prato adduct of Gd3N@C80 stayed rather stable presumably by the effect of larger endohedral metal cluster.
(1) Maggini, M.; Scorrano, G.; Prato, M. J. Am. Chem. Soc. 1993, 115, 9798. (2) Stevenson, S.; Rice, G.; Glass, T.; Harich, K.; Cromer, F.; Jordan, M. R.; Craft, J.; Hadju, E.; Bible, R.; Olmstead, M. M.; Maitra, K.; Fisher, A. J.; Balch, A. L.; Dorn, H. C. Nature
401, 898. (3) Cai, T.; Slebodnick, C.; Xu, S.; Harich, L.; Glass, T. E.; Chancellor, C.l Fettinger, J. C.; Olmstead, M. M.; Balch, A. L.; Gibson, H. W.; Dorn, H. C. J. Am. Chem. Soc. 2006, 128, 6486. (4) Cardona, C. M.; Eliott, B.; Echegoyen, L. J. Am. Chem. Soc. 2006, 128, 6480. (5) Aroua, S.; Yamakoshi, Y. J. Am. Chem. Soc. 2012, 134, 20242. (6) Aroua, S.; Garcia-Borras, M.; Osuna, S.; Yamakoshi, Y. Chem. Eur. J. 2014, 20, 14032. (7) Aroua, S.; Garcia-Borràs, M.; Bölter M. F.; Osuna, S.; Yamakoshi, Y. J. Am. Chem. Soc. 2015, 137, 58.

Figure 1
(Invited) 1,3-Dipolar Cycloadditions on Endohedral Fullerenes M3N@I

h
-C80 (M = Sc-Gd): Remarkable Endohedral-Cluster Regiochemical Control
Authors: Osuna Sílvia , Garcia-Borràs Marc , Yamakoshi Yoko , Echegoyen Luis 
Published: February 2020

Since the C60 discovery in 1985, many fullerene structures have been synthesized and a variety of experimental and computational studies regarding the fullerene stability, characterization, properties such as aromaticity, and reactivity have been reported.1 The huge interest engendered by these fullerene-based materials is mainly attributed to their potential applications in the electronics, photovoltaics, biology, and medicine fields. Obstacles to such bio-applications include their poor solubility in water necessitating the preparation of water-soluble materials by suitable modifications. One of the most useful methods to functionalize fullerenes is via 1,3-dipolar cycloaddition (i.e. Prato reaction). The complete structural, chemical and electronic properties of (metallo)fullerenes are not totally understood at the present time. Specifically, the factors controlling the regiochemistry of multiple additions remain largely unexplored and poorly understood. In this communication, we rationalize using DFT calculations both the effect of the exohedral moiety and the orientation of the encapsulated cluster on the regioselectivity of the Prato (bis)addition to the Ih-C80 based endohedral metallofullerenes, M3N@Ih
-C80 (M=Sc, Lu, Y, and Gd).2-4

1M. Garcia-Borràs, S. Osuna, M. Swart, J. M. Luis, M. Solà, Chem. Soc. Rev., 2014, 43, 5089.

2S. Aroua, M. Garcia-Borràs, S. Osuna, Y. Yamahoshi, Chem. Eur. J. 2014, 20, 14032.

3S. Aroua, M. Garcia-Borràs, M. Bölter, M., S. Osuna, Y. Yamakoshi, J. Am. Chem. Soc. 2015, 137, 58.

4M. R. Cerón, M. Izquierdo, M. Garcia-Borràs, S. S. Lee, S. Osuna, L. Echegoyen, J. Am. Chem. Soc. 2015,
137, 11775.

Figure 1
(Invited) Isolation and Structure Determination of La@C70(CF3)3
Authors: Aoyagi Shinobu , Wang Zhiyong , Omachi Haruka , Kitaura Ryo , Shinohara Hisanori 
Published: February 2020

We report the single-crystal X-ray structure of La@C70(CF3)3, which was obtained through in situ exohedral functionalization by means of trifluoromethylation [1]. The X-ray crystallographic study reveals that La@C70(CF3)3 is the first example of an endohedral rare-earth fullerene based onD
5
h-C70. The dramatically enhanced stability of La@C70(CF3)3 compared to La@C70 can be ascribed to trifluoromethylation-induced bandgap enlargement.
[1] Z. Wang et al., Angew. Chem. Int. Ed. 2015, 54
(Invited) The Regioselectivity of the Diels-Alder and Bingel-Hirsch Additions to La@C2v
-C82
Authors: Solà Miquel , Martínez Juan Pablo , Garcia-Borràs Marc , Swart Marcel , Poater Jordi , Bickelhaupt F. Matthias , Luis Josep Maria , Osuna Sílvia 
Published: February 2020

Two of the most important reactions in fullerene chemistry are the Diels-Alder and the Bingel-Hirsch additions. In this work, we have quantum chemically explored all possible mechanistic pathways of the Diels-Alder cycloaddition of (1,2,3,4,5-pentamethyl)cyclopentadiene and the Bingel-Hirsch addition of dimethyl bromomalonate to La@C2v
-C82 using dispersion-corrected DFT. La@C2v
-C82 has 24 nonequivalent carbon atoms and 35 different bonds (see Figure 1). Our calculations show that the Diels-Alder reaction to La@C2v
-C82 is very regioselective and occurs exclusively on bond o [1]. On the other hand, La@C2v
-C82 is not particularly regioselective under Bingel-Hirsch conditions. Still, from the obtained results one can make a tentative assignment of the products experimentally observed [2]. According to our calculations [3], the observed fulleroid adduct results from the attack to bond 19 and the singly-bonded derivatives correspond to the C2, C19, C21, and C23 initial attacks. However, other possibilities cannot be ruled out completely.

References

1. M. Garcia-Borràs, J. M. Luis, M. Swart, M. Solà, Chem. Eur. J.
2013, 19
, 4468–4479.
2. L. Feng, T. Wakahara, T. Nakahodo, T. Tsuchiya, Q. Piao, Y. Maeda, Y. Lian, T. Akasaka, E. Horn, K. Yoza, T. Kato, N. Mizorogi, S. Nagase, Chem. Eur. J.
2006, 12, 5578–5586.
3. J. P. Martínez, M. Garcia-Borràs, S. Osuna, J. Poater, F. M. Bickelhaupt, M. Solà, submitted for publication.

Figure 1
(Invited) New Endohedral Fullerene Compounds and Derivatives
Authors: Echegoyen Luis 
Published: February 2020

We continue to work with uranium-based endohedral fullerenes and have identified several different families of compounds; some incorporate single uranium atoms encapsulated in different sized carbon cages, others incorporate two uranium atoms in variable sized cages and still other families contain odd numbers of carbons atoms, indicative of possible uranium carbides. Several of these new coompounds are being isolated and characterized and the most recent results will be presented.
We are also working with mixed metallic sulfides, including Dy as one of the encapsulated metals, and have managed to purify some of these. The most recent results at the time of the symposium will be presented and discussed.
Finally, functionalization of endohedral fullerenes continues to be a major component of our research efforts, mainly focused on bis-functionalization, and especially interested in the interplay between endohedral cluster nature and structure and exohedral derivatization. We are also exploring tris-functionalization and will present the most recent results at the symposium.
(Invited) Stabilization of Giant Fullerene Cages By Encapsulation of Large Metallic Clusters
Authors: Lu Xing 
Published: February 2020

Giant tubular fullerenes are prototypes of finite-length end-capped carbon nanotubes (CNTs) which can be accurately characterized by single-crystal X-ray diffraction. We present here the synthesis, isolation and characterization of several novel tubular fullerene cages stabilized by the encapsulation of a large and streched La2C2 cluster, namely, La2C2@C92-C104. The La2C2 cluster no longer has butterfly configuration in large cages such as (450)-C100, Cs(574)-C102 and D3d(822)-C104 , butit adopts a twisted and nearly planar geometry, which is obviously dependent on the cage symmetry. The strong metal-cage interactions are proved to be responsible for the stabilization of these giant fullerene cages. Furthermore, the analysis of the transformation processes from large cages to the smaller ones provides crystallographic evidences for the formation mechanism of ideal CNTs from defective ones at the atomic level as probed with single-crystal crystallography, which is instructive to future works of the selective synthesis of ideal CNTs with identical diameter and chirality.